Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| coexpression of vitreoscilla hemoglobin reduces the toxic effect of expression of d-amino acid oxidase in e. coli. | expression of the gene (daao) encoding d-amino acid oxidase (daao) in escherichia coli typically results in a marked decrease of cell viability, and it has generally been assumed that the consumption of intracellular d-alanine by daao is responsible for this effect. vitreoscilla hemoglobin (vhb) gene (vgb) was coexpressed with rhodosporidium toruloides d-amino acid oxidase in e. coli bl21(de3) and bl21(de3)plyss, expression hosts differing in the stringency of suppressing basal transcription. no ... | 2004 | 15458318 |
| gene expression profiling of escherichia coli expressing double vitreoscilla haemoglobin. | in a recent investigation, expression of a double vitreoscilla haemoglobin (two fused vhb molecules) in escherichia coli grown in shake flasks resulted in higher final cell density and considerably higher levels of ribosomes and trna. in this study, we have investigated the e. coli transcriptome in cells expressing native vhb, double vhb and control cells lacking vhb by hybridising mrna from the different constructs to high-density oligonucleotide arrays. within the 95% confidence interval, 4 an ... | 2004 | 15464604 |
| metabolic engineering for the production of copolyesters consisting of 3-hydroxybutyrate and 3-hydroxyhexanoate by aeromonas hydrophila. | aeromonas hydrophila 4ak4 was able to synthesize copolyesters consisting of 3-hydroxybutyrate (3hb) and about 15 mol-% 3-hydroxyhexanoate (3hhx) (phbhhx) when grown in long chain fatty acids such as dodecanoate regardless of growth conditions. to regulate the unit fraction in phbhhx, phba and phbb genes encoding beta-ketothiolase and acetoacetyl-coa reductase in ralstonia eutropha, were introduced into a. hydrophila 4ak4. when gluconate was used as cosubstrate of dodecanoate, the recombinant pro ... | 2004 | 15468215 |
| [enhanced ergosterol production by recombinant saccharomyces cerevisiae 1190 harboring vitreoscilla hemoglobin gene (vgb)]. | ergosterol is a principal sterol of fungi. it is a raw material for production of vitamin d2, hydrocortisone, progesterone and brassinolide. synthesis of ergosterol requires molecular oxygen, and low oxygen tensions was reported to dramatically reduce ergosterol concentration. vitreoscilla hemoglobin gene (vgb), a homodimeric hemoglobin gene from gram-negative obligate aerobic bacterium vitreoscilla, enables a higher specific cellular oxygen uptake rate, it also improves the oxygen transportatio ... | 2004 | 15971621 |
| [expression of vitreoscilla hemoglobin and nitrilase in the yeast pichia pastoris]. | the expression of the vgb gene in vivo could improve the fermentation density and then contribute the extracellular secretion of the product of bxn gene. constructed the recombination plasmid ppic9k-vgbbxn and transformed into pichia pastoris gs115. the results of pcr and sds-page indicate that the vgb gene and bxn gene had integrated into the genome of pichia pastoris gs115 and expressed in efficient level. also, the protein activity of their products had been verified respectively. shake flask ... | 2004 | 15973999 |
| expression of vitreoscilla haemoglobin in tobacco cell cultures relieves nitrosative stress in vivo and protects from no in vitro. | targeted expression of vitreoscilla haemoglobin (vhb) has been analysed in nicotiana tabacum plants and suspension cultures under various growth and stress conditions. vhb localization to different cell compartments (cytoplasm, chloroplast and mitochondria) was successful, as judged by signal peptide cleavage. the presence of vhb in subcellular compartments did not result in phenotypical differences between these plant lines. in contrast with previous reports, we were unable to discern any signi ... | 2004 | 17147613 |
| vitreoscilla hemoglobin overexpression increases submergence tolerance in cabbage. | agrobacterium tumefaciens was used to deliver the vhb gene into cabbage (brassica oleracea var. cabitata) cv. xiaguang's parent line, 103. using hypocotyls and cotyledon petioles as explants for infection, we obtained a transformation efficiency of 3-5% based on the number of transgenic shoots produced from the number of explants used for infection. molecular analysis indicated that the vhb gene was stably integrated into the cabbage genome and that the vhb gene was expressed at the rna level. c ... | 2004 | 15747159 |
| [recent advances in the study of vitreoscilla hemoglobin(vhb) and related proteins - cloning, expression and physiological actions in heterologons hosts and in transgenic tobacco plants]. | the first bacterial hemoglobin(vhb) was found in a strictly aerobic bacterium, vitreoscilla strain c1, occurring in marshes low in oxygen, but rich in organic matter. the hemoglobin gene is induced under low oxygen tension and may amount to 20 times as high. the expression of vhb promotes cell growth, protein biosynthesis and primary and secondary metabolism of the host cells, because the increased intracellular oxygen accelerates both the function of respiratory chain and terminal oxidases. the ... | 2003 | 15969050 |
| expression of vitreoscilla haemoglobin in hybrid aspen (populus tremula x tremuloides). | we describe the first ever expression of vitreoscilla haemoglobin (vhb) in an economically important boreal woody plant hybrid aspen (populus tremula x tremuloides). vhb has mainly been expressed in biotechnologically important unicellular organisms of both prokaryotic and eukaryotic origin. vhb expression, in this study, was analysed under different greenhouse cultivation conditions and under elevated uv-b illumination. microscope analyses of leaves grown under optimized conditions revealed sig ... | 2003 | 17163905 |
| expression of vitreoscilla hemoglobin improves growth and levels of extracellular enzyme in yarrowia lipolytica. | enhancement in oxygen uptake by high-cell-density cultivations has been achieved previously by expression of the bacterial hemoglobin gene from vitreoscilla. the vitreoscilla hemoglobin (vhb) gene was expressed in the yeast yarrowia lipolytica to study the effect of expression in this commercially important yeast. the expression of vhb in this yeast was found to enhance growth, contrary to reported observations in wild-type saccharomyces cerevisiae in which there was no significant growth enhanc ... | 2003 | 14595778 |
| fusion protein system designed to provide color to aid in the expression and purification of proteins in escherichia coli. | we have designed and constructed a new fusion expression vector (pkw32), which contains the his-tagged vitreoscilla hemoglobin (vhb) coding gene upstream of the multiple cloning site. the pkw32 vector was designed to express target proteins as vhb fusions, which can be purified in one step by affinity chromatography. due to the color of the heme in vhb, the vhb-fused target proteins have a red color that provides a visual aid for estimating their expression level and solubility. the red color ca ... | 2003 | 14597006 |
| fusion protein of vitreoscilla hemoglobin with d-amino acid oxidase enhances activity and stability of biocatalyst in the bioconversion process of cephalosporin c. | in this study we constructed an artificial flavohemoprotein by fusing vitreoscilla hemoglobin (vhb) with d-amino acid oxidase (dao) of rhodotorula gracilis to determine whether bacterial hemoglobin can be used as an oxygen donor to immobilized flavoenzyme. this chimeric enzyme significantly enhanced dao activity and stability in the bioconversion process of cephalosporin c. in a 200-ml bioreactor, the catalytic efficiency of immobilized vhb-dao against cephalosporin c was 12.5-fold higher than t ... | 2003 | 12632405 |
| menadione knocks out vitreoscilla haemoglobin (vhb): the current evidence for the role of vhb in recombinant escherichia coli. | genetically engineering the heterologous bacterial host with the gene (vgb) encoding vitreoscilla haemoglobin (vhb) has been found to provide typical advantages in growth and production, and it has generally been assumed that vhb is responsible for this effect. here, using matched strains of escherichia coli that bear a recombinant r-amylase gene (mk57) or the r-amylase gene and vgb (mk79), we examined this assumption. menadione, which is known to oxidize haem proteins, was tested over a range o ... | 2003 | 12659636 |
| effects of vitreoscilla hemoglobin on the 2,4-dinitrotoluene (2,4-dnt) dioxygenase activity of burkholderia and on 2,4-dnt degradation in two-phase bioreactors. | expression of vgb, encoding vitreoscilla hemoglobin (vhb), in burkholderia strain yv1 was previously shown to improve cell growth and enhance 2,4-dinitrotoluene (2,4-dnt) degradation compared with control strain dnt, especially under hypoxic conditions. in the work reported here, the ratio of 2,4-dnt degraded to oxygen uptake was approximately 5-fold larger for strain yv1 than for strain dnt. the addition of purified vhb to cytosolic fractions of strain dnt increased 2,4-dnt degradation 1.5-fold ... | 2003 | 12743828 |
| isolation, sequencing, and characterization of the cytochrome bo operon from vitreoscilla. | the entire operon encoding the sodium pumping cytochrome bo from the bacterium vitreoscilla was isolated and sequenced, and this sequence was analyzed by blast and hydropathy plots. there are fairly similar phylogenetic relationships which apply to all five proteins, but overall greater similarity to members of the gamma subdivision than the beta subdivision of the proteobacteria. hydropathy plots of all five cyo proteins show near identity with those of the corresponding e. coli subunits, indic ... | 2003 | 12751331 |
| correlation between bacterial haemoglobin gene (vgb) and aeration: their effect on the growth and alpha-amylase activity in transformed enterobacter aerogenes. | to evaluate the effects of bacterial haemoglobin on bacterial growth and alpha-amylase formation under different aeration conditions. | 2003 | 12752814 |
| improving heterologous gene expression in aspergillus niger by introducing multiple copies of protein-binding sequence containing ccaat to the promoter. | to increase the expression level of heterologous gene in aspergillus niger. | 2003 | 12753242 |
| flavohemoglobin hmp, but not its individual domains, confers protection from respiratory inhibition by nitric oxide in escherichia coli. | escherichia coli possesses a two-domain flavohemoglobin, hmp, implicated in nitric oxide (no) detoxification. to determine the contribution of each domain of hmp toward no detoxification, we genetically engineered the hmp protein and separately expressed the heme (hd) and the flavin (fd) domains in a defined hmp mutant. expression of each domain was confirmed by western blot analysis. co-difference spectra showed that the hd of hmp can bind co, but the co adduct showed a slightly blue-shifted pe ... | 2003 | 12826671 |
| extreme uv-a sensitivity of the filamentous gliding bacterium vitreoscilla stercoraria. | strains of the filamentous gliding bacterium vitreoscilla, lb13 and c1, are shown to be highly sensitive to uv-a (320-400 nm), with an ld50 of less than 20 kj m(-2). vitreoscilla lb13 can be protected from uv-a by including superoxide dismutase and catalase, separately or in combination, during the exposure, indicating an involvement of reactive oxygen species. lb13a, a photo-insensitive strain derived from lb13, is described. | 2003 | 12855170 |
| vitreoscilla hemoglobin promoter is not responsive to nitrosative and oxidative stress in escherichia coli. | the vitreoscilla hemoglobin gene (vhb) is expressed under oxygen-limited conditions via an fnr-dependent mechanism. furthermore, camp-crp has been implicated in its regulation. recently, vhb protein has been reported to protect a heterologous host from nitrosative stress. in this study we analyzed the regulation of the vitreoscilla hemoglobin promoter (pvhb) in escherichia coli under nitrosative and oxidative stress conditions. our results show unambiguously that expression of neither vhb nor ch ... | 2003 | 12855179 |
| direct electrochemical characterization of vitreoscilla sp. hemoglobin entrapped in organic films. | the redox properties of a prokaryotic, vitreoscilla sp. hemoglobin (vhb) in fuzzy organic films are studied with electrochemistry. this vhb exhibits irreversible electrochemical response at bare pyrolytic graphite (pg) electrode surfaces. however, upon being entrapped in organic films, the heterogeneous electron transfer rate of vhb will be sufficiently high to produce a quasi-reversible electrochemical response. the observation of electrocatalysis (reduction of o2) by hemes suggests that the pr ... | 2003 | 12878030 |
| evidence for stable transformation of pseudomonas aeruginosa with a puc-based plasmid. | pseudomonas aeruginosa was transformed with puc8:16, a puc-based plasmid bearing the gene (vgb) encoding vitreoscilla (bacterial) hemoglobin (vhb). transformation was initially indicated by an increase in ampicillin resistance from 1500 to 2500 mg l(-1). presence of the plasmid in p. aeruginosa was confirmed by amplification of a portion of vgb from and detection of vhb in the transformant but not the untransformed host. southern blot analysis further indicated that puc8:16 existed as an autonom ... | 2003 | 12889831 |
| genetic engineering of enterobacter aerogenes with the vitreoscilla hemoglobin gene: cell growth, survival, and antioxidant enzyme status under oxidative stress. | hemoglobins in unicellular organisms, like the one here in the bacterium vitreoscilla, have greater chemical reactivity than their homologues in multicellular organisms. they can catalyze redox reactions and may protect cells against oxidative stress. the ability of vitreoscilla hemoglobin to complement deficiencies of terminal cytochrome oxidases in escherichia coli also suggests that this hemoglobin can receive electrons during respiration. in this study, a recombinant strain of enterobacter a ... | 2003 | 12892849 |
| a solid-phase method for evaluation of gold conjugate used in quantitative detection of antigen by immunogold-labeling electron microscopy. | rapid and sensitive screening for confirming the reactivity of reagents, before proceeding for electron microscopy, is highly desirable. elisa-based methods have been shown to be highly efficient and successful for rapid prescreening and optimization of immunological as well as sample-processing reagents for the sensitive detection and quantitation of antigen by electron microscopy. the drawback of these methods lies in their inability to provide any information regarding the gold conjugate used ... | 2003 | 12969545 |
| expression of the gene coding for bacterial hemoglobin improves beta-galactosidase production in a recombinant pichia pastoris. | genes coding for vitreoscilla hemoglobin (vhb) with peroxisome targeting signal (pts1) tag and beta-galactosidase were co-expressed in pichia pastoris under the alcohol oxidase1 (aox1) promoter. the expression of vhb-pts1 had no positive effect on cell growth but significantly enhanced the whole cell beta-galactosidase activity to 4-fold higher than that of vhb-free cell in yeast extract/peptone/methanol medium under aerobic cultivation. | 2003 | 14514050 |
| bacterial hemoglobins and flavohemoglobins: versatile proteins and their impact on microbiology and biotechnology. | in response to oxygen limitation or oxidative and nitrosative stress, bacteria express three kinds of hemoglobin proteins: truncated hemoglobins (tr hbs), hemoglobins (hbs) and flavohemoglobins (flavo hbs). the two latter groups share a high sequence homology and structural similarity in their globin domain. flavohemoglobin proteins contain an additional reductase domain at their c-terminus and their expression is induced in the presence of reactive nitrogen and oxygen species. flavohemoglobins ... | 2003 | 14550944 |
| microbial globins. | globins are an ancient and diverse superfamily of proteins. the globins of microorganisms were relatively ignored for many decades after their discovery by warburg in the 1930s and rediscovery by keilin in the 1950s. the relatively recent focus on them has been fuelled by recognition of their structural diversity and fine-tuning to fulfill (probably) discrete functions but particularly by the finding that a major role of certain globins is in protection from the stresses caused by exposure to ni ... | 2003 | 14560666 |
| biodegradation of 2-chlorobenzoate by recombinant burkholderia cepacia expressing vitreoscilla hemoglobin under variable levels of oxygen availability. | the influence of bacterial hemoglobin, vhb, on dechlorination and degradation of 2-chlorobenzoate (2-cba) by recombinant burkholderia sp. under variable oxygen availability with an initial dissolved oxygen concentration of 0.27 mm-0.72 mm was investigated in batch and continuous culture. ability to express vhb was provided to recombinant burkholderia by transformation with the vhb gene, vgb, on plasmid psc160. 100% of 0.5 mm cba was degraded in cultures with 85% and 70% of total volume as headsp ... | 2003 | 14571952 |
| enhanced ribosome and trna contents in escherichia coli expressing a truncated vitreoscilla hemoglobin mutant analyzed by flow field-flow fractionation. | the ribosome and trna levels of escherichia coli cells, transformed with a native or mutated vitreoscilla hemoglobin genes (vhb), were investigated using asymmetrical flow field-flow fractionation (affff). mutagenesis of rhb by error-prone pcr was carried out to alter the growth behavior of microaerobically cultivated native vhb-expressing e. coli. a vhb mutant, pvmt1, was identified, which was able to reach a remarkably high final a600 of 15, the value of which being 160% higher than that of a ... | 2003 | 14571972 |
| [cloning and expression of vitreoscilla hemoglobin in streptomyces aureofaciens]. | vitreoscilla hemoglobin gene was cloned in streptomyces aureofaciens through e. coli-streptomyces shuttle plasmids constructed by both pij699-puc19(vhb) and pij702-pbr322(vhb). under low dissolved oxygen conditions, expression of hemoglobin enhanced ctc yield of engineering strain more about 40%-60% that that of control by improving oxygen transmission in cells. hemoglobin expression by promoter of tetracycline resistance gene was more effective for oxygen transmission than that by its native pr ... | 2002 | 12557370 |
| [study on effect of vitreoscilla hemoglobin gene expression on growth and metabolism of streptomyces aureofaciens]. | vitreoscilla hemoglobin gene was expressed in s. aureofaciens through promoter of tetracycline resistance gene. characteristics of s. aureofaciens growth and metabolism were studied in 1 m3 fermenter. in high dissolved oxygen concentrations, expression of hemoglobin gene had little effect on growth and metabolism of s. aureofaciens, and there were no obvious differences between engineering strain and control. the chlortetracycline of engineering strain was 22905 u/ml and of control was 22896 u/m ... | 2002 | 12557546 |
| chimeric vitreoscilla hemoglobin (vhb) carrying a flavoreductase domain relieves nitrosative stress in escherichia coli: new insight into the functional role of vhb. | dimeric hemoglobin (vhb) from the bacterium vitreoscilla sp. strain c1 displays 30 to 53% sequence identity with the heme-binding domain of flavohemoglobins (flavohbs) and exhibits the presence of potential sites for the interaction with its fad/nadh reductase partner. the intersubunit contact region of vhb indicates a small interface between two monomers of the homodimer, suggesting that the vhb dimers may dissociate easily. gel filtration chromatography of vhb exhibited a 25 to 30% monomeric p ... | 2002 | 11772621 |
| improved cell growth in tobacco suspension cultures expressing vitreoscilla hemoglobin. | expression of the gene encoding bacterial hemoglobin (vhb) from vitreoscilla has been previously used to improve recombinant cell growth and enhance product formation under microaerobic conditions, a common phenomenon in large-scale cultivations of bacteria. this technology has now been applied to tobacco suspension cultures. tobacco suspension cultures have been generated from vhb-expressing tobacco plants. cell cultures were capable of producing an active hemoglobin. when grown in shake flasks ... | 2002 | 11934289 |
| the x-ray structure of ferric escherichia coli flavohemoglobin reveals an unexpected geometry of the distal heme pocket. | the x-ray structure of ferric unliganded lipid-free escherichia coli flavohemoglobin has been solved to a resolution of 2.2 a and refined to an r-factor of 19%. the overall fold is similar to that of ferrous lipid-bound alcaligenes eutrophus flavohemoglobin with the notable exception of the e helix positioning within the globin domain and a rotation of the nad binding module with respect to the fad-binding domain accompanied by a substantial rearrangement of the c-terminal region. an inspection ... | 2002 | 11964402 |
| optimization of immunogold labeling tem: an elisa-based method for evaluation of blocking agents for quantitative detection of antigen. | we developed an elisa-based method for rapid selection of optimal blocking agents to be used in antigen quantification by immunogold labeling electron microscopy. casein, skim milk, bsa from two sources, acetylated bsa, fish skin gelatin, horse serum, and goat serum were tested for their ability to block nonspecific binding of antibody to recombinant vitreoscilla hemoglobin (vhb) antigen expressed in escherichia coli cells by elisa and the results were confirmed by quantitative immunogold labeli ... | 2002 | 12019302 |
| expression of double vitreoscilla hemoglobin enhances growth and alters ribosome and trna levels in escherichia coli. | in several organisms, expression of a gene encoding dimeric hemoglobin (vhb) from the obligate aerobic bacterium vitreoscilla stercoraria has been shown to increase microaerobic cell growth and enhance oxygen-dependent cell metabolism. in an attempt to further improve these effects of vhb, a gene encoding two vhb genes connected by a short linker of six base pairs was constructed and expressed in escherichia coli(double vhb). escherichia coli cells expressing double vhb reached a cell density 19 ... | 2002 | 12052087 |
| vitreoscilla hemoglobin binds to subunit i of cytochrome bo ubiquinol oxidases. | the bacterium, vitreoscilla, can induce the synthesis of a homodimeric hemoglobin under hypoxic conditions. expression of vhb in heterologous bacteria often enhances growth and increases yields of recombinant proteins and production of antibiotics, especially under oxygen-limiting conditions. there is evidence that vhb interacts with bacterial respiratory membranes and cytochrome bo proteoliposomes. we have examined whether there are binding sites for vhb on the cytochrome, using the yeast two-h ... | 2002 | 12080058 |
| rhizobium etli mutant modulates carbon and nitrogen metabolism in phaseolus vulgaris nodules. | the aim of this study was to evaluate the biochemical events in root nodules which lead to increased yield when bean is inoculated with a rhizobium etli mutant (cfn037) having increased respiratory capacity. cfn037-inoculated plants had 22% more nitrogen (n) than did wild-type (ce3)-inoculated plants. root nodule enzymes involved in nodule carbon and nitrogen assimilation as well as in ureides and amides synthesis were assessed in plants inoculated with cfn037 and the ce3. our results show that ... | 2002 | 12118889 |
| purification, crystallization and preliminary x-ray analysis of the soluble domain of the na+-pumping cytochrome bo quinol oxidase from vitreoscilla. | the 24 kda cyoa soluble domain of vitreoscilla cytochrome bo quinol oxidase, which pumps out na(+) during respiration, has been crystallized from a solution of 2 m ammonium sulfate and 5% 2-propanol. the crystal belongs to cubic space group p4(3)32, with unit-cell parameters a = b = c = 122.2 a, alpha = beta = gamma = 90 degrees and one subunit in the asymmetric unit. a 99.8% complete data set to 3.3 a has been collected at the 17-id beamline of the advanced photon source. the structure was dete ... | 2002 | 12136145 |
| comparison of green fluorescent protein expression in two industrial escherichia coli strains, bl21 and w3110, under co-expression of bacterial hemoglobin. | vitreoscilla hemoglobin (vhb) has been successfully used to enhance production of foreign proteins in several microorganisms including escherichia coli. we compared the expression of an oxygen-dependent foreign protein, green fluorescent protein (gfp) under co-expression of vhb in two typical industrial e. coli strains, bl21 (a b derivative) and w3110 (a k12 derivative), which have different metabolic properties. we employed the nar oxygen-dependent promoter for self-tuning regulation of vhb exp ... | 2002 | 12172620 |
| nitric oxide scavenging and detoxification by the mycobacterium tuberculosis haemoglobin, hbn in escherichia coli. | nitric oxide (no), generated in large amounts within the macrophages, controls and restricts the growth of internalized human pathogen, mycobacterium tuberculosis h37rv. the molecular mechanism by which tubercle bacilli survive within macrophages is currently of intense interest. in this work, we have demonstrated that dimeric haemoglobin, hbn, from m. tuberculosis exhibits distinct nitric oxide dioxygenase (nod) activity and protects growth and cellular respiration of heterologous hosts, escher ... | 2002 | 12207698 |
| intracellular expression of vitreoscilla hemoglobin modifies microaerobic escherichia coli metabolism through elevated concentration and specific activity of cytochrome o. | the function of the reversible oxygen-binding hemoprotein from vitreoscilla (vhb), which enhances oxygen-limited cell growth and recombinant protein production when functionally expressed in escherichia coli, was investigated in wild-type e. coli and in e. coli mutants lacking one of the two terminal oxidases, cytochrome o complex (aerobic terminal oxidase, cyo) or cytochrome d complex (microaerobic terminal oxidase, cyd). deconvolution of vhb, cytochrome o, and cytochrome d bands from in vivo a ... | 2002 | 12209827 |
| inverse metabolic engineering: a strategy for directed genetic engineering of useful phenotypes. | the classical method of metabolic engineering, identifying a rate-determining step in a pathway and alleviating the bottleneck by enzyme overexpression, has motivated much research but has enjoyed only limited practical success. intervention of other limiting steps, of counter-balancing regulation, and of unknown coupled pathways often confounds this direct approach. here the concept of inverse metabolic engineering is codified and its application is illustrated with several examples. inverse me ... | 2002 | 12209828 |
| bacterial hemoglobins and flavohemoglobins for alleviation of nitrosative stress in escherichia coli. | escherichia coli mg1655 cells expressing novel bacterial hemoglobin and flavohemoglobin genes from a medium-copy-number plasmid were grown in shake flask cultures under nitrosative and oxidative stress. e. coli cells expressing these proteins display enhanced resistance against the no(.) releaser sodium nitroprusside (snp) relative to that of the control strain bearing the parental plasmid. expression of bacterial hemoglobins originating from campylobacter jejuni (chb) and vitreoscilla sp. (vhb) ... | 2002 | 12324328 |
| effect of vitreoscilla hemoglobin biosynthesis in escherichia coli on production of poly(beta-hydroxybutyrate) and fermentative parameters. | in order to attain high cell density and low cost production of poly(beta-hydroxybutyrate) (phb), the vitreoscilla globin gene (vgb) was introduced into a novel recombinant strain, escherichia coli vg1 (ptu14). experiments showed that the expression of vgb was under the regulation of dissolved oxygen (do) in broth and the introduction of vgb in vg1 (ptu14) induced the parent promotion effect on cell growth and phb accumulation, especially under low do conditions. further experiments indicated th ... | 2002 | 12351235 |
| pre-screening for antigen detectability in cells: a tem-based solid phase digital immunogold detection method utilizing ultra low volumes of reagents. | rapid and sensitive pre-screening for the presence of antigens in cell samples and confirmation of reactivity of antibodies, before proceeding with electron microscopy, is highly desirable. most of the methods developed for this purpose are generally not very efficient and suitable for dealing with very small volumes of sample and reagents. in this work we present a simple, sensitive and rapid solid phase transmission electron microscope (tem) based method for the detection of picogram (pg) leve ... | 2002 | 12423260 |
| [hemoglobin, from microorganisms to man: a single structural motif, multiple functions]. | haemoglobins from unicellular organisms, plants or animals, share a common structure, which results from the folding, around the heme group, of a polypeptide chain made from 6-8 helices. nowadays, deciphering the genome of several species allows one to draw the evolutionary tree of this protein going back to 1800 millions of years, at a time when oxygen began to accumulate in the atmosphere. this permits to follow the evolution of the ancestral gene and of its product. it is likely that, only in ... | 2002 | 12520866 |
| construction of a novel engineering strain e.coli g830,which is adoptable to high-cell-density fermentation. | a novel engineered strain g830 adoptable to high-cell-density fermentation by integrating bacterial hemoglobin vhb (vitreoscilla hemoglobin gene) into thr operon in the chromosome of pa1 blocking pta-ack metabolic pathway through the homologous recombination between the homologous fragments of integrated plasmid and that of chromosome. the engineered strain g830 was characterized by phenotype observation, pcr, thr mutant, acetate acid detection, western blotting and vhb activity assays. in high ... | 2001 | 12050789 |
| dissection of central carbon metabolism of hemoglobin-expressing escherichia coli by 13c nuclear magnetic resonance flux distribution analysis in microaerobic bioprocesses. | escherichia coli mg1655 cells expressing vitreoscilla hemoglobin (vhb), alcaligenes eutrophus flavohemoprotein (fhp), the n-terminal hemoglobin domain of fhp (fhpg), and a fusion protein which comprises vhb and the a. eutrophus c-terminal reductase domain (vhb-red) were grown in a microaerobic bioreactor to study the effects of low oxygen concentrations on the central carbon metabolism, using fractional (13)c-labeling of the proteinogenic amino acids and two-dimensional [(13)c, (1)h]-correlation ... | 2001 | 11157231 |
| cell growth and oxygen uptake of escherichia coli and pseudomonas aeruginosa are differently effected by the genetically engineered vitreoscilla hemoglobin gene. | vitreoscilla hemoglobin is a good oxygen trapping agent and its presence in genetically engineered escherichia coli helps this bacterium to grow better. here, the potential use of this hemoglobin, for improving the growth and the oxygen transfer properties of pseudomonas aeruginosa as well as escherichia coli, was investigated. to stably maintain it in both bacteria, a broad-host range cosmid vector (phg1), containing the entire coding sequence for vitreoscilla hemoglobin gene and its native pro ... | 2001 | 11164963 |
| optimization of immunogold labeling tem. an elisa-based method for rapid and convenient simulation of processing conditions for quantitative detection of antigen. | we developed an elisa-based method for rapid optimization of various tissue processing parameters in immunogold labeling for electron microscopy. the effects of aldehyde fixation, tannic acid, postfixation, dehydration, temperature, and antigen retrieval on antibody binding activity of vitreoscilla hemoglobin (vhb) expressed in e. coli cells were assayed by elisa and the results confirmed by quantitative immunogold labeling transmission electron microscopy (tem). our results demonstrated that lo ... | 2001 | 11181739 |
| effects of culture conditions on enhancement of 2,4-dinitrotoluene degradation by burkholderia engineered with the vitreoscilla hemoglobin gene. | growth and degradation of 2,4-dinitrotoluene (2,4-dnt) were compared in liquid cultures in shake flasks for burkholderia sp. strain dnt and strain dnt engineered to produce vitreoscilla (bacterial) hemoglobin (strain yv1). parameters varied included aeration rate, initial 2,4-dnt concentration (50 and 200 ppm), and concentration and type of cosubstrate (yeast extract, succinate, casamino acids, and tryptic soy broth). 2,4-dnt degradation increased with increasing cosubstrate concentration and wa ... | 2001 | 11312715 |
| vitreoscilla hemoglobin. intracellular localization and binding to membranes. | the obligate aerobic bacterium, vitreoscilla, synthesizes elevated quantities of a homodimeric hemoglobin (vhb) under hypoxic growth conditions. expression of vhb in heterologous hosts often enhances growth and product formation. a role in facilitating oxygen transfer to the respiratory membranes is one explanation of its cellular function. immunogold labeling of vhb in both vitreoscilla and recombinant escherichia coli bearing the vhb gene clearly indicated that vhb has a cytoplasmic (not perip ... | 2001 | 11331274 |
| [the effects of vitreoscilla hemoglobin expression on growth and antibiotic production in streptomyces cinnamonensis]. | streptomyces cinnamonensis a-10 is a monensin \ producing strain. phz1252 is an e. coli-streptomyces shuttle vector for expressing vhb, in which vhb structural gene is controlled by thiostrepton-inducible promoter ptipa. phz1252 was unstable in s. cinnamonensis, occurring deletion recombination. the deletion dna fragment of phz1252 included not only part of e. coli plasmid but also vhb gene. however, plasmid phz1252 isolated from s. avermitilis transformants, which lost part of e. coli plasmid b ... | 2001 | 11336066 |
| characterization of an inducible oxidative stress response in vitreoscilla c1. | vitreoscilla becomes resistant to killing by hydrogen peroxide and heat shock when pretreated with nonlethal levels of hydrogen peroxide. the pretreated vitreoscilla cells (60 microm hydrogen peroxide for 120 min) significantly increased survival of the lethal dose of 20 mm hydrogen peroxide or heat shock (22 degrees c --> 37 degrees c). this indicates the existence of an adaptive response to oxidative stress. however, cells pretreated with 60 microm hydrogen peroxide became nonresistant to a le ... | 2001 | 11355702 |
| [effect of the gene for bacterial hemoglobin vhb on the effectiveness of the process of escherichia coli-streptomyces interspecies conjugation and production of antibiotics in streptomycetes]. | the bacterial hemoglobin vhb gene was cloned from sliding bacterium vitreoscilla sp. as an element of the system ensuring survival of this microorganism in an environment that contains insufficient amount of oxygen. the vhb gene was transferred from escherichia coli to some streptomyces strains, producers of antibiotics, by the method of intergeneric conjugation using conjugative-integrative plasmid vectors pih1 and pch2. the stability of plasmid dna inheritance was analyzed in the genomes of ex ... | 2001 | 11357376 |
| monomer-dimer equilibrium and oxygen binding properties of ferrous vitreoscilla hemoglobin. | the monomer-dimer equilibrium and the oxygen binding properties of ferrous recombinant vitreoscilla hemoglobin (vitreoscilla hb) have been investigated. sedimentation equilibrium data indicate that the ferrous deoxygenated and carbonylated derivatives display low values of equilibrium dimerization constants, 6 x 10(2) and 1 x 10(2) m(-1), respectively, at ph 7.0 and 10 degrees c. the behavior of the oxygenated species, as measured in sedimentation velocity experiments, is superimposable to that ... | 2001 | 11478898 |
| novel hemoglobins to enhance microaerobic growth and substrate utilization in escherichia coli. | limited oxygen availability is a prevalent problem in microbial biotechnology. recombinant escherichia coli expressing the hemoglobin from vitreoscilla (vhb) or the flavohemoglobin from ralstonia eutropha (formerly alcaligenes eutrophus) (fhp) demonstrate significantly increased cell growth and productivity under microaerobic conditions. we identify novel bacterial hemoglobin-like proteins and examine if these novel bacterial hemoglobins can elicit positive effects similar to vhb and fhp and if ... | 2001 | 11587567 |
| chromosomal integration of the vitreoscilla hemoglobin gene in burkholderia and pseudomonas for the purpose of producing stable engineered strains with enhanced bioremediating ability. | using the put-minitn5 vector system developed by the laboratory of k.n. timmis, the vitreoscilla hemoglobin gene (vgb) was integrated into the chromosomes of pseudomonas aeruginosa and burkholderia cepacia; vitreoscilla hemoglobin (vhb) was expressed at 8.8 and 0.8 nmol/g wet weight of cells in the respective engineered strains. the vgb-bearing p. aeruginosa outgrew wild-type p. aeruginosa and degraded benzoic acid faster than the latter strain at both normal and low aeration. in contrast, the v ... | 2001 | 11598807 |
| [cloning and expression of vhb gene in d-arabitol producing yeast]. | recombinant plasmid pvgb-ex2 containing vitreoscilla hemoglobin gene vgb and formaldehyde resistant gene sfa1 was constructed and transformed into d-arabitol producing yeast strain saccharomyces sp. x-62. the fact that the amount of vhb in transformant cells was considerably higher than that in control cells indicated that gene vgb was expressed in transformant cells. d-arabitol productivity and yield of fermentation by transformants were improved. the most improvement of d-arabitol productivity ... | 2001 | 12549085 |
| [introduction of vitreoscilla hemoglobin gene in a recombinant e. coli for phb production]. | vitreoscilla hemoglobin gene (vgb) was introduced into the recombinant escherichia coli vg1(ptu14) for production of poly-beta-hydroxybutyrate (phb), in order to enhance the oxygen uptake of strain from molecular level and to solve the problem of oxygen limitation in process of fermentation. the carbon monoxide difference spectra analysis of vitreoscilla hemoglobin (vhb) showed that vgb could be successfully expressed in vg1 (ptu14), and this expression was under the regulation of dissolved oxyg ... | 2001 | 12552801 |
| expression of alcaligenes eutrophus flavohemoprotein and engineered vitreoscilla hemoglobin-reductase fusion protein for improved hypoxic growth of escherichia coli. | expression of the vhb gene encoding hemoglobin from vitreoscilla sp. (vhb) in several organisms has been shown to improve microaerobic cell growth and enhance oxygen-dependent product formation. the amino-terminal hemoglobin domain of the flavohemoprotein (fhp) of the gram-negative hydrogen-oxidizing bacterium alcaligenes eutrophus has 51% sequence homology with vhb. however, like other flavohemoglobins and unlike vhb, fhp possesses a second (carboxy-terminal) domain with nad(p)h and flavin aden ... | 2000 | 10618209 |
| cloning and expression of vitreoscilla hemoglobin gene in burkholderia sp. strain dnt for enhancement of 2,4-dinitrotoluene degradation. | the gene (vgb) encoding the hemoglobin (vhb) of vitreoscilla sp. was cloned into a broad host range vector and stably transformed into burkholderia (formerly pseudomonas) sp. strain dnt, which is able to degrade and metabolize 2,4-dinitrotoluene (dnt). vgb was stably maintained and expressed in functional form in this recombinant strain (yv1). when growth of yv1, in both tryptic soy broth and minimal salts broth containing dnt and yeast extract, was compared with that of the untransformed strain ... | 2000 | 10662485 |
| study of cytochrome bo function in vitreoscilla using a cyo(-) knockout mutant. | the bacterium, vitreoscilla, produces a delta mu(na+) across its membrane during respiration. a key enzyme for this function is the cytochrome bo terminal oxidase which, when incorporated into synthetic proteoliposomes, pumps na(+) across the membrane upon the addition of a substrate. a vitreoscilla cytochrome bo knock out (cyo(-)) mutant was isolated by transposon mutagenesis using put-mini-tn5cm. the membranes of this mutant lacked the characteristic 416 nm peak and 432 nm trough in co differe ... | 2000 | 10876157 |
| [expression and roles of hemoglobin gene in bacillus subtilis]. | hemoglobin of the gram-negative bacterium vitreoscilla can bind oxygen strongly and reduce the oxygen requirement of the bacterium. a recombinant plasmid pav was constructed by inserting the hemoglobin gene (vgb) to the downstream of the promoter of beta-lactase gene of the b. subtilis plasmid pak4. the plasmid pav was transferred into strain db104, g331 (a subtilisin-producing b. subtilis) and b53 (a xylanase-producing b. subtilis). the subclones and transfer of the vgb gene into pak4 were dete ... | 2000 | 10887688 |
| error-prone pcr of vitreoscilla hemoglobin (vhb) to support the growth of microaerobic escherichia coli. | expression of the gene encoding bacterial hemoglobin (vhb) from vitreoscilla has been previously used to improve recombinant cell growth and enhance product formation under microaerobic conditions. it is very likely that the properties of vhb are not optimized for foreign hosts; therefore, we used error-prone pcr to generate a number of randomly mutated vhb genes to be expressed and studied in escherichia coli. in addition, the mutated vhb proteins also contained an extension of eight residues ( ... | 2000 | 11005927 |
| nitrite inhibition of vitreoscilla hemoglobin (vhb) in recombinant e. coli: direct evidence that vhb enhances recombinant protein production. | bacteria engineered with the gene (vgb) encoding vitreoscilla hemoglobin (vhb) typically produce more protein than unengineered cells, and it has generally been assumed that vhb is responsible for this effect. here, using matched strains of e. coli that bear a recombinant alpha-amylase gene (mk57) or the alpha-amylase gene and vgb (mk79), we provide evidence supporting this assumption. sodium nitrite (which is known to inhibit heme proteins) was tested over a range of concentrations regarding ef ... | 2000 | 11101316 |
| [expression of vitreoscilla hemoglobin gene in streptomyces avermitilis]. | two expression vectors, pwy101 and pwy102, were constructed by cloning vitreoscilla hemoglobin gene(vhb) with its native oxygen-regulated promoter into e. coli-streptomyces shuttle vector pij653. they were introduced into streptomyces avermitilis, but western blotting experiment failed to detect vhb gene expression. phz1252 is another shuttle vector for expressing vhb, in which vhb structural gene is controlled by a strong, thiostrepton-inducible streptomyces promoter ptipa. phz1252 was transfor ... | 2000 | 12548878 |
| [study on production of poly-beta-hydroxybutyrate by recombinant strain vg1(ptu14)]. | cloning and expression of vitreoscilla hemoglobin gene (vgb) and lambda phage lytic genes (s-rrz) in production of poly-beta-hydroxybutyrate(phb) was studied in different escherichia coli hosts such as e. colijm105, e. colijm109 and vg1. in the recombinant strains, vg1(ptu14) was a superior one which simultaneously contained three exogenes including vgb, s-rrz and phb biosynthesis genes(phbcab). the experimental results showed that after 82 hours fed-batch cult ure in lbg medium in shaking flask ... | 2000 | 12548993 |
| construction and selection of the novel recombinant escherichia coli strain for poly(beta-hydroxybutyrate) production. | heterogeneous cloning of vitreoscilla hemoglobin gene (vgb), lytic genes of phage lambda with s amber mutation (s(-)rrz) and phb biosynthetic genes (phbcab) in the same host strain e. coli jm105 was carried out for production of poly(beta-hydroxybutyrate) (phb). a superior novel strain, vg1 (ptu14), was constructed and selected, which contained the vgb gene in the chromosomal dna and the plasmid ptu14 containing s(-)rrz and phbcab genes. when cultured in 100 ml of lbg medium in a 300-ml flask, a ... | 2000 | 16232750 |
| proton nmr investigation of heme and surrounding proton in low-spin cyanide-ligated bacterial hemoglobin from vitreoscilla. | (1)h nmr spectra of low-spin cyanide-ligated bacterial hemoglobin from vitreoscilla (vthb-cn) are reported. the assignments of the(1)h nmr spectra of vthb-cn have been made through mcosy, noesy, 1d toe and superweft experiments. almost all resonance peaks of heme and ligated his85 are identified. the spin-lattice relaxation time t (1)'s and the variation relationships of chemical shifts of these peaks with temperature have been acquired, from which the distances between the measured protons and ... | 2000 | 18763116 |
| expression of vitreoscilla hemoglobin in escherichia coli enhances ribosome and trna levels: a flow field-flow fractionation study. | asymmetrical flow field-flow fractionation (fff) was used to separate and quantitate 70s ribosomes, the 30s and 50s subunits, and trna in one single analytical procedure. the method was applied to an investigation of the effect of vitreoscilla hemoglobin (vhb) on the translational machinery of the recombinant escherichia coli cells. the number of active 70s ribosomes per cell increased dramatically, more than 2-fold, as did also the trna levels for the vhb-expressing strain relative to vhb-negat ... | 1999 | 10194389 |
| production of alpha-amylase in fed-batch cultures of vgb+ and vgb- recombinant escherichia coli: some observations. | synthesis and excretion of bacillus stearothermophilus alpha-amylase is analyzed in fed-batch cultivations of escherichia coli jm103[pmk79] and e. coli jm103[pmk57], the former strain containing the plasmid-encoded vitreoscilla hemoglobin (vhb) gene (vgb) and the latter strain being devoid of this gene. fed-batch operation is observed to be substantially superior to batch operation as concerns the alpha-amylase production rate and the extent of excretion of the enzyme. faster feeding of a nutrie ... | 1999 | 10441355 |
| anticooperative ligand binding properties of recombinant ferric vitreoscilla homodimeric hemoglobin: a thermodynamic, kinetic and x-ray crystallographic study. | thermodynamics and kinetics for cyanide, azide, thiocyanate and imidazole binding to recombinant ferric vitreoscilla sp. homodimeric hemoglobin (vitreoscilla hb) have been determined at ph 6.4 and 7.0, and 20.0 degrees c, in solution and in the crystalline state. moreover, the three-dimensional structures of the diligated thiocyanate and imidazole derivatives of recombinant ferric vitreoscilla hb have been determined by x-ray crystallography at 1.8 a (rfactor=19.9%) and 2.1 a (rfactor=23.8%) res ... | 1999 | 10448042 |
| a new system for expressing heterologous gene in escherichia coli regulated by oxygen consistence in the environment. | the expression of vitreosilla hemoglobin gene (vgb) is regulated by oxygen consistence in e. coli. the gene transcription is activated under the condition of limited oxygen. a new system for expressing heterologous gene in e. coli regulated by dissolved oxygen consistence was constructed. it includes a host bacteria gj100, which contained t7 rna polymerase gene controlled by vgb promoter, and an expression vector on which the heterologous gene was under the control of a t7 promoter. the results ... | 1999 | 10935165 |
| the metabolic effects of native and transgenic hemoglobins on plants. | the strictly aerobic bacterium vitreoscilla expresses a hemoglobin-like protein, vhb, when subjected to oxygen stress. when expressed in plants, this has several intriguing physiological effects, such as improving the overall growth rate, speeding germination and flowering, and increasing the productivity of certain oxygen-requiring metabolic pathways. although the mechanisms behind the effects of vhb in heterologous hosts are not yet fully characterized, it has been suggested that vhb facilitat ... | 1999 | 10098274 |
| [progress in research of vitreoscilla hemoglobin and vitreoscilla hemoglobin gene]. | vitreoscilla is a gram-negative obligate aerobic bacterium, whose most important property is the ability to produce the vitreoscilla hemoglobin (vhb). vhb is encoded by a single gene called vitreoscilla hemoglobin gene (vgb) containing the natural promoter, and the expression of vgb gene is regulated by dissolved oxygen at the level of transcription. the oxygen binding vhb participate in the metobolism process of cells and make them grow well in the hypoxic habitats. it also facilitates the bact ... | 1999 | 12555532 |
| genetic engineering of serratia marcescens with bacterial hemoglobin gene: effects on growth, oxygen utilization, and cell size. | the bacterial hemoglobin from vitreoscilla has been shown to increase growth yield and yield of genetically engineered product in escherichia coli. to test the generality of this phenomenon, the approximately 560-bp bacterial (vitreoscilla) hemoglobin gene (vgb) (including the native promoter), cloned into the vector puc8 in two constructs containing about 1650 and 850 bp, respectively, of vitreoscilla dna downstream of vgb, was transformed into serratia marcescens. after several transfers of th ... | 1998 | 10099225 |
| metabolic engineering of serratia marcescens with the bacterial hemoglobin gene: alterations in fermentation pathways. | serratia marcescens was transformed with plasmid vector puc8 or puc8 containing the bacterial (vitreoscilla) hemoglobin gene (vgb) on either a 2.3-kb fragment (puc8:15) or 1.4-kb fragment (puc8:16) of vitreoscilla dna. the vgb-bearing strains were compared with the puc8 transformant and untransformed s. marcescens with respect to growth in luria-bertani (lb) broth supplemented with glucose or casein acid hydrolysate. growth (on a viable cell basis) was similar to that in unsupplemented lb. total ... | 1998 | 10099382 |
| site-directed mutagenesis of bacterial hemoglobin: the role of glutamine (e7) in oxygen-binding in the distal heme pocket. | the bacterial and yeast hemoglobins have a glutamine instead of histidine in the e7 position of the distal heme pocket. the recently determined crystal structure of vitreoscilla hemoglobin (vhb) indicates that this residue is oriented out of the heme pocket and may not ligand the bound oxygen. this is in contrast to elephant myoglobin which also has a gln(e7) but which does ligand the bound oxygen. this residue was changed in vhb using site-directed mutagenesis to leucine (vhbl) or to histidine ... | 1998 | 9439594 |
| hemoglobin biosynthesis in vitreoscilla stercoraria dw: cloning, expression, and characterization of a new homolog of a bacterial globin gene. | in the strictly aerobic, gram-negative bacterium vitreoscilla strain c1, oxygen-limited growth conditions create a more than 50-fold increase in the expression of a homodimeric heme protein which was recognized as the first bacterial hemoglobin (hb). the recently determined crystal structure of vitreoscilla hb has indicated that the heme pocket of microbial globins differs from that of eukaryotic hbs. in an attempt to understand the diverse functions of hb-like proteins in prokaryotes, we have c ... | 1998 | 9603838 |
| improved erythromycin production in a genetically engineered industrial strain of saccharopolyspora erythraea. | an industrial erythromycin production strain of saccharopolyspora erythraea spp. was used to demonstrate that careful genetic engineering can significantly improve productivity. the chromosomally integrated vitreoscilla hemoglobin gene (vhb) was shown to enhance the final titer of erythromycin by some 70% compared to the original s. erythraea spp. overall, specific erythromycin yields were about 2.5 g of erythromycin/g of total protein for s. erythraea::vhb but <1 for the s. erythraea spp. the m ... | 1998 | 9694676 |
| genetic engineering of an industrial strain of saccharopolyspora erythraea for stable expression of the vitreoscilla haemoglobin gene (vhb). | several actinomycetes/streptomycetes expression vectors are described for expression of the vitreoscilla haemoglobin gene (vhb) in an industrial erythromycin-producing strain of saccharopolyspora erythraea. cloning of vhb under the control of either the thiostrepton-inducible ptipa promoter or the constitutive perme* promoter led to the production of chemically active haemoglobin (vhb) in streptomyces lividans tk24 transformed with these constructs. however, theplasmids could not be transformed ... | 1998 | 9782491 |
| expression, purification, crystallization, and preliminary x-ray diffraction analysis of the homodimeric bacterial hemoglobin from vitreoscilla stercoraria. | the recombinant homodimeric hemoglobin from the strictly aerobe gram-negative bacterium vitreoscilla stercoraria has been expressed in escherichia coli, purified to homogeneity, and crystallized by vapor diffusion techniques, using ammonium sulfate as precipitant. the crystals belong to the monoclinic space group p2(1) and diffract to high resolution. the unit cell parameters are alpha = 62.9, b = 42.5, c = 63.2 a, beta = 106.6 degrees; the asymmetric unit contains the homodimeric hemoglobin, wi ... | 1997 | 9037720 |
| transgenic tobacco expressing vitreoscilla hemoglobin exhibits enhanced growth and altered metabolite production. | the gene for vitreoscilla hemoglobin (vhb) has been introduced and expressed in nicotiana tabaccum (tobacco). transgenic tobacco plants expressing vhb exhibited enhanced growth, on average 80-100% more dry weight after 35 days of growth compared to wild-type controls. furthermore, germination time is reduced from 6-8 days for wild-type tobacco to 3-4 days and the growth phase from germination to flowering was 3-5 days shorter for the vhb-expressing transgenes. transgenic plants contained, on ave ... | 1997 | 9062923 |
| unusual structure of the oxygen-binding site in the dimeric bacterial hemoglobin from vitreoscilla sp. | the first hemoglobin identified in bacteria was isolated from vitreoscilla stercoraria (vthb) as a homodimeric species. the wild-type protein has been reported to display medium oxygen affinity and cooperative ligand-binding properties. moreover, vthb can support aerobic growth in escherichia coli with impaired terminal oxidase function. this ability of vthb to improve the growth properties of e. coli has important applications in fermentation technology, assisting the overexpression of recombin ... | 1997 | 9115439 |
| role of the hema gene product and delta-aminolevulinic acid in regulation of escherichia coli heme synthesis. | we initiated these studies to help clarify the roles of heme, delta-aminolevulinic acid (ala), hema, and hemm in escherichia coli heme synthesis. using recombinant human hemoglobin (rhb1.1) as a tool for increasing e. coli's heme requirements, we demonstrated that heme is a feedback inhibitor of heme synthesis. cooverexpression of rhb1.1 and the hema-encoded glutamyl-trna (gtr) reductase increased intracellular levels of ala and heme and increased the rate of rhb1.1 formation. these results supp ... | 1997 | 9226269 |
| bacterial flavohaemoglobins: a consensus sequence and identification of a discrete enterobacterial group and of further bacterial globins. | the amino acid sequences of haemoglobin-like proteins from the bacteria alcaligenes eutrophus, bacillus subtilis, erwinia chrysanthemi, escherichia coli, vibrio parahaemolyticus, vitreoscilla sp. and the yeast saccharomyces cerevisiae were studied. phylogenies based on distance and parsimony analysis showed that the eubacterial group can be easily distinguished from the other haemoglobin-like proteins. the construction of a consensus bacterial flavohaemoglobin based on the alignment of six bacte ... | 1997 | 9351199 |
| globins in nonvertebrate species: dispersal by horizontal gene transfer and evolution of the structure-function relationships. | using a new template based on an alignment of 145 nonvertebrate globins we examined several recently determined sequences of putative globins and globin-like hemeproteins. we propose that all globins have evolved from a family of ancestral, approx. 17-kda hemeproteins, which displayed the globin fold and functioned as redox proteins. once atmospheric o2 became available the acquisition of oxygen-binding properties was initiated, culminating in the various highly specialized functions known as pr ... | 1996 | 8587498 |
| a pbrint family of plasmids for integration of cloned dna into the escherichia coli chromosome. | plasmid pbrint is an efficient vector for chromosomal integration of cloned dna into the lacz gene of escherichia coli [balbás et al., gene 136(1993) 211-213]. a family of related plasmids containing different antibiotic-resistance markers (cmr or gmr or kmr) and a larger multiple cloning site (mcs) has been constructed. this set of plasmids, whose integration efficiencies are as good as those obtained with the prototype plasmid pbrint, constitutes a collection of tools that allow rapid and easy ... | 1996 | 8654993 |
| na(+)-translocating cytochrome bo terminal oxidase from vitreoscilla: some parameters of its na+ pumping and orientation in synthetic vesicles. | vitreoscilla cytochrome bo ubiquinol oxidase is similar in some properties to the escherichia coli enzyme, but unlike the latter, the vitreoscilla oxidase functions as a primary na+ pump. when purified vitreoscilla cytochrome bo is incorporated into liposomes made from vitreoscilla phospholipids and energized with a quinol substrate, it translocates na+, not h+, across the vesicle membrane. since protonophores cccp (carbonyl cyanide m-chlorophenylhydrazone) and dthb (3,5-di-tert-butyl-4-hydroxyb ... | 1996 | 8794772 |
| intracellular expression of vitreoscilla hemoglobin (vhb) enhances total protein secretion and improves the production of alpha-amylase and neutral protease in bacillus subtilis. | in an attempt to alleviate oxygen limitation during batch cultivations, a heterologous bacterial hemoglobin gene (vhb) of vitreoscilla was introduced into bacillus subtilis. biochemically active vhb, as demonstrated by immunoblot analysis and carbon monoxide binding assay, was intracellularly expressed in b. subtilis from an inducible promoter-repressor (spac-laci). expression of vhb in oxygen-limited b. subtilis batch bioreactor cultivations enhanced cell growth, decreased accumulation of aceta ... | 1996 | 8845107 |
| recombinant acremonium chrysogenum strains for the industrial production of cephalosporin. | conventional strain improvement programs based on random mutagenesis and rational screening have meant valuable results to the antibiotic producing companies. the development of recombinant dna techniques and their applications to the industrially-used cephalosporin-producing fungus acremonium chrysogenum has provided a new tool, complementary to classical mutation, promoting the design of alternative biosynthetic pathways making it possible to obtain new antibiotics and to improve cephalosporin ... | 1996 | 8897416 |
| genetic transformation of vitreoscilla sp. | of all the methods customarily used to transform e. coli we found only electroporation to be effective for transformation of the gram-negative bacterium vitreoscilla, yielding 5.10(5) transformants/microgram of plasmid dna. the conditions used were close to those described for e. coli e. coli plasmids are stably maintained in vitreoscilla. this is the first report of exogenous dna transfer in vitreoscilla which opens the way for the application of recombinant-dna techniques to study this unique ... | 1996 | 8921878 |
| expression of vitreoscilla hemoglobin is superior to horse heart myoglobin or yeast flavohemoglobin expression for enhancing escherichia coli growth in a microaerobic bioreactor. | expression of a gene encoding hemoglobin (vhb) from the aerobic bacterium vitreoscilla sp. in several organisms, including escherichia coli, has been shown to improve microaerobic cell growth and enhance oxygen-dependent product formation. the suitability of vhb to enhance microaerobic metabolism has been suggested to depend on its unusual oxygen binding characteristics. to examine whether hemoproteins of other origins can also elicit the positive effects vhb exerts in microaerobic e. coli cells ... | 1996 | 8983204 |
| genetic engineering to contain the vitreoscilla hemoglobin gene enhances degradation of benzoic acid by xanthomonas maltophilia. | xanthomonas maltophilia was transformed with the gene encoding vitreoscilla (bacterial) hemoglobin, vgb, and the growth of the engineered strain was compared with that of the untransformed strain using benzoic acid as the sole carbon source. in general, growth of the engineered strain was greater than that of the untransformed strain; this was true for experiments using both overnight cultures and log phase cells as inocula, but particularly for the latter. in both cases the engineered strain wa ... | 1996 | 18623559 |
| effect of vitreoscilla hemoglobin dosage on microaerobic escherichia coli carbon and energy metabolism. | the amount of vitreoscilla hemoglobin (vhb) expression was modulated over a broad range with an isopropyl-beta-d-thiogalactopyranoside- (iptg-) inducible plasmid, and the consequences on microaerobic escherichia coli physiology were examined in glucose fed-batch cultivations. the effect of iptg induction on growth under oxygen-limited conditions was most visible during late fed-batch phase where the final cell density increased initially linearly with increasing vhb concentrations, ultimately sa ... | 1996 | 18623564 |
| intracellular expression of vitreoscilla hemoglobin modifies microaerobic escherichia coli metabolism through elevated concentration and specific activity of cytochrome o. | the function of the reversible oxygen-binding hemoprotein from vitreoscilla (vhb), which enhances oxygen-limited cell growth and recombinant protein production when functionally expressed in escherichia coli, was investigated in wild-type e. coli and in e. coli mutants lacking one of the two terminal oxidases, cytochrome o complex (aerobic terminal oxidase, cyo) or cytochrome d complex (microaerobic terminal oxidase, cyd). deconvolution of vhb, cytochrome o, and cytochrome d bands from in vivo a ... | 1996 | 18623565 |
| improvement of escherichia coli microaerobic oxygen metabolism by vitreoscilla hemoglobin: new insights from nad(p)h fluorescence and culture redox potential. | on-line nad(p)h fluorescence and culture redox potential (crp) measurements were utilized to investigate the role of vitreoscilla hemoglobin (vhb) in perturbing oxygen metabolism of microaerobic escherichia coli batch cultures of a vhb-synthesizing e. coli strain and the iso-genic control under fully aerated conditions were subject to several high/low oxygen transitions, and the nad(p)h fluorescence and crp were monitored during these passages. the presence of vhb decreased the rate of net nad(p ... | 1995 | 18623410 |
| distribution of the flavohaemoglobin, hmp, between periplasm and cytoplasm in escherichia coli. | the subcellular distribution of the soluble flavohaemoglobin (hmp) of escherichia coli has been determined. cells over-expressing hmp from the cloned hmp gene on a multicopy plasmid were fractionated by osmotic shock and lysozyme treatment. spectral analysis of subcellular fractions showed the co-binding haemoprotein to be cytoplasmic. however, western blotting using antibody raised to purified hmp revealed approximately 30% of the protein to be periplasmic in the over-expressing strain. western ... | 1995 | 7875569 |