| cloning, sequencing, and expression of the zymomonas mobilis fructokinase gene and structural comparison of the enzyme with other hexose kinases. | the frk gene encoding the enzyme fructokinase (fructose 6-phosphotransferase [ec 2.7.1.4]) from zymomonas mobilis has been isolated on a partial taqi digest fragment of the genome and sequenced. an open reading frame of 906 bp corresponding to 302 amino acids was identified on a 3-kbp taqi fragment. the deduced amino acid sequence corresponds to the first 20 amino acids (including an n-terminal methionine) determined by amino acid sequencing of the purified protein. the 118 bp preceding the meth ... | 1992 | 1317376 |
| immunocytochemical localization of glycolytic and fermentative enzymes in zymomonas mobilis. | gold-labeled antibodies were used to examine the subcellular locations of 11 glycolytic and fermentative enzymes in zymomonas mobilis. glucose-fructose oxidoreductase was clearly localized in the periplasmic region. phosphogluconate lactonase and alcohol dehydrogenase i were concentrated in the cytoplasm near the plasma membrane. the eight remaining enzymes were more evenly distributed within the cytoplasmic matrix. selected enzyme pairs were labeled on opposite sides of the same thin section to ... | 1992 | 1320611 |
| mechanism of glutamate uptake in zymomonas mobilis. | the energetics of the anaerobic gram-negative bacterium zymomonas mobilis, a well-known ethanol-producing organism, is based solely on synthesis of 1 mol of atp per mol of glucose by the entner-doudoroff pathway. when grown in the presence of glucose as a carbon and energy source, z. mobilis had a cytosolic atp content of 3.5 to 4 mm. because of effective ph homeostasis, the components of the proton motive force strongly depended on the external ph. at ph 5.5, i.e., around the optimal ph for gro ... | 1992 | 1332937 |
| coordination of expression of zymomonas mobilis glycolytic and fermentative enzymes: a simple hypothesis based on mrna stability. | although zymomonas mobilis is prototrophic, glycolytic and fermentative enzymes (ethanologenic enzymes) constitute over half of the cytoplasmic protein. in this study, transcript stability, functional message pools, and the abundance of cytoplasmic products were compared for genes encoding eight of these essential enzymes. the transcripts of all were very stable, with half-lives ranging from 8 to 18 min. this transcript stability is proposed as an important feature in z. mobilis that may disting ... | 1992 | 1400196 |
| molecular characterization of the zymomonas mobilis enolase (eno) gene. | the zymomonas mobilis gene encoding enolase was cloned by genetic complementation of an escherichia coli eno mutant. an enzyme assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the overexpression of enolase in e. coli clones carrying the z. mobilis eno gene. the eno gene is present in a single copy of the z. mobilis genome. nucleotide sequence analysis of the eno region revealed an open reading frame of 1,293 bp that encodes a protein of 428 amino acids with a predict ... | 1992 | 1400207 |
| use of the tac promoter and laciq for the controlled expression of zymomonas mobilis fermentative genes in escherichia coli and zymomonas mobilis. | the zymomonas mobilis genes encoding alcohol dehydrogenase i (adha), alcohol dehydrogenase ii (adhb), and pyruvate decarboxylase (pdc) were overexpressed in escherichia coli and z. mobilis by using a broad-host-range vector containing the tac promoter and the laciq repressor gene. maximal iptg (isopropyl-beta-d-thiogalactopyranoside) induction of these plasmid-borne genes in z. mobilis resulted in a 35-fold increase in alcohol dehydrogenase i activity, a 16.7-fold increase in alcohol dehydrogena ... | 1992 | 1429459 |
| cloning, sequence analysis, and expression of the structural gene encoding glucose-fructose oxidoreductase from zymomonas mobilis. | the gene encoding glucose-fructose oxidoreductase (gfo) from zymomonas mobilis was cloned in escherichia coli and sequenced. an open reading frame of 439 amino acids encoded a protein of 49 kda. a leader sequence of 52 amino acids preceded the n-terminal sequence of the enzyme, indicating cleavage of the precursor protein at an ala-ala site to give rise to an active form of the enzyme of 43 kda. processing of the glucose-fructose oxidoreductase leader sequence, although not complete, was demonst ... | 1992 | 1537789 |
| the zymomonas mobilis glf, zwf, edd, and glk genes form an operon: localization of the promoter and identification of a conserved sequence in the regulatory region. | the zymomonas mobilis genes that encode the glucose-facilitated diffusion transporter (glf), glucose-6-phosphate dehydrogenase (zwf), 6-phosphogluconate dehydratase (edd), and glucokinase (glk) are clustered on the genome. the data presented here firmly establish that the glf, zwf, edd, and glk genes form an operon, in that order. the four genes of the operon are cotranscribed on a 6.14-kb mrna. the site of transcriptional initiation for the polycistronic message was mapped by primer extension a ... | 1992 | 1569013 |
| the polycistronic mrna of the zymomonas mobilis glf-zwf-edd-glk operon is subject to complex transcript processing. | the full-length 6.14-kb polycistronic glf-zwf-edd-glk mrna from zymomonas mobilis appears to be processed by endonucleolytic cleavage, resulting in the formation of several discrete transcripts. northern analysis and transcript mapping revealed that the processed transcripts correspond to functional mono-, di-, or tricistronic messages. the relative abundance of the gene-specific, functional messages was measured. expression of zwf and edd correlated well with functional message levels. dispropo ... | 1992 | 1569014 |
| molecular characterization of the entner-doudoroff pathway in escherichia coli: sequence analysis and localization of promoters for the edd-eda operon. | the nucleotide sequence of the entire escherichia coli edd-eda region that encodes the enzymes of the entner-doudoroff pathway was determined. the edd structural gene begins 236 bases downstream of zwf. the eda structural gene begins 34 bases downstream of edd. the edd reading frame is 1,809 bases long and encodes the 602-amino-acid, 64,446-da protein 6-phosphogluconate dehydratase. the deduced primary amino acid sequences of the e. coli and zymomonas mobilis dehydratase enzymes are highly conse ... | 1992 | 1624451 |
| ethanol production from cellobiose, amorphous cellulose, and crystalline cellulose by recombinant klebsiella oxytoca containing chromosomally integrated zymomonas mobilis genes for ethanol production and plasmids expressing thermostable cellulase genes from clostridium thermocellum. | the zymomonas mobilis genes for ethanol production have been integrated into the chromosome of klebsiella oxytoca m5a1. the best of these constructs, strain p2, produced ethanol efficiently from cellobiose in addition to monomeric sugars. utilization of cellobiose and cellotriose by this strain eliminated the requirement for external beta-glucosidase and reduced the amount of commercial cellulase needed to ferment solka floc sw40 (primarily crystalline cellulose). the addition of plasmids encodi ... | 1992 | 1637151 |
| segmental message stabilization as a mechanism for differential expression from the zymomonas mobilis gap operon. | in zymomonas mobilis, three- to fourfold more glyceraldehyde-3-phosphate dehydrogenase protein than phosphoglycerate kinase is needed for glycolysis because of differences in catalytic efficiency. consistent with this requirement, higher levels of glyceraldehyde-3-phosphate dehydrogenase were observed with two-dimensional polyacrylamide gel electrophoresis. the genes encoding these enzymes (gap and pgk, respectively) form a bicistronic operon, and some form of regulation is required to provide t ... | 1991 | 1702780 |
| cloning, characterization, and nucleotide sequence analysis of a zymomonas mobilis phosphoglucose isomerase gene that is subject to carbon source-dependent regulation. | the zymomonas mobilis gene encoding phosphoglucose isomerase (pgi) was cloned by genetic complementation of an escherichia coli pgi mutant. an enzyme assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the presence of excess amounts of phosphoglucose isomerase in e. coli clones carrying the z. mobilis pgi gene. the pgi gene is present in only one copy on the z. mobilis genome. nucleotide sequence analysis of the pgi region revealed an open reading frame of 1,524 bp prec ... | 1991 | 1708765 |
| metabolic engineering of klebsiella oxytoca m5a1 for ethanol production from xylose and glucose. | the efficient diversion of pyruvate from normal fermentative pathways to ethanol production in klebsiella oxytoca m5a1 requires the expression of zymomonas mobilis genes encoding both pyruvate decarboxylase and alcohol dehydrogenase. final ethanol concentrations obtained with the best recombinant, strain m5a1 (ploi555), were in excess of 40 g/liter with an efficiency of 0.48 g of ethanol (xylose) and 0.50 g of ethanol (glucose) per g of sugar, as compared with a theoretical maximum of 0.51 g of ... | 1991 | 1746941 |
| expression of an l-alanine dehydrogenase gene in zymomonas mobilis and excretion of l-alanine. | an approach to broaden the product range of the ethanologenic, gram-negative bacterium zymomonas mobilis by means of genetic engineering is presented. gene alad for l-alanine dehydrogenase (ec 1.4.1.1.) from bacillus sphaericus was cloned and introduced into z. mobilis. under the control of the strong promoter of the pyruvate decarboxylase (pdc) gene, the enzyme was expressed up to a specific activity of nearly 1 mu mol . min -1 . mg of protein -1 in recombinant cells. as a results of this high ... | 1991 | 1854197 |
| production of beta-carotene in zymomonas mobilis and agrobacterium tumefaciens by introduction of the biosynthesis genes from erwinia uredovora. | the erwinia uredovora crtb, crte, crti, and crty genes required for beta-carotene biosynthesis were introduced by conjugal transfer into an ethanol-producing bacterium, zymomonas mobilis, and a phytopathogenic bacterium, agrobacterium tumefaciens, in which no carotenoid is synthesized. the transconjugants of z. mobilis and a. tumefaciens carrying these genes appeared as yellow colonies and produced 220 and 350 micrograms of beta-carotene per g of dry weight, respectively, in the stationary phase ... | 1991 | 1872613 |
| content and composition of hopanoids in zymomonas mobilis under various growth conditions. | by using a new method for quantification of the different hopanoid derivatives, a total hopanoid content of about 30 mg/g (dry cell weight) was observed in zymomonas mobilis. this value is the highest reported for bacteria so far. the major hopanoids in z. mobilis were the ether and glycosidic derivatives of tetrahydroxy-bacteriohopane, constituting about 41 and 49% of the total hopanoids. tetrahydroxybacteriohopane itself, diplopterol, and hopene made up about 6, 3, and 1%, respectively. only m ... | 1991 | 1885538 |
| gel electrophoretic analysis of zymomonas mobilis glycolytic and fermentative enzymes: identification of alcohol dehydrogenase ii as a stress protein. | the 13 major enzymes which compose the glycolytic and fermentative pathways in zymomonas mobilis are particularly abundant and represent one-half of the soluble protein in exponential-phase cells. one- and two-dimensional polyacrylamide gel electrophoresis maps were developed for 12 of these enzymes. assignments were made by comigration with purified proteins, comparison with overexpressed genes in recombinant strains, and western blots (immunoblots). although most glycolytic enzymes appeared re ... | 1991 | 1917831 |
| pyruvate decarboxylase from zymomonas mobilis. structure and re-activation of apoenzyme by the cofactors thiamin diphosphate and magnesium ion. | to study the mechanism of re-activation of zymomonas mobilis pyruvate decarboxylase apoenzyme by its cofactors thiamin diphosphate and mg2+, cofactor-free enzyme was prepared by dialysis against 1 mm-dipicolinic acid at ph 8.2. this apoenzyme was then used in a series of experiments that included determination of: (a) the affinity towards one cofactor when the other was present at saturating concentrations; (b) cofactor-binding rates by measuring the quenching of tryptophan fluorescence on the a ... | 1991 | 2049073 |
| genetic improvement of escherichia coli for ethanol production: chromosomal integration of zymomonas mobilis genes encoding pyruvate decarboxylase and alcohol dehydrogenase ii. | zymomonas mobilis genes for pyruvate decarboxylase (pdc) and alcohol dehydrogenase ii (adhb) were integrated into the escherichia coli chromosome within or near the pyruvate formate-lyase gene (pfl). integration improved the stability of the z. mobilis genes in e. coli, but further selection was required to increase expression. spontaneous mutants were selected for resistance to high level of chloramphenicol that also expressed high levels of the z. mobilis genes. analogous mutants were selected ... | 1991 | 2059047 |
| activation of the lac genes of tn951 by insertion sequences from pseudomonas cepacia. | we have identified three transposable gene-activating elements from pseudomonas cepacia on the basis of their abilities to increase expression of the lac genes of the broad-host-range plasmid pgc91.14 (prp1::tn951). when introduced into auxotrophic derivatives of p. cepacia 249 (atcc 17616), this plasmid failed to confer the ability to utilize lactose. the lac genes of tn951 were poorly expressed in p. cepacia and were not induced by isopropyl-beta-d-thiogalactopyranoside. lac+ variants of the p ... | 1990 | 2156800 |
| cloning of the zymomonas mobilis structural gene encoding alcohol dehydrogenase i (adha): sequence comparison and expression in escherichia coli. | zymomonas mobilis ferments sugars to produce ethanol with two biochemically distinct isoenzymes of alcohol dehydrogenase. the adha gene encoding alcohol dehydrogenase i has now been sequenced and compared with the adhb gene, which encodes the second isoenzyme. the deduced amino acid sequences for these gene products exhibited no apparent homology. alcohol dehydrogenase i contained 337 amino acids, with a subunit molecular weight of 36,096. based on comparisons of primary amino acid sequences, th ... | 1990 | 2185223 |
| cloning and sequencing of the saca gene: characterization of a sucrase from zymomonas mobilis. | the zymomonas mobilis gene (saca) encoding a protein with sucrase activity has been cloned in escherichia coli and its nucleotide sequence has been determined. potential ribosome-binding site and promoter sequences were identified in the region upstream of the gene which were homologous to e. coli and z. mobilis consensus sequences. extracts from e. coli cells, containing the saca gene, displayed a sucrose-hydrolyzing activity. however, no transfructosylation activity (exchange reaction or levan ... | 1990 | 2254250 |
| sequence and genetic organization of a zymomonas mobilis gene cluster that encodes several enzymes of glucose metabolism. | the zymomonas mobilis genes that encode glucose-6-phosphate dehydrogenase (zwf), 6-phosphogluconate dehydratase (edd), and glucokinase (glk) were cloned independently by genetic complementation of specific defects in escherichia coli metabolism. the identity of these cloned genes was confirmed by various biochemical means. nucleotide sequence analysis established that these three genes are clustered on the genome and revealed an additional open reading frame in this region that has significant a ... | 1990 | 2254282 |
| nucleotide sequence of the zymomonas mobilis alcohol dehydrogenase ii gene. | | 1990 | 2308827 |
| inactivation of pyruvate decarboxylase by 3-hydroxypyruvate. | pyruvate decarboxylase from zymomonas mobilis is inhibited by 3-hydroxypyruvate, which can also act as a poor substrate. while catalysing the decarboxylation of this alternative substrate, the enzyme undergoes a progressive but partial inactivation over several hours. the extent of inactivation depends upon the ph and upon the concentration of 3-hydroxypyruvate. after partial inactivation and removal of unchanged 3-hydroxypyruvate, enzymic activity recovers slowly. we suggest that inactivation r ... | 1990 | 2310379 |
| expression of zymomonas mobilis adhb (encoding alcohol dehydrogenase ii) and adhb-lacz operon fusions in recombinant z. mobilis. | the zymomonas mobilis alcohol dehydrogenase ii gene (adhb) was overexpressed 7- to 14-fold on a recombinant plasmid, accompanied by a small decrease in growth rate. a fragment containing the truncated gene with promoter reduced expression from the chromosomal gene as measured immunologically and enzymatically, consistent with the presence of a trans-active regulatory factor and positive regulatory control. both the complete gene and the promoter fragment increased pyruvate decarboxylase and gluc ... | 1989 | 2504692 |
| prokaryotic triterpenoids. a novel hopanoid from the ethanol-producing bacterium zymomonas mobilis. | among the triterpenoids of the bacterium zymomonas mobilis a novel hopanoid, 32-oxobacteriohopane-33,34,35-triol beta-linked via its primary hydroxy group to glucosamine, has been isolated as a minor compound. | 1989 | 2640564 |
| similarity of escherichia coli propanediol oxidoreductase (fuco product) and an unusual alcohol dehydrogenase from zymomonas mobilis and saccharomyces cerevisiae. | the gene that encodes 1,2-propanediol oxidoreductase (fuco) from escherichia coli was sequenced. the reading frame specified a protein of 383 amino acids (including the n-terminal methionine), with an aggregate molecular weight of 40,642. the induction of fuco transcription, which occurred in the presence of fucose, was confirmed by northern blot analysis. in e. coli, the primary fuco transcript was approximately 2.1 kilobases in length. the 5' end of the transcript began more than 0.7 kilobase ... | 1989 | 2661535 |
| efficient ethanol production from glucose, lactose, and xylose by recombinant escherichia coli. | lactose and all of the major sugars (glucose, xylose, arabinose, galactose, and mannose) present in cellulose and hemicellulose were converted to ethanol by recombinant escherichia coli containing plasmid-borne genes encoding the enzymes for the ethanol pathway from zymomonas mobilis. environmental tolerances, plasmid stability, expression of z. mobilis pyruvate decarboxylase, substrate range, and ethanol production (from glucose, lactose, and xylose) were compared among eight american type cult ... | 1989 | 2675762 |
| differential expression of gap and pgk genes within the gap operon of zymomonas mobilis. | in zymomonas mobilis, the genes encoding glyceraldehyde-3-phosphate dehydrogenase (gap) and phosphoglycerate kinase (pgk) are encoded in an operon that is transcribed from tandem promoters. the promoter-proximal gap gene is expressed at six- to ninefold higher levels than the pgk gene from chromosomal genes and from multiple copies of plasmid-borne genes. two dominant transcripts were identified. the smaller, most abundant transcript contained primarily the gap message, whereas the larger, less ... | 1989 | 2687242 |
| phosphoglycerate kinase gene from zymomonas mobilis: cloning, sequencing, and localization within the gap operon. | the zymomonas mobilis gene encoding phosphoglycerate kinase (ec 2.7.3.2), pgk, has been cloned into escherichia coli and sequenced. it consists of 336 amino acids, including the n-terminal methionine, with a molecular weight of 41,384. this promoterless gene is located 225 base pairs downstream from the gap gene and is part of the gap operon. previous studies have shown that the specific activities of glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase do not change coordinately ... | 1988 | 2832389 |
| localization and mapping of co2 fixation genes within two gene clusters in rhodobacter sphaeroides. | two fructose 1,6-bisphosphatase structural genes (fbpa and fbpb) have been identified within two unlinked gene clusters that were previously shown to contain the rhodobacter sphaeroides sequences that code for form i and form ii ribulose 1,5-bisphosphate carboxylase-oxygenase and phosphoribulokinase. the fbpa and fbpb genes were localized to a region immediately upstream from the corresponding prka and prkb sequences and were found to be transcribed in the same direction as the phosphoribulokina ... | 1988 | 2834328 |
| cosmid cloning of five zymomonas trp genes by complementation of escherichia coli and pseudomonas putida trp mutants. | a library of zymomonas mobilis genomic dna was constructed in the broad-host-range cosmid plafr1. the library was mobilized into a variety of escherichia coli and pseudomonas putida trp mutants by using the helper plasmid prk2013. five z. mobilis trp genes were identified by the ability to complement the trp mutants. the trpf, trpb, and trpa genes were on one cosmid, while the trpd and trpc genes were on two separate cosmids. the organization of the z. mobilis trp genes seems to be similar to th ... | 1988 | 2838460 |
| comparison of the structural genes for pyruvate decarboxylase in different zymomonas mobilis strains. | the nucleotide sequence of the pyruvate decarboxylase gene from zymomonas mobilis atcc 29191 was determined and compared with the sequence of the corresponding gene in z. mobilis atcc 31821. differences were found, leading to variations on the amino acid level and to different sites for restriction endonucleases. | 1988 | 2838467 |
| modulation of alcohol dehydrogenase isoenzyme levels in zymomonas mobilis by iron and zinc. | zymomonas mobilis is an unusual microorganism which utilizes both iron-containing alcohol dehydrogenase (adhii) and zinc-containing alcohol dehydrogenase (adhi) isoenzymes during fermentative growth. this organism is obligately ethanologenic, and alcohol dehydrogenase activity is essential. the activities of adhi and adhii were altered by supplementing growth medium with iron or zinc salts and by iron starvation. growth under iron-limiting conditions (chelators, minimal medium) reduced adhii act ... | 1989 | 2914864 |
| cloning, sequencing, and characterization of the principal acid phosphatase, the phoc+ product, from zymomonas mobilis. | the zymomonas mobilis gene encoding acid phosphatase, phoc, has been cloned and sequenced. the gene spans 792 base pairs and encodes an mr 28,988 polypeptide. this protein was identified as the principal acid phosphatase activity in z. mobilis by using zymograms and was more active with magnesium ions than with zinc ions. its promoter region was similar to the -35 "pho box" region of the escherichia coli pho genes as well as the regulatory sequences for saccharomyces cerevisiae acid phosphatase ... | 1989 | 2914872 |
| simultaneous purification and characterization of glucokinase, fructokinase and glucose-6-phosphate dehydrogenase from zymomonas mobilis. | the three enzymes glucokinase (ec 2.7.1.2), fructokinase (ec 2.7.1.4) and glucose-6-phosphate dehydrogenase (ec 1.1.1.49) were isolated in high yield from extracts of zymomonas mobilis. the principal steps in the isolation procedures involved the use of selected dye-ligand adsorbent columns, with affinity elution of two of the three enzymes. glucokinase and fructokinase are dimeric proteins (2 x 33000 da and 2 x 28000 da respectively) and glucose-6-phosphate dehydrogenase is a tetramer (4 x 5200 ... | 1985 | 2992451 |
| isolation and properties of the glycolytic enzymes from zymomonas mobilis. the five enzymes from glyceraldehyde-3-phosphate dehydrogenase through to pyruvate kinase. | the five glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, enolase and pyruvate kinase were each purified from extracts of zymomonas mobilis cells, by using dye-ligand chromatography as the principal step. two procedures, producing three and two of the enzymes respectively, are described in detail. z. mobilis glyceraldehyde-phosphate dehydrogenase was found to be similar in most respects to the enzyme from other sources, except for hav ... | 1986 | 3026343 |
| promoter and nucleotide sequences of the zymomonas mobilis pyruvate decarboxylase. | dna sequence analysis showed that pyruvate decarboxylase (one of the most abundant proteins in zymomonas mobilis) contains 559 amino acids. the promoter for the gene encoding pyruvate decarboxylase was not recognized by escherichia coli, although the cloned gene was expressed at relatively high levels under the control of alternative promoters. the promoter region did not contain sequences which could be identified as being homologous to the generalized promoter structure for e. coli. hydropathy ... | 1987 | 3029037 |
| nucleotide sequence of the pyruvate decarboxylase gene from zymomonas mobilis. | pyruvate decarboxylase (ec 4.1.1.1), the penultimate enzyme in the alcoholic fermentation pathway of zymomonas mobilis, converts pyruvate to acetaldehyde and carbon dioxide. the complete nucleotide sequence of the structural gene encoding pyruvate decarboxylase from zymomonas mobilis has been determined. the coding region is 1704 nucleotides long and encodes a polypeptide of 567 amino acids with a calculated subunit mass of 60,790 daltons. the amino acid sequence was confirmed by comparison with ... | 1987 | 3029726 |
| gene expression in zymomonas mobilis: promoter structure and identification of membrane anchor sequences forming functional lacz' fusion proteins. | we have described a procedure for the isolation of lacz' fusion genes which contain anchor sequences conferring membrane association. this method was used to isolate fragments of dna from zymomonas mobilis which contain promoter activity and amino-terminal sequences. the sequences and transcriptional initiation sites of three of these were compared. both escherichia coli and z. mobilis recognized similar regions of dna for transcriptional initiation. five to eight consecutive hydrophobic amino a ... | 1987 | 3034853 |
| model for studying bacterial adherence to skin wounds. | the adherence of bacterial pathogens to wounded skin is probably the first step in wound infection. this report describes the development of a bioassay to simulate the adherence of bacteria to wounds. the adherence of bacteria was examined by exposing wounds to known quantities of pathogens, washing the wounds with distilled water, and quantitating the number of adherent bacteria per cm2 of tissue. our studies focused on the effects of naturally occurring mediators of bacterial adherence, such a ... | 1987 | 3116035 |
| genetic engineering of ethanol production in escherichia coli. | the genes encoding essential enzymes of the fermentative pathway for ethanol production in zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into escherichia coli under the control of a common promoter. alcohol dehydrogenase ii and pyruvate decarboxylase from z. mobilis were expressed at high levels in e. coli, resulting in increased cell growth and the production of ethanol as the principal fermentation product from glucose. these results demonstrate that it is possible to ... | 1987 | 3322191 |
| seroprevalence and association with abortion of leptospirosis in cattle in ontario. | sera were collected using a systematic random sampling from 348 cattle herds in ontario, in proportion to the cattle population in different areas. one cow in five from 296 dairy herds and one in three from 52 beef herds were sampled. the sera were analyzed for prevalence of antibodies to leptospira interrogans serovar grippotyphosa, hardjo, icterohaemorhagiae and pomona using the microscopic agglutination test. herd seroprevalence (one or more animals with titer greater than or equal to 80) in ... | 1988 | 3370556 |
| pyruvate decarboxylase of zymomonas mobilis: isolation, properties, and genetic expression in escherichia coli. | pyruvate decarboxylase (ec 4.1.1.1) from zymomonas mobilis purified to homogeneity by using dye-ligand and ion-exchange chromatography. antibodies produced against the enzyme and the amino-terminal sequence obtained for the pure enzyme were used to select and confirm the identity of a genomic clone encoding the enzyme selected from a genomic library of z. mobilis dna cloned into puc9. the genomic fragment encoding the enzyme expressed high levels of pyruvate decarboxylase in escherichia coli. po ... | 1987 | 3546263 |
| cloning and sequencing of the alcohol dehydrogenase ii gene from zymomonas mobilis. | the gene which encodes alcohol dehydrogenase ii (adhb) from zymomonas mobilis was cloned in escherichia coli as a 1.4-kilobase dna fragment by using a novel indicator plate which directly detects the expression of this activity by recombinant colonies. the dna sequence for this clone contained an open reading frame encoding a polypeptide of 383 amino acids, with a molecular weight of 40,141. although this protein exhibited very little homology with other known alcohol dehydrogenases, the predict ... | 1987 | 3584063 |
| glycolytic flux in zymomonas mobilis: enzyme and metabolite levels during batch fermentation. | the rate at which z. mobilis (entner-doudoroff pathway) converts high concentrations of glucose (20%) into ethanol plus co2 changes as ethanol accumulates in the surrounding broth. this decline in glycolytic activity (per milligram of cell protein) does not result from inhibitory effects of ethanol, which can be reversed immediately by ethanol removal. the peak of fermentative activity (58 mumol of co2 evolved per mg of cell protein per h) occurred after the accumulation of 1.1% ethanol (18 h) a ... | 1987 | 3611027 |
| glyceraldehyde-3-phosphate dehydrogenase gene from zymomonas mobilis: cloning, sequencing, and identification of promoter region. | the gene encoding glyceraldehyde-3-phosphate dehydrogenase was isolated from a library of zymomonas mobilis dna fragments by complementing a deficient strain of escherichia coli. it contained tandem promoters which were recognized by e. coli but appeared to function less efficiently than the enteric lac promoter in e. coli. the open reading frame for this gene encoded 337 amino acids with an aggregate molecular weight of 36,099 (including the n-terminal methionine). the primary amino acid sequen ... | 1987 | 3680173 |
| glucose-fructose oxidoreductase, a new enzyme isolated from zymomonas mobilis that is responsible for sorbitol production. | the enzymes responsible for sorbitol formation in zymomonas mobilis were investigated. a previously undescribed enzyme catalyzes the intermolecular oxidation-reduction of glucose and fructose to form gluconolactone and sorbitol. this enzyme has been purified; it had a subunit size of 40,000 daltons and is probably tetrameric at low ph. it contained tightly bound nadp as the hydrogen carrier and did not require any added cofactor for activity. in addition, a gluconolactonase has been isolated, al ... | 1986 | 3745122 |
| effect of ethanol and heat stresses on the protein pattern of zymomonas mobilis. | heat or ethanol shock of zymomonas mobilis enhanced the labeling by [35s]methionine of several polypeptides and induced the synthesis of a new polypeptide (molecular weight, 18,500) associated with the envelope fraction. these results indicate the existence of a typical heat-shock response in z. mobilis. this response could be involved in the induction of increased ethanol tolerance in z. mobilis cells. | 1986 | 3949711 |
| mechanism of ethanol inhibition of fermentation in zymomonas mobilis cp4. | accumulation of alcohol during fermentation is accompanied by a progressive decrease in the rate of sugar conversion to ethanol. in this study, we provided evidence that inhibition of fermentation by ethanol can be attributed to an indirect effect of ethanol on the enzymes of glycolysis involving the plasma membrane. ethanol decreased the effectiveness of the plasma membrane as a semipermeable barrier, allowing leakage of essential cofactors and coenzymes. this leakage of cofactors and coenzymes ... | 1985 | 4044518 |
| self-transmissible plasmid in zymomonas mobilis carrying antibiotic resistance. | the cryptic plasmid prut41 from zymomonas mobilis was examined for its biological properties. this plasmid was found to be conjugally transferred from z. mobilis cp4 to escherichia coli bm21 and to carry genes for antibiotic resistance (gentamicin, kanamycin, and streptomycin). covalently closed circular plasmid dna was isolated from eight transconjugants of e. coli bm21. these plasmids were identical in mobility on agarose gels and exhibited the same restriction patterns as the native prut41 pl ... | 1984 | 6364969 |
| lipid composition of zymomonas mobilis: effects of ethanol and glucose. | zymomonas mobilis is an alcohol-tolerant microorganism which is potentially useful for the commercial production of ethanol. this organism was found to contain cardiolipin, phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylcholine as major phospholipids. vaccenic acid was the most abundant fatty acid, with lesser amounts of myristic, palmitic, and palmitoleic acids. no branched-chain or cyclopropane fatty acids were found. previous studies in our laboratory have shown that ethanol ... | 1983 | 6853446 |
| minimal medium for isolation of auxotrophic zymomonas mutants. | a minimal medium which allowed the sustained, rapid growth of zymomonas mobilis and the isolation of a range of auxotrophic mutants was developed. | 1982 | 7125659 |
| isolation and sequence analysis of rpoh genes encoding sigma 32 homologs from gram negative bacteria: conserved mrna and protein segments for heat shock regulation. | the rpoh genes encoding homologs of escherichia coli sigma 32 (heat shock sigma factor) were isolated and sequenced from five gram negative proteobacteria (gamma or alpha subgroup): enterobacter cloacae (gamma), serratia marcescens (gamma), proteus mirabilis (gamma), agrobacterium tumefaciens (alpha) and zymomonas mobilis (alpha). comparison of these and three known genes from e.coli (gamma), citrobacter freundii (gamma) and pseudomonas aeruginosa (gamma) revealed marked similarities that should ... | 1995 | 7501460 |
| the glutamate uptake regulatory protein (grp) of zymomonas mobilis and its relation to the global regulator lrp of escherichia coli. | after being expressed in escherichia coli jc5412, which is defective in glutamate transport, a zymomonas mobilis gene which enabled this strain to grow on glutamate was cloned. this gene encodes a protein with 33% amino acid identity to the leucine-responsive regulatory protein (lrp) of e. coli. although overall glutamate uptake in e. coli was increased, the protein encoded by the cloned fragment repressed the secondary h+/glutamate transport system gltp by interaction with the promoter region o ... | 1995 | 7665494 |
| a novel aerobic respiratory chain-linked nadh oxidase system in zymomonas mobilis. | membrane vesicles prepared from zymomonas mobilis oxidized nadh exclusively, whereas deamino-nadh was little oxidized. in addition, the respiratory chain-linked nadh oxidase system exhibited only a single apparent km value of approximately 66 microm for nadh. the nadh oxidase was highly sensitive to the respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-n-oxide. however, the nadh:quinone oxidoreductase was not sensitive to 2-heptyl-4-hydroxyquinoline-n-oxide and was highly resistant to anot ... | 1995 | 7665502 |
| sequence analysis and overexpression of the zymomonas mobilis tgt gene encoding trna-guanine transglycosylase: purification and biochemical characterization of the enzyme. | trna-guanine transglycosylase (tgt) is involved in the biosynthesis of the hypermodified trna nucleoside queuosine (q). it catalyzes the posttranscriptional base exchange of the q precursor 7-aminomethyl-7-deazaguanine (preq1) with the genetically encoded guanine in the anticodon of trna(asp), trna(asn), trna(his), and trna(tyr). a partially sequenced gene upstream of the dna ligase (lig) gene of the zymomonas mobilis chromosome shows strong homology to the tgt gene of escherichia coli (k.b. sha ... | 1995 | 7665516 |
| purification and characterization of an extracellular levansucrase from pseudomonas syringae pv. phaseolicola. | levansucrase (ec 2.4.1.10), an exoenzyme of pseudomonas syringae pv. phaseolicola, was purified to homogeneity from the cell supernatant by chromatography on tmae-fraktogel and butyl-fraktogel. the enzyme has molecular masses of 45 kda under denaturing conditions and 68 kda during gel filtration of the native form. in isoelectric focusing, active bands appeared at ph 3.55 and 3.6. maximum sucrose cleaving activities were measured at ph 5.8 to 6.6 and 60 degrees c. the enzyme was highly tolerant ... | 1995 | 7751294 |
| crystallization and preliminary x-ray analysis of glucose-fructose oxidoreductase from zymomonas mobilis. | glucose-fructose oxidoreductase (e.c. 1.1.99.-) from the ethanol-producing gram-negative bacterium zymomonas mobilis is a periplasmic, soluble enzyme that forms a homotetramer of 160 kda with one nadp(h) cofactor per subunit that is tightly, but noncovalently, bound. the enzyme was crystallized by the hanging drop vapor diffusion method using sodium citrate as precipitant. the obtained crystals belong to the space group p2(1)2(1)2, with unit cell constants of 84.6 a, 94.1 a, and 117.0 a, consist ... | 1994 | 7756998 |
| functional expression of the glucose transporter of zymomonas mobilis leads to restoration of glucose and fructose uptake in escherichia coli mutants and provides evidence for its facilitator action. | the zymomonas mobilis genes encoding the glucose facilitator (glf), glucokinase (glk), or fructokinase (frk) were cloned and expressed in a laciq-ptac system using escherichia coli k-12 mutants deficient in uptake and phosphorylation of glucose and fructose. growth on glucose or fructose was restored when the respective genes (glf-glk or glf-frk) were expressed. in e. coli glf+ strains, both glucose and fructose were taken up via facilitated diffusion (km, 4.1 mm for glucose and 39 mm for fructo ... | 1995 | 7768841 |
| imidazole acetol phosphate aminotransferase in zymomonas mobilis: molecular genetic, biochemical, and evolutionary analyses. | hish encodes imidazole acetol phosphate (iap) aminotransferase in zymomonas mobilis and is located immediately upstream of tyrc, a gene which codes for cyclohexadienyl dehydrogenase. a plasmid containing hish was able to complement an escherichia coli histidine auxotroph which lacked the homologous aminotransferase. dna sequencing of hish revealed an open reading frame of 1,110 bp, encoding a protein of 40,631 da. the cloned hish product was purified from e. coli and estimated by sodium dodecyl ... | 1995 | 7883715 |
| sorbitol promotes growth of zymomonas mobilis in environments with high concentrations of sugar: evidence for a physiological function of glucose-fructose oxidoreductase in osmoprotection. | the gram-negative ethanologenic bacterium zymomonas mobilis is able to grow in media containing high concentrations of glucose or other sugars. a novel compatible solute for bacteria, sorbitol, which enhances growth of z. mobilis at glucose concentrations exceeding 0.83 m (15%), is described. added sorbitol was accumulated intracellularly up to 1 m to counteract high external glucose concentrations (up to 1.66 m or 30%). accumulation of sorbitol was triggered by a glucose upshift (e.g., from 0.3 ... | 1994 | 8002594 |
| ethanolic fermentation in transgenic tobacco expressing zymomonas mobilis pyruvate decarboxylase. | during oxygen limitation in higher plants, energy metabolism switches from respiration to fermentation. as part of this anaerobic response the expression of genes encoding pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adh) is strongly induced. in addition there is ample evidence for post-translational regulation. in order to understand this multi-level regulation of the anaerobic response, we provided tobacco with the constitutive capacity of ethanolic fermentation by expressing a pdc ... | 1994 | 8026460 |
| two genes for carbohydrate catabolism are divergently transcribed from a region of dna containing the hexc locus in pseudomonas aeruginosa pao1. | the hexc locus of pseudomonas aeruginosa pao1 was localized to a 247-bp segment of chromosomal dna on the multicopy broad-host-range vector pro1614. the presence of this plasmid (ppz196) in strain pao1 produced the so-called "hexc effect," a two- to ninefold increase in the activities of four carbohydrate catabolism enzymes, glucokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydratase, and 2-keto-3-deoxy-6-phosphogluconate aldolase. the extent of the hexc effect was restricted, ... | 1994 | 8045900 |
| reconstruction of glucose uptake and phosphorylation in a glucose-negative mutant of escherichia coli by using zymomonas mobilis genes encoding the glucose facilitator protein and glucokinase. | expression of the zymomonas mobilis glf (glucose facilitator protein) and glk (glucokinase) genes in escherichia coli zsc113 (glucose negative) provided a new functional pathway for glucose uptake and phosphorylation. both genes were essential for the restoration of growth in glucose minimal medium and for acid production on glucose-macconkey agar plates. | 1994 | 8144485 |
| investigation of the cofactor-binding site of zymomonas mobilis pyruvate decarboxylase by site-directed mutagenesis. | several enzymes require thiamin diphosphate (thdp) as an essential cofactor, and we have used one of these, pyruvate decarboxylase (pdc; ec 4.1.1.1) from zymomonas mobilis, as a model for this group of enzymes. it is well suited for this purpose because of its stability, ease of purification and its simple kinetic properties. a sequence motif of approx. 30 residues, beginning with a glycine-aspartate-glycine (-gdg-) triplet and ending with a double asparagine (-nn-) sequence, has been identified ... | 1994 | 8198554 |
| isoprenoid biosynthesis in bacteria: a novel pathway for the early steps leading to isopentenyl diphosphate. | incorporation of 13c-labelled glucose, acetate, pyruvate or erythrose allowed the determination of the origin of the carbon atoms of triterpenoids of the hopane series and/or of the ubiquinones from several bacteria (zymomonas mobilis, methylobacterium fujisawaense, escherichia coli and alicyclobacillus acidoterrestris) confirmed our earlier results obtained by incorporation of 13c-labelled acetate into the hopanoids of other bacteria and led to the identification of a novel biosynthetic route f ... | 1993 | 8240251 |
| cloning, sequencing, and expression of the zymomonas mobilis phosphoglycerate mutase gene (pgm) in escherichia coli. | phosphoglycerate mutase is an essential glycolytic enzyme for zymomonas mobilis, catalyzing the reversible interconversion of 3-phosphoglycerate and 2-phosphoglycerate. the pgm gene encoding this enzyme was cloned on a 5.2-kbp dna fragment and expressed in escherichia coli. recombinants were identified by using antibodies directed against purified z. mobilis phosphoglycerate mutase. the pgm gene contains a canonical ribosome-binding site, a biased pattern of codon usage, a long upstream untransl ... | 1993 | 8320209 |
| the aroq-encoded monofunctional chorismate mutase (cm-f) protein is a periplasmic enzyme in erwinia herbicola. | enteric bacteria possess two species of chorismate mutase which exist as catalytic domains on the amino termini of the bifunctional phea and tyra proteins. in addition, some of these organisms possess a third chorismate mutase, cm-f, which exists as a small monofunctional protein. the cm-f gene (denoted aroq) from erwinia herbicola was cloned and sequenced for the first time. a strategy for selection by functional complementation in a chorismate mutase-free escherichia coli background was devise ... | 1993 | 8335631 |
| mutational analysis of segmental stabilization of transcripts from the zymomonas mobilis gap-pgk operon. | in zymomonas mobilis, the genes encoding glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase are transcribed together from the gap-pgk operon. however, higher levels of the former enzyme are present in the cytoplasm because of increased stability of a 5' segment containing the gap coding region. this segment is bounded by an upstream untranslated region which can be folded into many stem-loop structures and a prominent intercistronic stem-loop. mutations eliminating a proposed s ... | 1993 | 8468293 |
| purification and characterization of an oxygen-labile, nad-dependent alcohol dehydrogenase from desulfovibrio gigas. | a nad-dependent, oxygen-labile alcohol dehydrogenase was purified from desulfovibrio gigas. it was decameric, with subunits of m(r) 43,000. the best substrates were ethanol (km, 0.15 mm) and 1-propanol (km, 0.28 mm). n-terminal amino acid sequence analysis showed that the enzyme belongs to the same family of alcohol dehydrogenases as zymomonas mobilis adh2 and bacillus methanolicus mdh. | 1993 | 8491707 |
| cloning and expression in escherichia coli of the dnak gene of zymomonas mobilis. | the dnak protein of zymomonas mobilis (dnakz) was identified and found to be 80% identical to the dnak protein of escherichia coli on the basis of the sequence of the n-terminal 21 amino acids. the dnakz gene was cloned and found to be expressed in a thermosensitive dnak mutant of escherichia coli. expression of the foreign gene restored a thermoresistant phenotype but failed to modulate the heat shock response in e. coli. | 1993 | 8491740 |
| development of a gene reporter system in moderately halophilic bacteria by employing the ice nucleation gene of pseudomonas syringae. | the expression of the ice nucleation gene inaz of pseudomonas syringae in several moderate halophiles was investigated to establish its utility as a reporter for promoter activity and gene expression studies in these biotechnologically and environmentally important bacteria. a promoterless version of inaz was introduced in two different restriction sites and at both orientations in a recombinant plasmid able to replicate in moderate halophiles and, in particular, within the sequence of its phe1 ... | 1995 | 8526492 |
| ethanol transport in zymomonas mobilis measured by using in vivo nuclear magnetic resonance spin transfer. | for the first time, unidirectional rate constants of ethanol diffusion through the lipid membrane of a microorganism, the bacterium zymomonas mobilis, were determined, thus replacing indirect inferences with direct kinetic data. the rate constants k1 (in to out) were 6.8 +/- 0.4s(-1) at 29 degrees c and 2.7 +/- 0.3s(-1) at 20 degrees c. they were determined by using 1h selective nuclear magnetic resonance spin magnetization transfer. the measurements were done on l-ml cell suspensions. no additi ... | 1996 | 8626306 |
| the role of residues glutamate-50 and phenylalanine-496 in zymomonas mobilis pyruvate decarboxylase. | several enzymes require thiamine diphosphate (thdp) as an essential cofactor, and we have used one of these, pyruvate decarboxylase (pdc; ec 4.1.1.1) from zymomonas mobilis, as a model for this group of enzymes. it is well suited for this purpose because of its stability, ease of purification, homotetrameric subunit structure and simple kinetic properties. crystallographic analyses of three thdp-dependent enzymes [müller, lindqvist, furey, schulz, jordan and schneider (1993) structure 1, 95-103] ... | 1996 | 8645153 |
| crystal structure of trna-guanine transglycosylase: rna modification by base exchange. | trna-guanine transglycosylases (tgt) are enzymes involved in the modification of the anticodon of trnas specific for asn, asp, his and tyr, leading to the replacement of guanine-34 at the wobble position by the hypermodified base queuine. in prokaryotes tgt catalyzes the exchange of guanine-34 with the queuine (.)precursor 7-aminomethyl-7-deazaguanine (preq1). the crystal structure of tgt from zymomonas mobilis was solved by multiple isomorphous replacement and refined to a crystallographic r-fa ... | 1996 | 8654383 |
| identification and characterization of phon-sf, a gene on the large plasmid of shigella flexneri 2a encoding a nonspecific phosphatase. | a gene encoding a nonspecific phosphatase, named phon-sf, was identified on the large virulence plasmid (pmysh6000) of shigella flexneri 2a ysh6000. the phosphatase activity in ysh6000 was observed under high-phosphate conditions. however, it was found that low-phosphate conditions induced a slightly higher level of activity. the nucleotide sequence of the phon-sf region cloned from pmysh6000 possessing the phon-sf gene encoded 249 amino acids with a typical signal sequence at the n terminus. th ... | 1996 | 8755883 |
| expression of the escherichia coli pmi gene, encoding phosphomannose-isomerase in zymomonas mobilis, leads to utilization of mannose as a novel growth substrate, which can be used as a selective marker. | wild-type zymomonas mobilis can utilize only three substrates (sucrose, glucose, and fructose) as sole carbon sources, which are largely converted into ethanol and carbon dioxide. here, we show that although d-mannose is not used as a growth substrate, it is taken up via the glucose uniport system (glucose facilitator protein) with a vmax similar to that of glucose. moreover, d-mannose was phosphorylated by a side activity of the resident fructokinase to mannose-6-phosphate. fructokinase was pur ... | 1996 | 8900006 |
| genetic and physiological analysis of the lethal effect of l-(+)-lactate dehydrogenase deficiency in streptococcus mutans: complementation by alcohol dehydrogenase from zymomonas mobilis. | ch4ts is a previously isolated recombinant mutant of streptococcus mutans ng8 which produces a thermolabile l-(+)-lactate dehydrogenase (ldh) activity. it does not grow at 42 degrees c under a variety of cultivation conditions. in this study, we show that a batch culture of ch4ts shifted from 30 to 42 degrees c underwent rapid cessation of growth and accelerated cell death. the mutant grew at 42 degrees c in continuous culture under glucose-limiting conditions. under these conditions, lactate pr ... | 1996 | 8926105 |
| development of an arabinose-fermenting zymomonas mobilis strain by metabolic pathway engineering. | the substrate fermentation range of the ethanologenic bacterium zymomonas mobilis was expanded to include the pentose sugar, l-arabinose, which is commonly found in agricultural residues and other lignocellulosic biomass. five genes, encoding l-arabinose isomerase (araa), l-ribulokinase (arab), l-ribulose-5-phosphate-4-epimerase (arad), transaldolase (talb), and transketolase (tkta), were isolated from escherichia coli and introduced into z. mobilis under the control of constitutive promoters th ... | 1996 | 8953718 |
| stabilization of pet operon plasmids and ethanol production in escherichia coli strains lacking lactate dehydrogenase and pyruvate formate-lyase activities. | in the last decade, a major goal of research in biofuels has been to metabolically engineer microorganisms to ferment multiple sugars from biomass or agricultural wastes to fuel ethanol. escherichia coli strains genetically engineered to contain the pet operon (zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase b genes) produce high levels of ethanol. strains carrying the pet operon in plasmid (e.g., e. coli b/ploi297) or in chromosomal (e.g., e. coli ko11) sites require antibiot ... | 1996 | 8953729 |
| differential inactivation of alcohol dehydrogenase isoenzymes in zymomonas mobilis by oxygen. | zymomonas mobilis is endowed with two isoenzymes of fermentative alcohol dehydrogenase, a zinc-containing enzyme (adh i) and an iron-containing enzyme (adh ii). the activity of adh i remains fully conserved, while adh ii activity decays when anaerobic cultures are shifted to aerobiosis. this differential response depends on the metal present on each isoenzyme, since pure preparations of adh i are resistant to oxidative inactivation and preparations of zinc-containing adh ii, obtained by incubati ... | 1997 | 9023190 |
| allosteric control of zymomonas mobilis glucose-6-phosphate dehydrogenase by phosphoenolpyruvate. | the second enzyme of the entner-doudoroff glycolytic pathway in zymomonas mobilis, glucose-6-phosphate dehydrogenase, has been found to be inhibited by phosphoenolpyruvate (pep). in the presence of pep levels in the micromolar range, the response of the enzyme to glucose 6-phosphate concentration becomes sigmoidal, with a hill coefficient up to 2. at low ionic strength in the absence of pep, the response to glucose 6-phosphate concentration is michaelis-menten, but at physiological ionic strengt ... | 1997 | 9307022 |
| isolation and molecular characterization of high-performance cellobiose-fermenting spontaneous mutants of ethanologenic escherichia coli ko11 containing the klebsiella oxytoca casab operon. | escherichia coli ko11 was previously constructed to produce ethanol from acid hydrolysates of hemicellulose (pentoses and hexoses) by the chromosomal integration of zymomonas mobilis genes encoding pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhb). klebsiella oxytoca p2 was constructed in an analogous fashion for the simultaneous saccharification and fermentation of cellulose and contains pts enzymes for cellobiose. in this study, ko11 was further engineered for the fermentation of c ... | 1997 | 9406380 |
| metabolic roles of a rhodobacter sphaeroides member of the sigma32 family. | we report the role of a gene (rpoh) from the facultative phototroph rhodobacter sphaeroides that encodes a protein (sigma37) similar to escherichia coli sigma32 and other members of the heat shock family of eubacterial sigma factors. r. sphaeroides sigma37 controls genes that function during environmental stress, since an r. sphaeroides deltarpoh mutant is approximately 30-fold more sensitive to the toxic oxyanion tellurite than wild-type cells. however, the deltarpoh mutant lacks several phenot ... | 1998 | 9422586 |
| the sequence of spacers between the consensus sequences modulates the strength of prokaryotic promoters. | we constructed a library of synthetic promoters for lactococcus lactis in which the known consensus sequences were kept constant while the sequences of the separating spacers were randomized. the library consists of 38 promoters which differ in strength from 0.3 up to more than 2,000 relative units, the latter among the strongest promoters known for this organism. the ranking of the promoter activities was somewhat different when assayed in escherichia coli, but the promoters are efficient for m ... | 1998 | 9435063 |
| characterization of glucose-specific catabolite repression-resistant mutants of bacillus subtilis: identification of a novel hexose:h+ symporter. | insertional mutagenesis was conducted on bacillus subtilis cells to screen for mutants resistant to catabolite repression. three classes of mutants that were resistant to glucose-promoted but not mannitol-promoted catabolite repression were identified. cloning and sequencing of the mutated genes revealed that the mutations occurred in the structural genes for (i) enzyme ii of the phosphoenolpyruvate-glucose phosphotransferase (ptsg), (ii) antiterminator glct, which controls ptsg synthesis, and ( ... | 1998 | 9457850 |
| the effects of temperature on the kinetics and stability of mesophilic and thermophilic 3-phosphoglycerate kinases. | the effects of temperature on the kinetic parameters kcat and km, for three isolates of the highly conserved monomeric enzyme 3-phosphoglycerate kinase (pgk), were investigated in detail using a rapid automated kinetics apparatus. pgk was purified from the thermophilic bacterium thermoanaerobacter sp. rt8.g4 (optimum growth temperature 68 degrees c), the mesophile zymomonas mobilis (optimum growth temperature 32 degrees c) and a second, unidentified, soil mesophile designated unid a (optimum gro ... | 1998 | 9494072 |
| production of 1-kestose in transgenic yeast expressing a fructosyltransferase from aspergillus foetidus. | sucrose-inducible secretory sucrose:sucrose 1-fructosyltransferase (1-sst) from aspergillus foetidus has been purified and subjected to n-terminal amino acid sequence determination. the enzyme is extensively glycosylated, and the active form is probably represented by a dimer of identical subunits with an apparent molecular mass of 180 kda as judged from mobility in seminative acrylamide gels. the enzyme catalyzes fructosyl transfer from sucrose to sucrose producing glucose and 1-kestose. oligos ... | 1998 | 9495772 |
| purification of the pyruvate dehydrogenase multienzyme complex of zymomonas mobilis and identification and sequence analysis of the corresponding genes. | the pyruvate dehydrogenase (pdh) complex of the gram-negative bacterium zymomonas mobilis was purified to homogeneity. from 250 g of cells, we isolated 1 mg of pdh complex with a specific activity of 12.6 u/mg of protein. analysis of subunit composition revealed a pdh (e1) consisting of the two subunits e1alpha (38 kda) and e1beta (56 kda), a dihydrolipoamide acetyltransferase (e2) of 48 kda, and a lipoamide dehydrogenase (e3) of 50 kda. the e2 core of the complex is arranged to form a pentagona ... | 1998 | 9515924 |
| buffering capacity and membrane h+ conductance of neutrophilic and alkalophilic gram-positive bacteria. | buffering capacity and membrane h+ conductance were examined in three gram-positive bacteria, staphylococcus aureus, bacillus subtilis, and bacillus alcalophilus. an acid pulse technique was used to measure both parameters. the buffering capacity and membrane h+ conductance of b. alcalophilus are influenced by the ph of the medium and the culture conditions. suspensions of b. alcalophilus cells from both h. a. medium and l-malate medium cultures grown at ph 10.5 exhibited higher values for these ... | 1998 | 9546171 |
| pichia stipitis genes for alcohol dehydrogenase with fermentative and respiratory functions. | two genes coding for isozymes of alcohol dehydrogenase (adh); designated psadh1 and psadh2, have been identified and isolated from pichia stipitis cbs 6054 genomic dna by southern hybridization to saccharomyces cerevisiae adh genes, and their physiological roles have been characterized through disruption. the amino acid sequences of the psadh1 and psadh2 isozymes are 80.5% identical to one another and are 71.9 and 74.7% identical to the s. cerevisiae adh1 protein. they also show a high level ide ... | 1998 | 9546172 |
| effects of pyruvate decarboxylase overproduction on flux distribution at the pyruvate branch point in saccharomyces cerevisiae. | a multicopy plasmid carrying the pdc1 gene (encoding pyruvate decarboxylase; pdc) was introduced in saccharomyces cerevisiae cen. pk113-5d. the physiology of the resulting prototrophic strain was compared with that of the isogenic prototrophic strain cen.pk113-7d and an empty-vector reference strain. in glucose-grown shake-flask cultures, the introduction of the pdc1 plasmid caused a threefold increase in the pdc level. in aerobic glucose-limited chemostat cultures growing at a dilution rate of ... | 1998 | 9603825 |
| cloning of the lactococcus lactis adhe gene, encoding a multifunctional alcohol dehydrogenase, by complementation of a fermentative mutant of escherichia coli. | the lactococcus lactis adhe gene, which encodes a multifunctional alcohol dehydrogenase, has been cloned and characterized. a dna fragment encoding the putative alcohol dehydrogenase domain of the adhe protein was cloned by screening an l. lactis genomic library in a fermentative mutant of escherichia coli and selecting for the ability to grow anaerobically. further analysis of the clone obtained allowed the cloning of the entire adhe gene sequence. analysis of adhe expression in l. lactis durin ... | 1998 | 9620952 |
| cloning and expression of the listeria monocytogenes scott a ptsh and ptsi genes, coding for hpr and enzyme i, respectively, of the phosphotransferase system. | the phosphoenolpyruvate (pep)-dependent phosphotransferase system (pts) utilizes high-energy phosphate present in pep to drive the uptake of several different carbohydrates in bacteria. in order to examine the role of the pts in the physiology of listeria monocytogenes, we identified the ptsh and ptsi genes encoding the hpr and enzyme i proteins, respectively, of the pts. nucleotide sequence analysis indicated that the predicted proteins are nearly 70% similar to hpr and enzyme i proteins from o ... | 1998 | 9726852 |
| cloning, nucleotide sequence, and expression in escherichia coli of levansucrase genes from the plant pathogens pseudomonas syringae pv. glycinea and p. syringae pv. phaseolicola. | plant-pathogenic bacteria produce various extracellular polysaccharides (epss) which may function as virulence factors in diseases caused by these bacteria. the eps levan is synthesized by the extracellular enzyme levansucrase in pseudomonas syringae, erwinia amylovora, and other bacterial species. the lsc genes encoding levansucrase from p. syringae pv. glycinea pg4180 and p. syringae pv. phaseolicola ncppb 1321 were cloned, and their nucleotide sequences were determined. heterologous expressio ... | 1998 | 9726857 |
| expression of the virulence plasmid-carried apyrase gene (apy) of enteroinvasive escherichia coli and shigella flexneri is under the control of h-ns and the virf and virb regulatory cascade. | the transcription of the virulence plasmid (pinv)-carried invasion genes of shigella flexneri and enteroinvasive escherichia coli (eiec) is induced at 37 degreesc and repressed at 30 degreesc. in this work, we report that the o135: k-:h- eiec strain hn280 and s. flexneri sfzm53, m90t, and 454, of serotypes 4, 5, and 2a, respectively, produce apyrase (atp-diphosphohydrolase), the product of the apy gene. in addition, the s. flexneri strains, but not the eiec strain, produce a nonspecific phosphat ... | 1998 | 9746603 |
| lactone-ring-cleaving enzyme: genetic analysis, novel rna editing, and evolutionary implications. | a lactonohydrolase from fusarium oxysporum aku 3702 is an enzyme catalyzing the hydrolysis of aldonate lactones to the corresponding aldonic acids. the amino acid sequences of the nh2 terminus and internal peptide fragments of the enzyme were determined to prepare synthetic oligonucleotides as primers for the pcr. an approximate 1, 000-base genomic dna fragment thus amplified was used as the probe to clone both genomic dna and cdna for the enzyme. the lactonohydrolase genomic gene consists of si ... | 1998 | 9788992 |