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improvement of a nisin-inducible expression vector for use in lactic acid bacteria.the plasmid pmsp3535 is a popular vector for nisin-inducible expression of heterologous genes in lactic acid bacteria. however, the maximum protein expression level achievable with pmsp3535 is relatively low. in an effort to increase expression we modified pmsp3535 to create a high expression variant termed pmsp3535h2. modifications included removal of a small nisa peptide fragment from the p nisa promoter and addition of a bidirectional transcription terminator. in addition the plasmid copy num ...200717624430
engineering the active center of the 6-phospho-beta-galactosidase from lactococcus lactis.several amino acids in the active center of the 6-phospho-beta-galactosidase from lactococcus lactis were replaced by the corresponding residues in homologous enzymes of glycosidase family 1 with different specificities. three mutants, w429a, k435v/y437f and s428d/ k435v/y437f, were constructed. w429a was found to have an improved specificity for glucosides compared with the wild-type, consistent with the theory that the amino acid at this position is relevant for the distinction between galacto ...200010906347
identification of lactic acid bacteria within the consortium of a kefir grain by sequencing 16s rdna variable regions.the microflora of a kefir grain was identified using a polymerase chain reaction-based strategy combined with 16s rrna gene sequencing. dna was extracted from the kefir grain and amplified in its 16s rdna v1 and v2 regions. to guarantee a good representation of the overall lactic acid bacteria populations, dna amplification was performed separately with primers specific either to the dominant or to the less abundant bacterial groups. the amplified fragments were cloned in escherichia coli and th ...200717760349
nisin biosynthesis in vitro.the lantibiotic nisin is produced by lactococcus lactis. in the biosynthesis of nisin, the enzyme nisb dehydrates nisin precursor, and the enzyme nisc is needed for lanthionine formation. in this study, the nisa gene encoding the nisin precursor, and the genes nisb and nisc of the lantibiotic modification machinery were expressed together in vitro by the rapid translation system (rts). analysis of the rts mixture showed that fully modified nisin precursor was formed. by treating the mixture with ...200717827976
on the energy-dependence of hoechst 33342 transport by the abc transporter lmra.lmra is an atp-binding cassette (abc) multidrug transporter from lactococcus lactis, and is a structural homologue of the human multidrug resistance p-glycoprotein (abcb1), the overexpression of which is associated with multidrug resistance in tumours. we recently observed that a truncated version of lmra lacking the nucleotide-binding domain mediates a proton motive force-dependent ethidium transport reaction by catalyzing proton-ethidium symport. this finding raised the question whether proton ...200818061142
evidence for horizontal transfer of ssudat1i restriction-modification genes to the streptococcus suis genome.different strains of streptococcus suis serotypes 1 and 2 isolated from pigs either contained a restriction-modification (r-m) system or lacked it. the r-m system was an isoschizomer of streptococcus pneumoniae dpnii, which recognizes nucleotide sequence 5'-gatc-3'. the nucleotide sequencing of the genes encoding the r-m system in s. suis dat1, designated ssudat1i, showed that the ssudat1i gene region contained two methyltransferase genes, designated ssuma and ssumb, as does the dpnii system. th ...200111133943
bidirectional cell-surface anchoring function of c-terminal repeat region of peptidoglycan hydrolase of lactococcus lactis il1403.with the aim of constructing an efficient protein display system for lactic acid bacteria (labs), the effect of fusion direction on the cell-surface binding activity of the c-terminal region of the peptidoglycan hydrolase (cph) of lactococcus lactis il1403 was studied. cph fused to the alpha-amylase (amy) of streptococcus bovis 148 either at its c-terminus (cph-amy) or at its n-terminus (amy-cph) was expressed intracellularly in escherichia coli. this domain was able to direct binding of amy to ...200818343337
expression of c-terminal repeat region of peptidoglycan hydrolase of lactococcus lactis il1403 in methylotrophic yeast pichia pastoris.the c-terminal region of the peptidoglycan hydrolase (cph) of lactococcus lactis il1403 produced intracellularly in escherichia coli was able to attach to the surface of cells of lactobacillus casei nrrl b-441, bacillus subtilis 168, e. coli xl1-blue and saccharomyces cerevisiae ifo0216. therefore, this domain is a suitable fusion partner for the adhesion of proteins to cell surfaces. the production of cell-surface adhesive proteins using this domain in pichia pastoris is particularly attractive ...200818343340
expression of the capsid protein of porcine circovirus type 2 in lactococcus lactis for oral vaccination.diseases associated with porcine circovirus type 2 (pcv2) infections are becoming a major problem for the swine industry worldwide. the capsid protein (cap) of pcv2 is an antigen important for both early diagnosis and development of vaccines. in this study, lactococcus lactis was used as vehicle to deliver the pcv2 antigen in an attempt to develop oral vaccine. a cap gene with a deleted nuclear localization signal sequence (dcap) was cloned into an escherichia coli/l. lactis shuttle vector psec: ...200818406475
the lactococcus lactis fabf fatty acid synthetic enzyme can functionally replace both the fabb and fabf proteins of escherichia coli and the fabh protein of lactococcus lactis.the genome of lactococcus lactis encodes a single long chain 3-ketoacyl-acyl carrier protein synthase. this is in contrast to its close relative, enterococcus faecalis, and to escherichia coli, both of which have two such enzymes. in e. faecalis and e. coli, one of the two long chain synthases (fabo and fabb, respectively) has a role in unsaturated fatty acid synthesis that cannot be satisfied by fabf, the other long chain synthase. since l. lactis has only a single long chain 3-ketoacyl-acyl ca ...200818523755
molecular characterization of a clostridium difficile bacteriophage and its cloned biologically active endolysin.clostridium difficile infection is increasing in both frequency and severity, with the emergence of new highly virulent strains highlighting the need for more rapid and effective methods of control. here, we show that bacteriophage endolysin can be used to inhibit and kill c. difficile. the genome sequence of a novel bacteriophage that is active against c. difficile was determined, and the bacteriophage endolysin gene was subcloned and expressed in escherichia coli. the partially purified endoly ...200818708505
introduction of an nadh regeneration system into klebsiella oxytoca leads to an enhanced oxidative and reductive metabolism of glycerol.redox cofactors play crucial roles in the metabolic and regulatory network of living organisms. we reported here the effect of introducing a heterogeneous nadh regeneration system into klebsiella oxytoca on cell growth and glycerol metabolism. expression of fdh gene from candida boidinii in k. oxytoca resulted in higher intracellular concentrations of both nadh and nad(+) during the fermentation metaphase, with the ratio of nadh to nad(+) unaltered and cell growth unaffected, interestingly diffe ...200919100856
eci5, a group iib intron with high retrohoming frequency: dna target site recognition and use in gene targeting.we find that group ii intron eci5, a subclass cl/iib1 intron from an escherichia coli virulence plasmid, is highly active in retrohoming in e. coli. both full-length eci5 and an eci5-deltaorf intron with the intron-encoded protein expressed separately from the same donor plasmid retrohome into a recipient plasmid target site at substantially higher frequencies than do similarly configured lactococcus lactis ll.ltrb introns. a comprehensive view of dna target site recognition by eci5 was obtained ...200919155322
lipid-mediated light activation of a mechanosensitive channel of large conductance.this paper describes the reversible activation of a mechanosensitive channel via a light-sensitive lipid mimic. for these experiments, the mechanosensitive channel of large conductance (mscl) protein from lactococcus lactis and escherichia coli was reconstituted in lipid bilayers composed of 80 mol % 1,2-dioleoyl-sn-glycero-3-phosphocholine and 20 mol % di-(5-[[4-(4-butylphenyl)azo]phenoxy]pentyl)phosphate (4-azo-5p). light-induced isomerization of the azobenzene moiety of 4-azo-5p from trans to ...200415301476
large increase in brazzein expression achieved by changing the plasmid /strain combination of the nice system in lactococcus lactis.to evaluate brazzein production in lactococcus lactis using the nisin-controlled expression (nice) system. the approach is through analysis of different plasmid/strain combinations.200919413801
inhibition of uropathogens by lactic acid bacteria isolated from dairy foods and cow's intestine in western nigeria.a total of 96 lactic acid bacteria (lab) were isolated from african indigenous fermented products and cow's intestines to study their inhibitory capability against multi-drug-resistant uropathogens. escherichia coli accounted for approximately 45% of isolated uropathogens, followed by staphylococcus spp. (20%). the gram negative uropathogens were highly resistant to quinolones, co-trimoxazole, teicoplanin and some beta-lactams, while the staphylococcus spp. showed high resistance to aminoglycosi ...200919529917
membrane topology of the sodium ion-dependent citrate carrier of klebsiella pneumoniae. evidence for a new structural class of secondary transporters.the predicted secondary structure model of the sodium ion-dependent citrate carrier of klebsiella pneumoniae (cits) presents the 12-transmembrane helix motif observed for many secondary transporters. biochemical evidence presented in this paper is not consistent with this model. n-terminal and c-terminal fusions of cits with the biotin acceptor domain of the oxaloacetate decarboxylase of k. pneumoniae catalyze citrate transport, showing the correct folding of the cits part of the fusion proteins ...19968810332
intra- and interspecies conjugal transfer of tn916-like elements from lactococcus lactis in vitro and in vivo.tetracycline-resistant lactococcus lactis strains originally isolated from polish raw milk were analyzed for the ability to transfer their antibiotic resistance genes in vitro, using filter mating experiments, and in vivo, using germfree rats. four of six analyzed l. lactis isolates were able to transfer tetracycline resistance determinants in vitro to l. lactis bu2-60, at frequencies ranging from 10(-5) to 10(-7) transconjugants per recipient. three of these four strains could also transfer res ...200919666731
functional features of an ssi signal of plasmid pgkv21 in escherichia coli.a single-strand initiation (ssi) signal was detected on the lactococcus lactis plasmid pgkv21 containing the replicon of pwv01 by its ability to complement the poor growth of an m13 phage derivative (m13 delta lac182) lacking the complementary-strand origin in escherichia coli. this ssi signal was situated at the 229-nucleotide (nt) ddei-drai fragment and located within the 109 nt upstream of the nick site of the putative plus origin. ssi activity is orientation specific with respect to the dire ...19979294437
oral administration of lactococcus lactis expressing helicobacter pylori cag7-ct383 protein induces systemic anti-cag7 immune response in mice.to express the 3'-region (1152 bp) of the cag7 gene of helicobacter pylori 51 strain, encoding the c-terminal 383 amino acid (ct383 aa) region of cag7 protein that is known to cover the needle region of t4ss, in a live delivery vehicle lactococcus lactis, the cag7-ct383 gene was amplified by pcr. dna sequence analysis revealed that the amino acid sequence of cag7-ct383 of h. pylori 51 shared 98.4% and 97.4% identity with h. pylori 26695 and j99, respectively. intramuscular injection of the gst-c ...200919807786
a bacterial group ii intron encoding reverse transcriptase, maturase, and dna endonuclease activities: biochemical demonstration of maturase activity and insertion of new genetic information within the intron.the lactococcus lactis group ii intron ll.ltrb is similar to mobile yeast mtdna group ii introns, which encode reverse transcriptase, rna maturase, and dna endonuclease activities for site-specific dna insertion. here, we show that the lactococcal intron can be expressed and spliced efficiently in escherichia coli. the intron-encoded protein ltra has reverse transcriptase and rna maturase activities, with the latter activity shown both in vivo and in vitro, a first for any group ii intron-encode ...19979353259
genes involved in immunity to the lantibiotic nisin produced by lactococcus lactis 6f3.the lantibiotic nisin is produced by several strains of lactococcus lactis. the complete gene cluster for nisin biosynthesis in l. lactis 6f3 comprises 15 kb of dna. as described previously, the structural gene nisa is followed by the genes nisb, nist, nisc, nisi, nisp, nisr, and nisk. further analysis revealed three additional open reading frames, nisf, nise, and nisg, adjacent to nisk. approximately 1 kb downstream of the nisg gene, three open reading frames in the opposite orientation have be ...19957793910
origin of the putrescine-producing ability of the coagulase-negative bacterium staphylococcus epidermidis 2015b.a multiplex pcr method, aimed at the detection of genes associated with biogenic amine production, identified the odc gene encoding ornithine decarboxylase in 1 of 15 strains of staphylococcus epidermidis. the ability of the positive strain, s. epidermidis 2015b, to produce putrescine in vitro was demonstrated by high-performance liquid chromatography (hplc). in this strain, the odc gene was detected on plasmid dna, suggesting that the ability to form putrescine is carried by a mobile element, w ...201020581187
metabolic engineering of escherichia coli for the production of succinate from glycerol.glycerol has become an ideal feedstock for the microbial production of bio-based chemicals due to its abundance, low cost, and high degree of reduction. we have previously reported the pathways and mechanisms for the utilization of glycerol by escherichia coli in minimal salts medium under microaerobic conditions. here we capitalize on such results to engineer e. coli for the production of value-added succinate from glycerol. through metabolic engineering of e. coli metabolism, succinate product ...201020601068
radiosensitization of hypoxic bacterial cells by nitroimidazoles of low lipophilicity: steady-state and rapid-mix studies. 19816782616
secretory expression of k88 (f4) fimbrial adhesin faeg by recombinant lactococcus lactis for oral vaccination and its protective immune response in mice.k88 (f4) fimbrial adhesin, faeg, was expressed extracellularly in lactococcus lactis using a nisin-controlled gene expression system. the antibody response and protective efficacy of the recombinant bacteria (l. lactis [spnz8048-faeg]) against live enterotoxigenic e. coli (etec) c(83549) challenge were evaluated in icr mice. mice vaccinated with l. lactis [spnz8048-faeg] had a significantly increased antigen-specific igg level in the serum and decreased mortality rate (p < 0.05) compared with th ...200919277476
screening for antimicrobial resistance genes and virulence factors via genome sequencing.second-generation genome sequencing and alignment of the resulting reads to in silico genomes containing antimicrobial resistance and virulence factor genes were used to screen for undesirable genes in 28 strains which could be used in human nutrition. no virulence factor genes were detected, while several isolates contained antimicrobial resistance genes.201121335393
short communication: characterization of microflora in mexican chihuahua cheese.this work was performed to identify the bacterial species present in 10 chihuahua cheeses obtained from commercial producers in mexico using 16s rrna gene analysis. as expected, some of the agar media initially used for isolation were not very selective, supporting the growth of several unrelated bacterial species. sequence analysis identified potential pathogens, including escherichia coli and staphylococcus aureus, in all raw milk samples and 2 pasteurized milk samples. streptococcus thermophi ...201121700016
molecular and genetic characterization of lactose-metabolic genes of streptococcus cremoris.lac+ plasmid dna from streptococcus cremoris h2 was subcloned with an escherichia coli vector on a 3.5-kilobase-pair psti-avai fragment. genetic analysis of the cloned dna was possible because linear lac+ dna fragments were productive in the s. sanguis transformation system. complementation of s. sanguis lac-mutants showed that the 3.5-kilobase-pair fragment included the structural gene for 6-phospho-beta-d-galactosidase and either enzyme ii-lac or factor iii-lac of the lactose-specific phosphoe ...19863091581
construction of theta-type shuttle vector for leuconostoc and other lactic acid bacteria using pcb42 isolated from kimchi.the pcb42 plasmid from leuconostoc citreum cb2567, a strain isolated from kimchi, was characterized, and a shuttle vector for escherichia coli and lactic acid bacteria (lab) was constructed. the pcb42 plasmid has a circular structure of 4312bp, a low g+c content, and no single-stranded dna intermediates during replication, which indicates that pcb42 replicates via the theta-type replication mechanism. in silico analysis of this plasmid revealed 6 open reading frames: 1 transposase gene, 1 dna-bi ...201222133745
identical transcriptional control of the divergently transcribed prtp and prtm genes that are required for proteinase production in lactococcus lactis sk11.we have investigated transcriptional regulation of the divergently transcribed genes required for proteinase production (prtp and prtm) of lactococcus lactis sk11. their promoters partially overlap and are arranged in a face-to-face configuration. the medium-dependent activities of both prtp and prtm promoters were analyzed by quantitative primer extension studies and beta-glucuronidase assays with l. lactis mg1363 cells harboring transcriptional gene fusions of each promoter with the promoterle ...19968626277
a novel plasmid for delivering genes into mammalian cells with noninvasive food and commensal lactic acid bacteria.using food and commensal lactic acid bacteria (lab) as vehicles for dna delivery into epithelial cells is a new strategy for vaccine delivery or gene therapy. however, present methods for dna delivery with lab have suffered low efficiency. our goal was to develop a new system to deliver dna into epithelial cells with high efficiency using food and commensal lab. an escherichia coli-lab shuttle plasmid, plkv1, for dna delivery into eukaryotic cells was constructed. two reporter plasmids with gree ...201120832422
restriction for gene insertion within the lactococcus lactis ll.ltrb group ii intron.the ll.ltrb intron, from the low g+c gram-positive bacterium lactococcus lactis, was the first bacterial group ii intron shown to splice and mobilize in vivo. the detailed retrohoming and retrotransposition pathways of ll.ltrb were studied in both l. lactis and escherichia coli. this bacterial retroelement has many features that would make it a good gene delivery vector. here we report that the mobility efficiency of ll.ltrb expressing ltra in trans is only slightly affected by the insertion of ...200616973892
expression of clpx, an atpase subunit of the clp protease, is heat and cold shock inducible in lactococcus lactis.in this study, the clpx gene and surrounding sequences were cloned and sequenced from lactococcus lactis. the putative clpx gene encodes a 411 amino acid polypeptide with a predicted molecular weight of 45.8 kda. analysis of the relative levels of clpx transcript revealed that in addition to a role in proteolysis of heat damaged proteins, clpx may also be involved in cryoprotection.200111518300
possible promoter regions within the proteolytic system in streptococcus thermophilus and their interaction with the cody homolog.possible promoter regions preceding 14 genes belonging to the proteolytic system of streptococcus thermophilus klds 3.0503 were predicted by a promoter analysis software nnpp. the 14 genes included an extracellular protease gene prts, an oligopeptide abc transport system gene amia1, and 12 genes, respectively, encoding peptidases pepa, peps, pepn, pepc, pepb, pepq, pepv, pept, pepm, pepxp, pepp, and pepo. these predicted promoter sequences were cloned and inserted into the upstream of a promoter ...200919552712
ferrihydrite reduction by geobacter species is stimulated by secondary bacteria.geobacter species such as g. bremensis, g. pelophilus, and g. sulfurreducens are obligately anaerobic and grow in anoxic, non-reduced medium by fast reduction of soluble ferric citrate. in contrast, insoluble ferrihydrite was either only slowly or not reduced when supplied as electron acceptor in similar growth experiments. ferrihydrite reduction was stimulated by addition of a reducing agent or by concomitant growth of secondary bacteria that were physiologically and phylogenetically as diverse ...200415340790
universal method for synthesis of artificial gel antibodies by the imprinting approach combined with a unique electrophoresis technique for detection of minute structural differences of proteins, viruses, and cells (bacteria). iii: gel antibodies against cells (bacteria).artificial antibodies in the form of gel granules were synthesized from the monomers acrylamide and n,n'-methylenebisacrylamide by the imprinting method in the presence of echerichia coli bacteria as template. the electrophoretic migration velocities of the gel antibodies (i) saturated with the antigen (escherichia coli mre-600), (ii) freed of the antigen, and (iii) resaturated with bacteria, were determinated by electrophoresis in a rotating narrow-bore tube of 245 mm length and the 2.5 and 9.6 ...200617136716
the unconventional xer recombination machinery of streptococci/lactococci.homologous recombination between circular sister chromosomes during dna replication in bacteria can generate chromosome dimers that must be resolved into monomers prior to cell division. in escherichia coli, dimer resolution is achieved by site-specific recombination, xer recombination, involving two paralogous tyrosine recombinases, xerc and xerd, and a 28-bp recombination site (dif) located at the junction of the two replication arms. xer recombination is tightly controlled by the septal prote ...200717630835
the ribonucleotide reductase system of lactococcus lactis. characterization of an nrdef enzyme and a new electron transport protein.escherichia coli contains the genetic information for three separate ribonucleotide reductases. two of them (class i enzymes), coded by the nrdab and nrdef genes, respectively, contain a tyrosyl radical, whose generation requires oxygen. the nrdab enzyme is physiologically active. the function of the nrdef gene is not known. the third enzyme (class iii), coded by nrddg, operates during anaerobiosis. the dna of lactococcus lactis contains sequences homologous to the nrddg genes. surprisingly, an ...19968621514
using lactococcus lactis for glutathione overproduction.glutathione and gamma-glutamylcysteine were produced in lactococcus lactis using a controlled expression system and the genes gsha and gshb from escherichia coli encoding the enzymes gamma-glutamylcysteine synthetase and glutathione synthetase. high levels of gamma-glutamylcysteine were found in strains growing on chemically defined medium and expressing either gsha alone or both gsha and gshb. as anticipated, glutathione was found in a strain expressing gsha and gshb. the level of glutathione p ...200515490155
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 ...19989435063
a nudix enzyme removes pyrophosphate from dihydroneopterin triphosphate in the folate synthesis pathway of bacteria and plants.removal of pyrophosphate from dihydroneopterin triphosphate (dhntp) is the second step in the pterin branch of the folate synthesis pathway. there has been controversy over whether this reaction requires a specific pyrophosphohydrolase or is a metal ion-dependent chemical process. the genome of lactococcus lactis has a multicistronic folate synthesis operon that includes an open reading frame (ylgg) specifying a putative nudix hydrolase. because many nudix enzymes are pyrophosphohydrolases, ylgg ...200415611104
steady-state kinetics of the glutaminase reaction of ctp synthase from lactococcus lactis. the role of the allosteric activator gtp incoupling between glutamine hydrolysis and ctp synthesis.ctp synthase catalyzes the reaction glutamine + utp + atp --> glutamate + ctp + adp + pi. the rate of the reaction is greatly enhanced by the allosteric activator gtp. we have studied the glutaminase half-reaction of ctp synthase from lactococcus lactis and its response to the allosteric activator gtp and nucleotides that bind to the active site. in contrast to what has been found for the escherichia coli enzyme, gtp activation of the l. lactis enzyme did not result in similar kcat values for th ...200212354108
restrictive use of detergents in the functional reconstitution of the secondary multidrug transporter lmrp.the histidine-tagged secondary multidrug transporter lmrp was overexpressed in lactococcus lactis, using a novel protein expression system for cytotoxic proteins based on the tightly regulated, nisin-inducible nisa promoter. lmrp-mediated h+/drug antiport activity in inside-out membrane vesicles was inhibited by detergents, such as triton x-100, triton x-114, and tween 80, at low concentrations that did not affect the magnitude or composition of the proton motive force. the inhibition of the act ...19999893996
molecular properties of the glucosaminidase acma from lactococcus lactis mg1363: mutational and biochemical analyses.the major autolysin acma of lactococcus lactis ssp. cremoris mg1363 is a modular protein consisting of an n-terminal signal sequence, a central enzymatic region (glu(acma) as a glucosaminidase), and a c-terminal cell-recognition domain (lysm123). glu(acma) (about 160 amino acids) belongs to the glycoside hydrolase (gh) 73 family, and the two acidic residues e128 and d153 have been thought to be catalytically important. in this study, amino-acid substitution analysis of acma was first carried out ...200919686822
structure of the branched-chain keto acid decarboxylase (kdca) from lactococcus lactis provides insights into the structural basis for the chemoselective and enantioselective carboligation reaction.the thiamin diphosphate (thdp) dependent branched-chain keto acid decarboxylase (kdca) from lactococcus lactis catalyzes the decarboxylation of 3-methyl-2-oxobutanoic acid to 3-methylpropanal (isobutyraldehyde) and co2. the enzyme is also able to catalyze carboligation reactions with an exceptionally broad substrate range, a feature that makes kdca a potentially valuable biocatalyst for c-c bond formation, in particular for the enzymatic synthesis of diversely substituted 2-hydroxyketones with h ...200718084069
characterization, expression, and mutation of the lactococcus lactis galpmkte genes, involved in galactose utilization via the leloir pathway.a cluster containing five similarly oriented genes involved in the metabolism of galactose via the leloir pathway in lactococcus lactis subsp. cremoris mg1363 was cloned and characterized. the order of the genes is galpmkte, and these genes encode a galactose permease (galp), an aldose 1-epimerase (galm), a galactokinase (galk), a hexose-1-phosphate uridylyltransferase (galt), and a udp-glucose 4-epimerase (gale), respectively. this genetic organization reflects the order of the metabolic conver ...200312533462
lex marks the spot: the virulent side of sos and a closer look at the lexa regulon.the sos response that responds to dna damage induces many genes that are under lexa repression. a detailed examination of lexa regulons using genome-wide techniques has recently been undertaken in both escherichia coli and bacillus subtilis. these extensive and elegant studies have now charted the extent of the lexa regulons, uncovered many new genes, and exposed a limited overlap in the lexa regulon between the two bacteria. as more bacterial genomes are analysed, more curiosities in lexa regul ...200617042786
immune responses elicited in mice with recombinant lactococcus lactis expressing f4 fimbrial adhesin faeg by oral immunization.enterotoxigenic escherichia coli (etec) is a major pathogenic agent causing piglet diarrhea. the major subunit and adhesin faeg of f4(+) etec is an important virulence factor with strong immunogenicity. to determine whether lactococcus lactis (l. lactis) could effectively deliver faeg to the mucosal immune system, recombinant l. lactis expressing faeg was constructed, and immune responses in mice following oral route delivery of recombinant l. lactis were explored. the production of faeg express ...201020532816
effect of sorghum vulgare phosphoenolpyruvate carboxylase and lactococcus lactis pyruvate carboxylase coexpression on succinate production in mutant strains of escherichia coli.sorghum vulgare phosphoenolpyruvate carboxylase (pepc) and lactococcus lactis pyruvate carboxylase (pyc) were overexpressed in escherichia coli concurrently to improve the production of succinate, a valuable industrial specialty chemical. this coexpression system was also applied to e. coli mutant strains strategically designed by inactivating the competing pathways of succinate formation. the highest level of succinate production was observed in e. coli strains coexpressing both pepc and pyc wh ...200515565333
the anaerobic (class iii) ribonucleotide reductase from lactococcus lactis. catalytic properties and allosteric regulation of the pure enzyme system.lactococcus lactis contains an operon with the genes (nrdd and nrdg) for a class iii ribonucleotide reductase. strict anaerobic growth depends on the activity of these genes. both were sequenced, cloned, and overproduced in escherichia coli. the corresponding proteins, nrdd and nrdg, were purified close to homogeneity. the amino acid sequences of nrdd (747 residues, 84.1 kda) and nrdg (199 residues, 23.3 kda) are 53 and 42% identical with the respective e. coli proteins. together, they catalyze ...200010644700
expression of espa in lactococcus lactis nz9000 and the detection of its immune effect in vivo and vitro.enterhemorrhagic escherichia coli (epec), an important cause of severe infantile diarrheal disease in many parts of the developing world, produced several recently described virulence determinations. several of its virulence factors are secreted by type iii secretion including espa, which forms filamentous structures on bacterial surface bridging to the host cell's surface. these structures on bacterial surfaces may deliver other virulence factors directly into the host cell from ehec. in this s ...201020001787
uplc/ms based method for quantitative determination of fatty acid composition in gram-negative and gram-positive bacteria.quantitative fatty acid composition of microorganisms at various growth space points is required for understanding membrane associated processes of cells, but the majority of the relevant publications still restrict to the relative compositions. in the current study, a simple and reliable method for quantitative measurement of fatty acid content in bacterial biomass without prior derivatization using ultra performance liquid chromatography-electrospray ionization mass spectrometry was developed. ...201020621131
biosynthesis of polyhydroxyalkanoates containing 2-hydroxybutyrate from unrelated carbon source by metabolically engineered escherichia coli.we have previously reported in vivo biosynthesis of polylactic acid (pla) and poly(3-hydroxybutyrate-co-lactate) [p(3hb-co-la)] employing metabolically engineered escherichia coli strains by the introduction of evolved clostridium propionicum propionyl-coa transferase (pct( cp )) and pseudomonas sp. mbel 6-19 polyhydroxyalkanoate (pha) synthase 1 (phac1( ps6-19)). using this in vivo pla biosynthesis system, we presently report the biosynthesis of phas containing 2-hydroxybutyrate (2hb) monomer b ...201121842437
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