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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
expression, purification, and characterization of arginine deiminase from lactococcus lactis ssp. lactis atcc 7962 in escherichia coli bl21.the arca gene that encodes arginine deiminase (adi, ec 3.5.3.6)--a key enzyme of the adi pathway--was cloned from lactococcus lactis ssp. lactis atcc 7962. the deduced amino acid sequence of the arca gene showed high homology with the arca gene from lactobacillus plantarum (99%) and from lactobacillus sakei (60%), respectively. the arca gene from lc. lactis spp. lactis atcc 7962 was expressed in soluble fraction of recombinant escherichia coli bl21. adi produced from lc. lactis spp. lactis atcc ...200717223359
genotypic and phenotypic diversity of lactococcus lactis isolates from batzos, a greek pdo raw goat milk cheese.the genotypic and phenotypic variability of 40 lactococcus lactis isolates obtained from three cheese-making trials of batzos cheese made one in each, winter, spring and summer was investigated. rapd-pcr, plasmid profiling and pfge were used to study the genetic variability and distinguish closely related isolates. results showed a high degree of heterogeneity among strains. according to pfge data, all strains except one were clustered together (at a similarity level of approximately 50%) with t ...200717241681
characterization of the lactococcal group ii intron target site in its native host.the lactococcus lactis group ii intron (ll.ltrb) retrohomes into the ltrb gene at high efficiency. to date, the critical dna bases recognized in vivo by the ll.ltrb ribonucleoprotein (rnp) have been exclusively elucidated in escherichia coli. however, recent evidence indicates host-dependant differences in ll.ltrb mobility, raising the possibility of limitations of the current model for rnp-homing site recognition in the native l. lactis host. in this work, intron retargeting experiments in l. l ...200717408740
in vivo functional analyses of the type ii acyl carrier proteins of fatty acid biosynthesis.acyl carrier protein (acp) is a key component of the fatty acid synthesis pathways of both type i and type ii synthesis systems. a large number of structure-function studies of various type ii acps have been reported, but all are in vitro studies that assayed function or interaction of mutant acps with various enzymes of fatty acid synthesis or transfer. hence in these studies functional properties of various mutant acps were assayed with only a subset of the many acp-interacting proteins, which ...200717522044
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
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
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
antimicrobial properties of lactic acid bacteria and yeast-lab cultures isolated from traditional fermented milk against pathogenic escherichia coli and salmonella enteritidis strains.the survival and growth of escherichia coli 3339 and salmonella enteritidis 949575 isolated from human clinical samples, in milk fermented with lactic acid bacteria (lab) and yeast strains previously isolated from zimbabwean naturally fermented milk (nfm) was studied. the lab starter cultures used were lactococcus lactis subsp. lactis biovar. diacetylactis c1 alone (c1) or in combination with candida kefyr 23 (c1/23), l. lactis subsp. lactis lc261 alone (lc261) or in combination with c. kefyr 23 ...200616387379
expression of helicobacter pylori cag12 gene in lactococcus lactis mg1363 and its oral administration to induce systemic anti-cag12 immune response in mice.to develop an oral vaccine against helicobacter pylori infection, we have expressed the h. pylori cag12 (hp0532) gene, encoding the outer membrane protein cag12 (31 kda), in a live delivery vehicle lactococcus lactis. the cag12 gene was amplified by polymerase chain reaction (pcr) using the genomic dna of h. pylori k51 isolated from korean patients. dna sequence analysis revealed that the cag12 gene of h. pylori k51 has 98.1 and 97.4% identity with individual cag12 genes of the h. pylori 26695 a ...200616586107
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
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
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
human lysozyme expressed in the mammary gland of transgenic dairy goats can inhibit the growth of bacteria that cause mastitis and the cold-spoilage of milk.the addition of human milk components with intrinsic antimicrobial activity to livestock milk by genetic engineering has the potential to benefit milk safety and production as well as the health of the lactating animal. as a model for the dairy cow, we generated transgenic goats that expressed human lysozyme in their milk at 68% of the levels found in human milk. milk from these transgenic animals had a bacteriostatic effect on both in vitro and in vivo growth of several microorganisms important ...200617199520
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
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
combined effect of high-pressure treatments and bacteriocin-producing lactic acid bacteria on inactivation of escherichia coli o157:h7 in raw-milk cheese.the effect of high-pressure (hp) treatments combined with bacteriocins of lactic acid bacteria (lab) produced in situ on the survival of escherichia coli o157:h7 in cheese was investigated. cheeses were manufactured from raw milk inoculated with e. coli o157:h7 at approximately 10(5) cfu/ml. seven different bacteriocin-producing lab were added at approximately 10(6) cfu/ml as adjuncts to the starter. cheeses were pressurized on day 2 or 50 at 300 mpa for 10 min or 500 mpa for 5 min, at 10 degree ...200516000741
transcriptional analysis of the cyclopropane fatty acid synthase gene of lactococcus lactis mg1363 at low ph.cyclopropane fatty acid synthase (cfa) catalyses the transfer of a methyl group from s-adenosylmethionine (sam) to unsaturated fatty acids. northern blot experiments demonstrated that the lactococcus lactis mg1363 cfa gene is mainly expressed as a bicistronic transcript together with metk, the gene encoding sam synthetase, and is highly induced by acidity. the cfa promoter was characterized by 5'-race pcr, and fused to beta-galactosidase by cloning into the pak80 plasmid. this transcriptional fu ...200516098686
molecular analysis of colonized bacteria in a human newborn infant gut.the complex ecosystem of intestinal microflora is estimated to harbor approximately 400 different microbial species, mostly bacteria. however, studies on bacterial colonization have mostly been based on culturing methods, which only detect a small fraction of the whole microbiotic ecosystem of the gut. to clarify the initial acquisition and subsequent colonization of bacteria in an infant within the few days after birth, phylogenetic analysis was performed using 16s rdna sequences from the dna i ...200516145549
drug-lipid a interactions on the escherichia coli abc transporter msba.msba is an essential atp-binding cassette half-transporter in the cytoplasmic membrane of the gram-negative escherichia coli and is required for the export of lipopolysaccharides (lps) to the outer membrane, most likely by transporting the lipid a core moiety. consistent with the homology of msba to the multidrug transporter lmra in the gram-positive lactococcus lactis, our recent work in e. coli suggested that msba might interact with multiple drugs. to enable a more detailed analysis of multid ...200516159769
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
function of prokaryotic and eukaryotic abc proteins in lipid transport.atp binding cassette (abc) proteins of both eukaryotic and prokaryotic origins are implicated in the transport of lipids. in humans, members of the abc protein families a, b, c, d and g are mutated in a number of lipid transport and metabolism disorders, such as tangier disease, stargardt syndrome, progressive familial intrahepatic cholestasis, pseudoxanthoma elasticum, adrenoleukodystrophy or sitosterolemia. studies employing transfection, overexpression, reconstitution, deletion and inhibition ...200415749056
attenuation regulation of amino acid biosynthetic operons in proteobacteria: comparative genomics analysis.candidate attenuators were identified that regulate operons responsible for biosynthesis of branched amino acids, histidine, threonine, tryptophan, and phenylalanine in gamma- and alpha-proteobacteria, and in some cases in low-gc gram-positive bacteria, thermotogales and bacteroidetes/chlorobi. this allowed us not only to describe the evolutionary dynamics of regulation by attenuation of transcription, but also to annotate a number of hypothetical genes. in particular, orthologs of ygea of esche ...200415135544
antimicrobial potential of immobilized lactococcus lactis subsp. lactis atcc 11454 against selected bacteria.immobilization of living cells of lactic acid bacteria could be an alternative or complementary method of immobilizing organic acids and bacteriocins and inhibit undesirable bacteria in foods. this study evaluated the inhibition potential of immobilized lactococcus lactis subsp. lactis atcc 11454 on selected bacteria by a modified method of the agar spot test. l. lactis was immobilized in calcium alginate (1 to 2%)-whey protein concentrate (0 and 1%) beads. the antimicrobial potential of immobil ...200415222547
high-level gene expression in lactobacillus plantarum using a pheromone-regulated bacteriocin promoter.to use promoters and regulatory genes involved in the production of the bacteriocin sakacin p to obtain high-level regulated gene expression in lactobacillus plantarum.200415242451
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
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
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
engineering lactic acid bacteria with pyruvate decarboxylase and alcohol dehydrogenase genes for ethanol production from zymomonas mobilis.lactic acid bacteria are candidates for engineered production of ethanol from biomass because they are food-grade microorganisms that can, in many cases, metabolize a variety of sugars and grow under harsh conditions. in an effort to divert fermentation from production of lactic acid to ethanol, plasmids were constructed to express pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adh), encoded by the pdc and adhb genes of zymomonas mobilis, in lactic acid bacteria. several strains were tr ...200312750944
the atp binding cassette multidrug transporter lmra and lipid transporter msba have overlapping substrate specificities.lmra is an atp binding cassette (abc) multidrug transporter in lactococcus lactis that is a structural and functional homologue of the human multidrug resistance p-glycoprotein mdr1 (abcb1). lmra is also homologous to msba, an essential abc transporter in escherichia coli involved in the trafficking of lipids, including lipid a. we have compared the substrate specificities of lmra and msba in detail. surprisingly, lmra was able to functionally substitute for a temperature-sensitive mutant msba i ...200312842882
characterization of the llaci methyltransferase from lactococcus lactis subsp. cremoris w15 provides new insights into the biology of type ii restriction-modification systems.the gene encoding the llaci methyltransferase (m.llaci) from lactococcus lactis subsp. cremoris w15 was overexpressed in escherichia coli. the enzyme was purified to apparent homogeneity using three consecutive steps of chromatography on phosphocellulose, blue-agarose and superose 12hr, yielding a protein of m(r) 31 300+/-1000 under denaturing conditions. the exact position of the start codon aug was determined by protein microsequencing. this enzyme recognizes the specific palindromic sequence ...200314600245
phage tp901-1 site-specific integrase functions in human cells.we demonstrate that the site-specific integrase encoded by phage tp901-1 of lactococcus lactis subsp. cremoris has potential as a tool for engineering mammalian genomes. we constructed vectors that express this integrase in escherichia coli and in mammalian cells and developed a simple plasmid assay to measure the frequency of intramolecular integration mediated by the integrase. we used the assay to document that the integrase functions efficiently in e. coli and determined that for complete re ...200212057961
bacterial multidrug resistance mediated by a homologue of the human multidrug transporter p-glycoprotein.most atp-binding cassette (abc) multidrug transporters known to date are of eukaryotic origin, such as the p-glycoproteins (pgps) and multidrug resistance-associated proteins (mrps). only one well-characterized abc multidrug transporter, lmra, is of bacterial origin. on the basis of its structural and functional characteristics, this bacterial protein is classified as a member of the p-glycoprotein cluster of the abc transporter superfamily. lmra can even substitute for p-glycoprotein in human l ...200212120998
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
cloning vectors for streptococcus thermophilus derived from a native plasmid.a 3.5-kb native plasmid (pnd103) was identified in streptococcus thermophilus st2-1. preliminary sequence analysis indicated that pnd103 belongs to group i s. thermophilus plasmids. a region of approximately 2 kb appears to contain three components: a plus origin of replication (ori) typical of plasmids that replicate via rolling circle replication; a gene encoding a replication protein (rep); and a gene encoding a small heat shock protein (hsp). pnd103 was then used to construct s. thermophilus ...200212423750
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
identification of mur, an atypical peptidoglycan hydrolase derived from leuconostoc citreum.a gene encoding a protein homologous to known bacterial n-acetyl-muramidases has been cloned from leuconostoc citreum by a pcr-based approach. the encoded protein, mur, consists of 209 amino acid residues with a calculated molecular mass of 23,821 da including a 31-amino-acid putative signal peptide. in contrast to most of the other known peptidoglycan hydrolases, l. citreum mur protein does not contain amino acid repeats involved in cell wall binding. the purified l. citreum mur protein was sho ...200111157255
analysis of six prophages in lactococcus lactis il1403: different genetic structure of temperate and virulent phage populations.we report the genetic organisation of six prophages present in the genome of lactococcus lactis il1403. the three larger prophages (36-42 kb), belong to the already described p335 group of temperate phages, whereas the three smaller ones (13-15 kb) are most probably satellites relying on helper phage(s) for multiplication. these data give a new insight into the genetic structure of lactococcal phage populations. p335 temperate phages have variable genomes, sharing homology over only 10-33% of th ...200111160885
bovine rotavirus nonstructural protein 4 produced by lactococcus lactis is antigenic and immunogenic.rotavirus nonstructural protein 4 (nsp4) can induce diarrhea in mice. to get insight into the biological effects of nsp4, production of large quantities of this protein is necessary. we first tried to produce the protein in escherichia coli, but the nsp4 gene proved to be unstable. the capacity of the generally regarded as safe organism lactococcus lactis to produce nsp4 either intra- or extracellularly was then investigated by using the nisin-controlled expression system. production of recombin ...200111282586
genetic evidence for a defective xylan degradation pathway in lactococcus lactis.genetic and biochemical evidence for a defective xylan degradation pathway was found linked to the xylose operon in three lactococcal strains, lactococcus lactis 210, l. lactis io-1, and l. lactis nrrl b-4449. immediately downstream of the xylulose kinase gene (xylb) (k. a. erlandson, j.-h. park, w. el khal, h.-h. kao, p. basaran, s. brydges, and c. a. batt, appl. environ. microbiol. 66:3974-3980, 1999) are two open reading frames encoding a mutarotase (xylm) and a xyloside transporter (xynt) an ...200111282589
nucleotide sequence and characterization of the cell envelope proteinase plasmid in lactococcus lactis subsp. cremoris hp.the major cell envelope proteinase (lactocepin; ec 3.4.21.96) produced by lactococcus lactis cheese starter bacteria is required for starter growth and acid production in milk. the aim of this study was to characterize a lactocepin plasmid from a l. lactis subsp. cremoris cheese starter strain.200111473599
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
phylogenetic analysis of gram-positive bacteria based on grpe, encoded by the dnak operon.the dnak operon in gram-positive bacteria includes grpe, dnaj and, in some members, hrca as well. both dnak and dnaj have been utilized for constructing phylogenetic relationships among various organisms. multiple copies exist for dnak and dnaj genes in some bacterial genera, as opposed to a single gene copy for grpe and for hrca, according to the currently available data. here, we present a partial protein-based phylogenetic tree for gram-positive bacteria, derived by using the amino acid seque ...200011034484
mutational analysis of two structural genes of the temperate lactococcal bacteriophage tp901-1 involved in tail length determination and baseplate assembly.two putative structural genes, orf tmp (tape measure protein) and orf bpp (baseplate protein), of the temperate lactococcal phage tp901-1 were examined by introduction of specific mutations in the prophage strain lactococcus lactic ssp. cremoris 901-1. the adsorption efficiencies of the mutated phages to the indicator strain l. lactic ssp. cremoris 3107 were determined and electron micrographs were obtained. specific mutations in orf tmp resulted in the production of mostly phage head structures ...200011040123
molecular analysis of mutated lactobacillus acidophilus promoter-like sequence p15.the promoter-like sequence p15 that was previously cloned from the chromosome of lactobacillus acidophilus atcc 4356 is active in lactobacillus reuteri, lactobacillus plantarum, lactobacillus acidophilus, and escherichia coli, but not in lactococcus lactis. n-methyl-n-nitroso-n-guanidine (mnng) mutagenesis of p15 was used to select for a promoter active in l. lactis mg1363. molecular analysis of the mutated promoter (designated p16) revealed a 90 bp deletion and a t-->a transversion. this deleti ...200011068681
an explosive antisense rna strategy for inhibition of a lactococcal bacteriophage.the coding regions of six putative open reading frames (orfs) identified near the phage phi31 late promoter and the right cohesive end (cos) of lactococcal bacteriophage phi31 were used to develop antisense constructs to inhibit the proliferation of phage phi31. two middle-expressed orfs (orf 1 and orf 2) and four late-expressed orfs (orf 3 through orf 6) were cloned individually between the strong lactobacillus p6 promoter and the t7 terminator (t(t7)) to yield a series of antisense rna transcr ...200010618241
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
genetic analysis of chromosomal regions of lactococcus lactis acquired by recombinant lytic phages.recombinant phages are generated when lactococcus lactis subsp. lactis harboring plasmids encoding the abortive type (abi) of phage resistance mechanisms is infected with small isometric phages belonging to the p335 species. these phage variants are likely to be an important source of virulent new phages that appear in dairy fermentations. they are distinguished from their progenitors by resistance to abi defenses and by altered genome organization, including regions of l. lactis chromosomal dna ...200010698748
analysis of promoter sequences from lactobacillus and lactococcus and their activity in several lactobacillus species.promoter-active fragments were isolated from the genome of the probiotic organism lactobacillus rhamnosus strain gg using the promoter-probe vector pnz272. these promoter elements, together with a promoter fragment isolated from the vaginal strain lactobacillus fermentum br11 and two previously defined promoters (lactococcus lactis and lactobacillus acidophilus atcc 4356 slpa), were introduced into three strains of lactobacillus. primer-extension analysis was used to map the transcriptional star ...200010896218
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
the role of escherichia coli rnase e and rnase iii in the processing of the citqrp operon mrna from lactococcus lactis biovar diacetylactis.citrate transport in lactococcus lactis biovar diacetylactis (l. diacetylactis) is catalyzed by citrate permease p (citp), which is encoded by the plasmidic citp gene. two partial overlapping open reading frames citq and citr are located upstream of citp. these two genes, together with citp, constitute the citqrpoperon. in this report it was shown that in l. diacetylactis and escherichia coli, cit mrna is subject to the same specific cleavages at a complex secondary structure which includes the ...199910943565
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
cloning of branched chain amino acid biosynthesis genes and assays of alpha-acetolactate synthase activities in leuconostoc mesenteroides subsp. cremoris.a genomic library from leuconostoc mesenteroides subsp. cremoris (lmc) in escherichia coli was screened for alpha-acetolactate synthase (als) activity using a phenotypic test detecting the production of acetolactate or related c4 derivatives (diacetyl, acetoin or 2,3-butanediol) in the culture. four recombinant e. coli clones, with plasmids containing overlapping dna fragments and displaying anabolic als activity, were selected. this activity is encoded by an ilvb gene belonging to a putative op ...199910229948
histidinol phosphate phosphatase, catalyzing the penultimate step of the histidine biosynthesis pathway, is encoded by ytvp (hisj) in bacillus subtilis.the deduced product of the bacillus subtilis ytvp gene is similar to that of orf13, a gene of unknown function in the lactococcus lactis histidine biosynthesis operon. a b. subtilis ytvp mutant was auxotrophic for histidine. the only enzyme of the histidine biosynthesis pathway that remained uncharacterized in b. subtilis was histidinol phosphate phosphatase (holpase), catalyzing the penultimate step of this pathway. holpase activity could not be detected in crude extracts of the ytvp mutant, wh ...199910322033
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 chloride-inducible acid resistance mechanism in lactococcus lactis and its regulation.previously, a promoter was identified in lactococcus lactis that is specifically induced by chloride. here, we describe the nucleotide sequence and functional analysis of two genes transcribed from this promoter, gadc and gadb. gadc is homologous to putative glutamate-gamma-aminobutyrate antiporters of escherichia coli and shigella flexneri and contains 12 putative membrane-spanning domains. gadb shows similarity to glutamate decarboxylases. a l. lactis gadb mutant and a strain that is unable to ...19989484886
the s-layer gene of lactobacillus helveticus cnrz 892: cloning, sequence and heterologous expression.lactobacillus helveticus cnrz 892 contains a surface layer (s-layer) composed of protein monomers of 43 kda organized in regular arrays. the gene encoding this protein (slph) has been cloned in escherichia coli and sequenced. slph consists of 440 codons and is preceded by a ribosome-binding site (rbs) and followed by a putative rho-independent terminator. indeed, northern analysis revealed that slph is a monocistronic gene. the gene is preceded by a possible promotor of which the -35 and -10 hex ...19989534241
an origin of transfer (orit) on the conjugative element prs01 from lactococcus lactis subsp. lactis ml3.previous analysis of the tra1 region of the conjugative element prs01 from lactococcus lactis subsp. lactis ml3 suggested that an origin of transfer (orit) was present. deletion derivatives of this cloned tra1 region were assayed for mobilization in the presence of the wild-type prs01 element in trans. the prs01 orit was localized to a 446-nucleotide segment in the intergenic region between open reading frames ltrd and ltre. sequence analysis of this region revealed a cluster of direct and inver ...19989546191
acid stress, anaerobiosis and gadcb: lessons from lactococcus lactis and escherichia coli. 19989675796
transcriptional regulation and evolution of lactose genes in the galactose-lactose operon of lactococcus lactis ncdo2054.the genetics of lactose utilization within the slow-lactose-fermenting lactococcus lactis strain ncdo2054 was studied with respect to the organization, expression, and evolution of the lac genes. initially the beta-galactosidase gene (lacz) was cloned by complementation of an escherichia coli mutant on a 7-kb hpai fragment. nucleotide sequence analysis of the complete fragment revealed part of a gal-lac operon, and the genes were characterized by inactivation and complementation analyses and in ...19989733693
crystal structures of a unique thermal-stable thymidylate synthase from bacillus subtilis.unlike all other organisms studied to date, bacillus subtilis expresses two different thymidylate synthases: bsts-a and bsts-b. bsts-a displays enhanced enzymatic and structural thermal stability uncharacteristic of most tss. despite the high level of ts conservation across most species, bsts-a shares low sequence identity (<40%) with the majority of tss from other organisms. this ts and the tss from lactococcus lactis and phage phi3t-to which it is most similar-have been of interest for some ti ...19989778348
clustered organization and transcriptional analysis of a family of five csp genes of lactococcus lactis mg1363.a family of genes encoding cold-shock proteins, named cspa, cspb, cspc, cspd and cspe, was cloned and sequenced from lactococcus lactis mg1363. the genes cspa and cspb and the genes cspc and cspd are located in tandem repeats, an organization of csp genes that has never been encountered before. the five genes encode small (7.1-7.6 kda) proteins with high mutual sequence identities (up to 85%) and high identities (about 45-65%) with the major cold-shock proteins from escherichia coli (cspa) and b ...19989802030
cloning, expression, and chromosomal stabilization of the propionibacterium shermanii proline iminopeptidase gene (pip) for food-grade application in lactococcus lactis.proline iminopeptidase produced by propionibacterium shermanii plays an essential role in the flavor development of swiss-type cheeses. the enzyme (pip) was purified and characterized, and the gene (pip) was cloned and expressed in escherichia coli and lactococcus lactis, the latter species being an extensively studied, primary cheese starter culture that is less fastidious in its growth condition requirements than p. shermanii. the levels of expression of the pip gene could be enhanced with a f ...19989835556
persistence of escherichia coli o157:h7 in dairy fermentation systems.we examined (i) the persistence of escherichia coli o157:h7 as a postpasteurization contaminant in fermented dairy products; (ii) the ability of e. coli o157:h7 strains with and without the general stress regulatory protein, rpos, to compete with commercial starter cultures in fermentation systems; and (iii) the survival of e. coli o157:h7 in the yogurt production process. in commercial products inoculated with 10(3) cfu/ml, e. coli o157:h7 was recovered for up to 12 days in yogurt (ph 4.0), 28 ...19989874336
double-glycine-type leader peptides direct secretion of bacteriocins by abc transporters: colicin v secretion in lactococcus lactis.many non-lantibiotic bacteriocins of lactic acid bacteria are produced as precursors which have n-terminal leader peptides that share similarities in amino acid sequence and contain a conserved processing site of two glycine residues in positions -1 and -2. a dedicated atp-binding cassette (abc) transporter is responsible for the proteolytic cleavage of the leader peptides and subsequent translocation of the bacteriocins across the cytoplasmic membrane. to investigate the role that these leader ...19979106219
structure-function relationships within the peptide deformylase family. evidence for a conserved architecture of the active site involving three conserved motifs and a metal ion.thermus thermophilus peptide deformylase was characterized. its enzymatic properties as well as its organization in domains proved to share close resemblances with those of the escherichia coli enzyme despite few sequence identities. in addition to the hexxh signature sequence of the zinc metalloprotease family, a second short stretch of strictly conserved amino acids was noticed, egcls, the cysteine of which corresponds to the third zinc ligand. the study of site-directed mutants of the e. coli ...19979126850
cloning and functional expression in escherichia coli of the gene encoding the di- and tripeptide transport protein of lactobacillus helveticus.the gene encoding the di- and tripeptide transport protein (dtpt) of lactobacillus helveticus (dtptlh) was cloned with the aid of the inverse pcr technique and used to complement the dipeptide transport-deficient and proline-auxotrophic escherichia coli e1772. functional expression of the peptide transporter was shown by the uptake of prolyl-[14c] alanine in whole cells and membrane vesicles. peptide transport via dtpt in membrane vesicles is driven by the proton motive force. the system has spe ...19979172341
identification of a cold shock gene in lactic acid bacteria and the effect of cold shock on cryotolerance.when lactic acid bacterial cultures were frozen at -20 degrees c for 24 h, the cell viability decreased drastically, but when they were cold shocked at 10 degrees c for 2 h prior to freezing, viability improved significantly for the lactococcus lactis subsp. lactis strains (25-37%) and pediococcus pentosaceus po2 (18%), but not for the lactococcus lactis subsp. cremoris strains tested or for one strain of lactobacillus helveticus lb1 and streptococcus thermophilus ts2. when the period for cold s ...19979175562
characterization of escherichia coli nrdh. a glutaredoxin-like protein with a thioredoxin-like activity profile.ribonucleotides are converted to deoxyribonucleotides by ribonucleotide reductases. either thioredoxin or glutaredoxin is a required electron donor for class i and ii enzymes. glutaredoxins are reduced by glutathione, thioredoxins by thioredoxin reductase. recently, a glutaredoxin-like protein, nrdh, was isolated as the functional electron donor for a nrdef ribonucleotide reductase, a class ib enzyme, from lactococcus lactis. the absence of glutathione in this bacterium raised the question of th ...19979218434
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
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
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
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
nisin z, mutant nisin z and lacticin 481 interactions with anionic lipids correlate with antimicrobial activity. a monolayer study.monomolecular layers of lipids at the air/water interface have been used as a model membrane to study membrane interactions of the lantibiotic nisin. the natural lantibiotics nisin a and nisin z proved to have a high affinity for the anionic lipids phosphatidylglycerol and bis(phosphatidyl)glycerol (cardiolipin). the interaction with zwitterionic phopholipids or neutral lipids is very low at surface pressures higher than 32 mn/m. nisin, nisin mutants and lacticin 481 show a remarkable correlatio ...19968631341
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