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protein export elements from lactococcus lactis.broad-host-range plasmids carrying alpha-amylase or beta-lactamase reporter genes lacking a signal sequence were used to select export elements from lactococcus lactis chromosomal dna that could function as signal sequences. fragments containing such elements were identified by their ability to direct the export of the reporter proteins in escherichia coli. several of the selected export elements were also active in bacillus subtilis and l. lactis, although the efficiencies depended strongly on ...19921406586
genetic analysis of scra and scrb from streptococcus sobrinus 6715.a dna fragment containing scra and scrb, which encode enzyme ii of the phosphoenolpyruvate-dependent sucrose phosphotransferase system and sucrose-6-phosphate hydrolase, respectively, was isolated from a lambda gt10 genomic dna library of streptococcus sobrinus 6715. both genes were located on a 4.2-kb dna fragment which was maintained stably in escherchia coli on low-copy-number vector pgb2. the recombinant e. coli clone expressed sucrose-hydrolytic activity on macconkey agar base supplemented ...19921500184
characterization of lactococcus lactis phage antigens.phage phi 197 is representative of a widespread lactococcal phage group characterized by a particular morphology (prolate head with a noncontractile tail). in order to develop an immunoenzymatic phage detection test, fusion proteins containing beta-galactosidase fused to epitopes of phage phi 197 structural proteins were constructed by cloning random dna fragments from the phage genome upstream of a lacz gene on a plasmid vector. recombinant plasmids containing certain fragments encoded the synt ...19921514794
lactococcal proteinase maturation protein prtm is a lipoprotein.the production of enzymatically active proteinase by lactococci requires the joint presence of a proteinase gene, prtp, and a gene encoding a maturation protein, prtm. a 32-kda protein produced by escherichia coli upon expression of the prtm gene under the direction of the t7 rna polymerase promoter was purified and used to obtain prtm-specific antibodies. with these antibodies, immunogold labeling of lactococcal cells revealed that prtm was associated with the lactococcal cell envelope. western ...19911906066
isolation, sequence and expression in escherichia coli, bacillus subtilis and lactococcus lactis of the dnase (streptodornase)-encoding gene from streptococcus equisimilis h46a.a partial library of bcli-generated chromosomal dna fragments from streptococcus equisimilis h64a (lancefield group c) was constructed in escherichia coli. clones displaying either streptokinase or deoxyribonuclease (streptodornase; sdc) activities were isolated. the gene (sdc) expressing the sdc activity was allocated on the 1.1-kb acci dna subfragment. sequence analysis of this dna fragment revealed the presence of one open reading frame, which could encode a protein of 36.8 kda. the n-termina ...19911937032
cloning of usp45, a gene encoding a secreted protein from lactococcus lactis subsp. lactis mg1363.we have cloned usp45, a gene encoding an extracellular secretory protein of lactococcus lactis subsp. lactis strain mg1363. unidentified secreted 45-kda protein (usp45) is secreted by every mesophilic l. lactis strain we tested so far and it is chromosomally encoded. the nucleotide sequence of the usp45 gene revealed an open reading frame of 1383 bp encoding a protein of 461 amino acids (aa), composed of a 27-aa signal peptide and a mature protein initiated at asp28. the gene contains a consensu ...19902123812
characterization of the lactose-specific enzymes of the phosphotransferase system in lactococcus lactis.the plasmid-encoded lactose genes of the lactococcus lactis phosphotransferase system encoding enzyme iiilac (lacf) and enzyme iilac (lace) have been identified and cloned in escherichia coli and l. lactis. nucleotide sequence and transcription analysis showed that these genes are organized into a lactose-inducible operon with the gene order lacf-lace-lacg-lacx, the latter two genes encoding phospho-beta-galactosidase and a 34-kda protein with an unknown function, respectively. the lac-operon is ...19902125052
isolation of a replication region of a large lactococcal plasmid and use in cloning of a nisin resistance determinant.the replication region of a 28-kilobase-pair (kbp) cryptic plasmid from lactococcus lactis subsp. lactis biovar diacetylactis ssd207 was cloned in l. lactis subsp. lactis mg1614 by using the chloramphenicol resistance gene from the streptococcal plasmid pgb301 as a selectable marker. the resulting 8.1-kbp plasmid, designated pvs34, was characterized further with respect to host range, potential cloning sites, and location of replication gene(s). in addition to lactococci, pvs34 transformed lacto ...19902389931
cloning and characterization of the tetracycline resistance determinant of and several promoters from within the conjugative transposon tn919.tn919 is a 15- to 16-kilobase (kb) tetracycline resistance conjugative transposon that was originally isolated from streptococcus sanguis fc1. the tetracycline resistance determinant (tet) was found on a 4.2-kb hindii fragment by in vitro deletion analysis. this fragment was subcloned to a pwv01 origin capable of directing replication in escherichia coli, bacillus subtilis, and streptococcus lactis, and expression was observed in all three genera. in all cases, expression was weaker when only th ...19882839111
the cytochrome c oxidase test for the rapid detection of psychrotrophic bacteria in milk.a new, rapid, simple and cheap method for the detection of the predominant psychrotrophic bacteria in raw and pasteurized milks is described, using tetramethyl-p-phenylene-diamine dihydrochloride to detect cytochrome c oxidase which in general is not present in the non-psychrotrophic bacterial milk flora. the test is sensitive to samples containing over 10(4) organisms/ml. correlation coefficients of 0.92 and 0.84 between dye oxidation and viable counts for pasteurized and raw milk samples, resp ...19852995302
cloning, expression and location of the streptococcus lactis gene for phospho-beta-d-galactosidase.genes for lactose catabolism and proteinase production in streptococcus lactis 712 are encoded by a 56.5 kb metabolic plasmid, plp712. a lactose mini-plasmid of only 23.7 kb, pmg820, was constructed by introducing two deletions into plp712, and was cloned as two segments of dna into the escherichia coli vector pat153 using restriction endonuclease psti. the lactose genetic region of plp712, which has been defined by deletion and restriction mapping, was cut into two parts by this process. when t ...19863086494
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
herd incidence of bovine mastitis in four danish dairy districts. i. the prevalence and mastitogenic effect of micro-organisms in the mammary glands of cows. 19744213559
comparative resistance of nonsporogenic bacteria to low-temperature gamma irradiation.a total of 36 microorganisms, comprising 19 species of 11 genera, were screened for radiation resistance with (60)co gamma rays at a radiation temperatore of -80 +/- 2 c in phosphate buffer (ph 7.0) under vacuum. micrococcus radiodurans was the most resistant organism. an initial population of 2.8 x 10(5) cells per dose of this species survived 2.4 but not 2.7 mrad. of the remaining 18 species with initial populations of about 10(6) cells per dose, streptococcus faecium survived 0.9 to 1.5 mrad, ...19734572982
[laboratory diagnosis of mastitis]. 19724628197
evaluation of the direct epifluorescent filter technique for assessing the hygienic condition of milking equipment.the hygienic condition of 6 milking installations, 3 sanitized by circulation cleaning (cc) with chlorine-based chemicals and 3 by flushing with acidified boiling water (abw), was tested using rinses of quarter strength ringer's solution. the bacterial content of the rinses was determined using both colony counts and the direct epifluorescent filter technique (deft). a comparison of testing methods gave correlation coefficients between colony count and deft of 0.82 for plants using cc and 0.46 f ...19836341424
improvement of solubility and stability of the antimicrobial peptide nisin by protein engineering.nisin is a 3.4-kda antimicrobial peptide that, as a result of posttranslational modifications, contains unsaturated amino acids and lanthionine residues. it is applied as a preservative in various food products. the solubility and stability of nisin and nisin mutants have been studied. it is demonstrated that nisin mutants can be produced with improved functional properties. the solubility of nisin a is highest at low ph values and gradually decreases by almost 2 orders of magnitude when the ph ...19957487019
physiological and genetic regulation of rrna synthesis in lactococcus.the macromolecular composition of lactococcus was regulated by growth rate in the same general way as that of less fastidious bacteria such as escherichia coli and salmonella typhimurium. the ratios of rna:dna and rna:protein increased approximately threefold over a 13.5-fold increase in growth rate, whereas the ratio of dna:protein remained approximately constant. using reporter genes fused to a dna fragment of a cloned lactococcal rrna operon, promoter activity was located upstream of the 16s ...19937504067
transformation of lactococcus by electroporation. 19957550735
the cellular location and effect on nisin immunity of the nisi protein from lactococcus lactis n8 expressed in escherichia coli and l. lactis.lactococcus lactis cells secreting the lantibiotic nisin, commercially used for food preservation, must protect their cell membrane against the pore-forming activity of extracellular nisin. the nisi gene product has been suggested to be a lipoprotein, which due to the location on the extracellular surface would be an ideal candidate for an immunity protein. in vivo labelling of nisi from l. lactis n8 expressed in escherichia coli proved that nisi is a lipoprotein. expression of nisi in the nisin ...19957557313
a family of bacteriocin abc transporters carry out proteolytic processing of their substrates concomitant with export.lantibiotic and non-lantibiotic bacteriocins are synthesized as precursor peptides containing n-terminal extensions (leader peptides) which are cleaved off during maturation. most non-lantibiotics and also some lantibiotics have leader peptides of the so-called double-glycine type. these leader peptides share consensus sequences and also a common processing site with two conserved glycine residues in positions -1 and -2. the double-glycine-type leader peptides are unrelated to the n-terminal sig ...19957565085
cloning and nucleotide sequencing of l-lactate dehydrogenase gene from streptococcus thermophilus m-192.the gene encoding l-lactate dehydrogenase (ldh) was cloned from an industrial dairy strain of streptococcus thermophilus m-192 using a synthetic oligonucleotide probe based on the n-terminal amino acid sequence of the purified enzyme, and its nucleotide sequence was determined. the enzyme was deduced to have 328 amino acid residues with a molecular weight of 35,428 and found to have high sequence similarity to ldhs from other lactic acid bacteria (89.0% to streptococcus mutans, 76.3% to lactococ ...19947765475
molecular cloning and nucleotide sequence of the gene encoding the major peptidoglycan hydrolase of lactococcus lactis, a muramidase needed for cell separation.a gene of lactococcus lactis subsp. cremoris mg1363 encoding a peptidoglycan hydrolase was identified in a genomic library of the strain in puc19 by screening escherichia coli transformants for cell wall lysis activity on a medium containing autoclaved, lyophilized micrococcus lysodeikticus cells. in cell extracts of l. lactis mg1363 and several halo-producing e. coli transformants, lytic bands of similar sizes were identified by denaturing sodium dodecyl sulfate (sds)-polyacrylamide gels contai ...19957883712
expression, purification, and characterization of thymidylate synthase from lactococcus lactis.the thymidylate synthase (ts) gene from lactococcus lactis has been highly expressed in escherichia coli. the ts protein was purified by sequential chromatography on q-sepharose and phenyl-sepharose. six grams of cell pellet yielded 140 mg of homogeneous ts. ts is a highly conserved enzyme, and several of the conserved amino acid residues that have been implicated in catalytic function are altered in l. lactis ts. by use of a 3-dimensional homology model, we have predicted covariant changes that ...19947920258
cloning, sequencing and characterization of the pepip gene encoding a proline iminopeptidase from lactobacillus delbrueckii subsp. bulgaricus cnrz 397.the proline iminopeptidase (pepip) of lactobacillus delbrueckii subsp. bulgaricus is a major peptidase located in the cell envelope. its structural gene (pepip) has been cloned into puc18 and expressed at a very high level in escherichia coli to give a pepip activity 15,000-fold higher than that found in l. delbrueckii subsp. bulgaricus. the nucleotide sequence of the pepip gene revealed an open reading frame of 295 codons encoding a protein with a predicted m(r) of 33,006, which is consistent w ...19948012575
two different dihydroorotate dehydrogenases in lactococcus lactis.the pyrimidine de novo biosynthesis pathway has been characterized for a number of organisms. the general pathway consists of six enzymatic steps. in the characterization of the pyrimidine pathway of lactococcus lactis, two different pyrd genes encoding dihydroorotate dehydrogenase were isolated. the nucleotide sequences of the two genes, pyrda and pyrdb, have been determined. one of the deduced amino acid sequences has a high degree of homology to the saccharomyces cerevisiae dihydroorotate deh ...19948021180
sequence analysis of the lysin gene region of the prolate lactococcal bacteriophage c2.approximately 80% of the genome of the prolate-headed lactococcal bacteriophage c2 was cloned into shuttle vectors psa3 and pfx3 in escherichia coli and transferred to lactococcus lactis. a 1.67-kilobase ecorv fragment containing the gene for the phage lysin was identified and the position and orientation of the phage lysin gene in the physical map of the phage were determined. the phage lysin was expressed in e. coli and its sequence was determined and compared with the sequences of other bacte ...19938221377
purification, crystallization, and preliminary x-ray analysis of pepx, an x-prolyl dipeptidyl aminopeptidase from lactococcus lactis.the x-prolyl dipeptidyl aminopeptidase pepx, a serine peptidase isolated originally from lactococcus lactis subsp lactis ncdo 763, was cloned and overproduced in escherichia coli. the enzyme was isolated in its active form in two purification steps. crystals of pepx were grown by the hanging drop vapor diffusion method using polyethyleneglycol 4000 as precipitant at ph 5.0. the crystals are orthorhombic with cell dimensions a = 92.8 a, b = 102.6 a, and c = 101.6 a, space group p2(1)2(1)2, and pr ...19958592708
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
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
nucleotide sequence and analysis of pwc1, a pc194-type rolling circle replicon in lactococcus lactis.a 2.8-kb cryptic plasmid showing no homology to either pfx3 (rolling circle, pe194-type) or pci305 (theta-type) lactococcal replicons was identified in lactococcus lactis subsp. cremoris 2204. the plasmid, pwc1, was compatible with both pci3340 (a pci305 derivative) and pfx3 in l. lactis subsp. cremoris 2204. sequence analysis of pwc1 showed one major orf encoding a protein with a deduced size of 316 amino acids (aa). database comparisons showed that the protein was distinct from the pfx- and pc ...19968700966
[isolation and reassociation of acetogen and methanogen in a syntrophobic coculture degrading butyrate anaerobically].anaerobic coculture bf2 which degraded butyrate into acetate and produced methane was isolated from granular methanogenic sludge. the coculture is associated syntrophically the syntrophomonas subsp. saponavida strain cf2 with methanobacterium formicicum strain mf2 and appeared to degraded c4 approximately c18 fatty acids including isobutyrate. the optimal temperature and ph for growth was 37 degrees c and 7.7 respectively. the strain cf2 was obtained in pure culture with crotonate as substrate a ...19958745550
sequence analysis and identification of the pyrkdbf operon from lactococcus lactis including a novel gene, pyrk, involved in pyrimidine biosynthesis.three genes encoding enzymes involved in the biosynthesis of pyrimidines have been found to constitute an operon in lactococcus lactis. two of the genes are the well-known pyr genes pyrdb and pyrf, encoding dihydroorotate dehydrogenase and orotidine monophosphate decarboxylase, respectively. the third gene encodes a protein which was shown to be necessary for the activity of the pyrdb-encoded dihydroorotate dehydrogenase; we propose to name the gene pyrk. the pyrk-encoded protein is homologous t ...19968759867
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
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
characterization and overexpression of the lactococcus lactis pepn gene and localization of its product, aminopeptidase n.the chromosomal pepn gene encoding lysyl-aminopeptidase activity in lactococcus lactis has been identified in a lambda embl3 library in escherichia coli by using an immunological screening with antiserum against a purified aminopeptidase fraction. the pepn gene was localized and subcloned in e. coli on the basis of its expression and hybridization to a mixed-oligonucleotide probe for the previously determine n-terminal amino acid sequence of lysyl-aminopeptidase (p. s. t. tan and w. n. konings, ...19911685079
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
enhancement of the chemical and antimicrobial properties of subtilin by site-directed mutagenesis.subtilin and nisin are gene-encoded antibiotic peptides that are ribosomally synthesized by bacillus subtilis and lactococcus lactis, respectively. gene-encoded antibiotics are unique in that their structures can be manipulated by mutagenesis of their structural genes. although subtilin and nisin share considerable structural homology, subtilin has a greater tendency than nisin to undergo spontaneous inactivation. this inactivation is a accompanied by chemical modification of the dehydroalanine ...19921460009
engineering dehydrated amino acid residues in the antimicrobial peptide nisin.the small antimicrobial peptide nisin, produced by lactococcus lactis, contains the uncommon amino acid residues dehydroalanine and dehydrobutyrine and five thio ether bridges. since these structures are posttranslationally formed from ser, thr, and cys residues, it is feasible to study their role in nisin function and biosynthesis by protein engineering. here we report the development of an expression system for mutated nisin z (nisz) genes, using nisin a producing l. lactis as a host. replacem ...19921447185
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
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
effect of lipophilicity of nitroimidazoles on radiosensitization of hypoxic bacterial cells in vitro.the effect of radiosensitization of hypoxic bacterial cells by 9 nitroimidazoles was measured in the bacterial strains e. coli ab 1157 and s. lactis 712. seven of these compounds were similar to misonidazole in their redox properties, but differed widely in their lipophilicites. the dependence of sensitization enhancement on reduction potential was similar to that reported in mammalian cells. the efficiency of sensitization was similar for compounds of low lipophilicity, but increased if the oct ...1979109112
two lactococcus lactis genes, including lacx, cooperate to trigger an sos response in a reca-negative background.a 4.3-kb ecori fragment from a lactococcus lactis genomic library alleviates the methyl methanesulfonate, mitomycin c, and uv sensitivities of an escherichia coli reca mutant (m. novel, x. f. huang, and g. novel, fems microbiol. lett. 72:309-314, 1990). it complements reca1 and delta reca mutations but not reca13. three proteins (with molecular masses of 20, 35, and 23 kda) were produced from this fragment in a t7-directed system, and three corresponding genes were detected by dna sequencing, na ...19957814316
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
medium-dependent regulation of proteinase gene expression in lactococcus lactis: control of transcription initiation by specific dipeptides.transcriptional gene fusions with the escherichia coli beta-glucuronidase gene (gusa) were used to study the medium- and growth-dependent expression of the divergently transcribed genes involved in proteinase production (prtp and prtm) of lactococcus lactis sk11. the results show that both the prtp and prtm genes are controlled at the transcriptional level by the peptide content of the medium and, to a lesser extent, by the growth rate. a more than 10-fold regulation in beta-glucuronidase activi ...19957768792
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
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
radiosensitization of hypoxic bacterial cells by nitroimidazoles of low lipophilicity: steady-state and rapid-mix studies. 19816782616
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
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
functional reconstitution of prokaryote and eukaryote membrane proteins.a new strategy for the functional reconstitution of membrane proteins is described. this approach introduces a new class of protein stabilizing agents--osmolytes--whose presence at high concentration (10-20%) during detergent solubilization prevents the inactivations that normally occur when proteins are extracted from natural membranes. osmolytes that act in this way include compounds such as glycerol and higher polyols (erythritol, xylitol, sorbitol), sugars (glucose, trehalose), and certain a ...19892492790
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
staphylococcal phosphoenolpyruvate-dependent phosphotransferase system: molecular cloning and nucleotide sequence of the staphylococcus carnosus ptsi gene and expression and complementation studies of the gene product.a digoxigenin-labeled dna probe that was complementary to the gene ptsh and the beginning of the gene ptsi was used to clone a 3.2-kb hincii-bamhi restriction fragment containing the complete ptsi gene of staphylococcus carnosus. the restriction fragment was cloned in the antisense orientation to the lac promoter in the low-copy-number vector psu18. the nucleotide sequences of the ptsi gene, which encodes enzyme i (ec 2.7.3.9), and the corresponding flanking regions were determined. the primary ...19921551842
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
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
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
genetic organization of the mle locus and identification of a mler-like gene from leuconostoc oenos.characterization of the mle locus harboring the malolactic enzyme gene mlea and malate permease gene mlep from leuconostoc oenos was completed in this study by mrna analysis. northern (rna) blot experiments revealed a 2.6-kb transcript, suggesting an operon structure harboring mlea and mlep genes. primer extension analysis showed that the mle operon has a single transcription start site located 17 nucleotides upstream of the atg translation start site for the mlea gene. we found sequences, ttgac ...19968953720
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
effect of bromidehypochlorite bactericides on microorganisms.a new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% "available chlorine" and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% "available chlorin ...196213977149
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
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
the reca gene of lactococcus lactis: characterization and involvement in oxidative and thermal stress.the role of reca in lactococcus lactis, a microaerophilic fermenting organism, was examined by constructing a reca-disrupted strain. this single alteration had a surprisingly pleiotropic effect. in addition to its roles in homologous recombination and dna repair, reca is also involved in responses to oxygen and heat stresses. we found that oxygen stress induced by aeration causes reductions in growth and stationary-phase survival of the reca strain. toxicity is a consequence of hydroxyl radical ...19958594331
controlled expression and structural organization of a lactococcus lactis bacteriophage lysin encoded by two overlapping genes.the phi vml3 bacteriophage lysin is specific for lactococci and could be used to promote enzyme release during cheese manufacture. the level of lysin expression from the cloned gene using its own upstream sequences is very low. expression in escherichia coli by using a synthetic hybrid lysin gene and a series of bal 31 deletions of the original cloned dna fragment suggested that the start of the gene had previously been incorrectly assigned. reevaluation of homology between the lysin and bacillu ...19947944354
cloning of the citrate permease gene of lactococcus lactis subsp. lactis biovar diacetylactis and expression in escherichia coli.the citrate plasmid (cit+ plasmid) from lactococcus lactis subsp. lactis biovar diacetylactis was cloned into the ecori site of plasmid puc18. this recombinant plasmid enabled escherichia coli k-12 to transport and utilize citrate as a source of energy, indicating expression of the citrate permease from l. lactis biovar diacetylactis. the citrate permease was under the control of the lac promoter of puc18. genetic expression of the cit+ plasmid in maxicells revealed that the plasmid encoded two ...19902117878
the di- and tripeptide transport protein of lactococcus lactis. a new type of bacterial peptide transporter.lactococcus lactis takes up di- and tripeptides via a proton motive force-dependent carrier protein. the gene (dtpt) encoding the di-tripeptide transport protein of l. lactis was cloned by complementation of a dipeptide transport-deficient and proline auxotrophic escherichia coli strain. functional expression of the dipeptide transport gene was demonstrated by uptake studies of alanyl-[14c]glutamate and other peptides in e. coli cells. the di-tripeptide transport protein catalyzes proton motive ...19948157671
identification and characterization of genes involved in excision of the lactococcus lactis conjugative transposon tn5276.the 70-kb transposon tn5276, originally detected in lactococcus lactis nizo r5 and carrying the genes for nisin production and sucrose fermentation, can be conjugally transferred to other l. lactis strains. sequence analysis and complementation studies showed that the right end of tn5276 contains two genes, designated xis and int, which are involved in excision. the 379-amino-acid int gene product shows high (up to 50%) similarity with various integrases, including that of the tn916-related conj ...19948157585
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
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
evidence for a large dispensable segment in the subtilisin-like catalytic domain of the lactococcus lactis cell-envelope proteinase.the lactococcus lactis sk11 cell-envelope proteinase contains various inserts, located in external loops of the catalytic domain compared with related subtilisins. in this study, protein engineering was employed to determine the function of the largest loop insertion (residues 238-388) relative to the subtilisin structure. by site-directed mutagenesis we have deleted the fragment of the proteinase gene encoding these 151 residues and analyzed the mutant delta 238-388 proteinase for activity, (au ...19947528919
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
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
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
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
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
molecular cloning, transcriptional analysis, and nucleotide sequence of lacr, a gene encoding the repressor of the lactose phosphotransferase system of lactococcus lactis.the repressor gene (lacr) of the lactose phosphotransferase system of lactococcus lactis subsp. lactis strain mg1820 has been cloned and characterized. transcription of lacr, into a 1.2-kilobase monocistronic messenger, is repressed approximately 5-fold during growth on lactose. nucleotide sequence analysis of the lacr gene showed the presence of an open reading frame of 861 base pairs. the deduced amino acid sequence of lacr is homologous to three escherichia coli regulatory proteins (deor, fuc ...19902120234
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
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
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