autolysis of lactococcus lactis caused by induced overproduction of its major autolysin, acma.the optical density of a culture of lactococcus lactis mg1363 was reduced more than 60% during prolonged stationary phase. reduction in optical density (autolysis) was almost absent in a culture of an isogenic mutant containing a deletion in the major autolysin gene, acma. an acma mutant carrying multiple coples of a plasmid encoding acma lysed to a greater extent than the wild-type strain did. intercellular action of acma was shown by mixing end-exponential-phase cultures of an acma deletion mu ...19979212419
rusa proteins from the extreme thermophile aquifex aeolicus and lactococcal phage r1t resolve holliday junctions.the rusa protein of escherichia coli is a dna structure-specific endonuclease that resolves holliday junction intermediates formed during dna replication, recombination and repair by introducing symmetrically paired incisions 5' to cc dinucleotides. it is encoded by the defective prophage dlp12, which raises the possibility that it may be of bacteriophage origin. we show that rusa-like sequences are indeed often associated with prophage sequences in the genomes of several bacterial species. they ...200211972790
characterization of the putative replisome organizer of the lactococcal bacteriophage r1t.analysis of the nucleotide sequence of the genome of the lactococcal bacteriophage r1t showed that it may encode at least two proteins involved in dna replication. on the basis of its similarity with the g38p protein encoded by the bacillus subtilis phage spp1, the product of orf11 (pro11) is thought to be involved in the initiation of phage dna replication. this protein was overexpressed in lactococcus lactis and partially purified. gel retardation analysis using various r1t dna fragments indic ...200212239299
phages of dairy bacteria.bacteriophages of lactic acid bacteria are a threat to industrial milk fermentation. owing to their economical importance, dairy phages became the most thoroughly sequenced phage group in the database. comparative genomics identified related cos-site and pac-site phages, respectively, in lactococci, lactic streptococci and lactobacilli. each group was represented with closely related temperate and virulent phages. over the structural genes their gene maps resembled that of lambdoid coliphages, s ...200111544357
a chloride-inducible gene expression cassette and its use in induced lysis of lactococcus lactis.a chloride-inducible promoter previously isolated from the chromosome of lactococcus lactis (j. w. sanders, g. venema, j. kok, and k. leenhouts, mol. gen. genet., in press) was exploited for the inducible expression of homologous and heterologous genes. an expression cassette consisting of the positive-regulator gene gadr, the chloride-inducible promoter pgad, and the translation initiation signals of gadc was amplified by pcr. the cassette was cloned upstream of escherichia coli lacz, the holin ...19979406408
design of thermolabile bacteriophage repressor mutants by comparative molecular modeling.comparative molecular modeling was performed with repressor protein rro of the temperate lactococcus lactis bacteriophage r1t using the known 3d-structures of related repressors in order to obtain thermolabile derivatives of rro. rro residues presumed to stabilize a nonhomologous but structurally conserved hydrophobic pocket, which was shown to be important for thermostability of the escherichia coli bacteriophage lambda repressor ci, were randomized. of the derivatives that exhibited various te ...19979335049
sequence analysis and molecular characterization of the temperate lactococcal bacteriophage r1t.the temperate lactococcal bacteriophage r1t was isolated from its lysogenic host and its genome was subjected to nucleotide sequence analysis. the linear r1t genome is composed of 33,350 bp and was shown to possess 3' staggered cohesive ends. fifty open reading frames (orfs) were identified which are, probably, organized in a life-cycle-specific manner. nucleotide sequence comparisons, n-terminal amino acid sequencing and functional analyses enabled the assignment of possible functions to a numb ...19968730875
inducible gene expression mediated by a repressor-operator system isolated from lactococcus lactis bacteriophage r1t.a regulatory region of the temperate lactococcus lactis bacteriophage r1t chromosome has been cloned and characterized. it encompasses the two divergently oriented genes rro, encoding the phage repressor, and tec. both genes, of which the transcription start sites have been mapped, are preceded by consensus -35 and -10 promoter sequences. the region contains three 21 bp direct repeats with internal dyad symmetry which probably act as operators. two of these repeats partially overlap the two prom ...19968730874
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