| localization of separate genetic loci for reduced sensitivity towards small isometric-headed bacteriophage sk1 and prolate-headed bacteriophage c2 on pgbk17 from lactococcus lactis subsp. lactis kr2. | the mechanism of reduced sensitivity to the small isometric-headed bacteriophage sk1 encoded on a 19-kilobase (kb) hpaii fragment subcloned from pkr223 of lactococcus lactis subsp. lactis kr2 was examined. the reduced sensitivity to phage sk1 was due to a modest restriction/modification (r/m) system that was not active against prolate-headed phage c2. the genetic loci for the r/m system against sk1 and the abortive phage infection (abi) mechanism effective against phage c2 were then localized by ... | 1989 | 16348036 |
| transduction of concatemeric plasmids containing the cos site of lactococcus lactis bacteriophage sk1. | lactococcus lactis bacteriophage sk1 can transduce plasmids containing the phage cos site and surrounding dna sequences at frequencies as high as 2x10(-3) transductants per pfu. deletion analysis demonstrated that the presence of phage dna spanning cos and putative r sites were the most important for efficient plasmid transduction. inserts of 440 bp containing cos and the r sites were sufficient to induce transduction frequencies of 10(-4) transductants per pfu. the role of the r1 site was inves ... | 2002 | 12423757 |
| cloning of genomic dna of lactococcus lactis that restores phage sensitivity to an unusual bacteriophage sk1-resistant mutant. | an unusual, spontaneous, phage sk1-resistant mutant (rmsk1/1) of lactococcus lactis c2 apparently blocks phage dna entry into the host. although no visible plaques formed on rmsk1/1, this host propagated phage at a reduced efficiency. this was evident from center-of-infection experiments, which showed that 21% of infected rmsk1/1 formed plaques when plated on its phage-sensitive parental strain, c2. moreover, viable cell counts 0 and 4 h after infection were not significantly different from thos ... | 2001 | 11157245 |
| analysis of the dna sequence, gene expression, origin of replication and modular structure of the lactococcus lactis lytic bacteriophage sk1. | bacteriophage sk1 is a small isometric-headed lytic phage belonging to the 936 species. it infects lactococcus lactis, a commonly used dairy starter organism. nucleotide sequence data analysis indicated that the sk1 genome is 28,451 nucleotides long and contains 54 open reading frames (orfs) of 30 or more codons, interspersed with three large intergenic regions. the nucleotide sequence of several of the sk1 orfs demonstrated significant levels of identity to genes (many encoding proteins of unkn ... | 1997 | 9383189 |
| analysis of the cos region of the lactococcus lactis bacteriophage sk1. | the location, structure and nature of the cos site of the lactococcus lactis bacteriophage sk1 was determined using a taq dna polymerase runoff sequencing technique. the cos site contains a single-stranded 3' overhang of 11 nucleotides. the region surrounding cos contains several features which may be involved in the binding and catalytic action of a phage terminase. these include four putative terminase-binding sites which show some homology to lambda r-sites, an 11-bp direct repeat, a 10-bp in ... | 1994 | 8125289 |
| temporal transcription map of the lactococcus lactis bacteriophage sk1. | bacteriophage sk1 is a small isometric-headed lytic phage that infects lactococcus lactis. the phage has a linear double-stranded dna genome of 28 kbp, with cohesive ends. rna was prepared from phage-infected l. lactis cells harvested at various intervals after infection, and the rna molecules were resolved by electrophoresis. northern blots of these gels were hybridized with sk1 dna probes and the results obtained from these experiments, together with the results of primer extension analyses, e ... | 1994 | 7952177 |