title: Genome analysis of the obligately lytic bacteriophage 4268 of Lactococcus lactis provides insight into its adaptable nature.
abstract: Analysis of the complete nucleotide sequence of the lactococcal phage 4268, which is lytic for the cheese starter Lactococcus lactis DPC4268, is presented. Phage 4268 has a linear genome of 36,596 bp, which is modularly organised and encompasses 49 open reading frames. Putative functions were assigned to approximately 45% of the predicted products of these open reading frames based on sequence similarity with known proteins, N-terminal sequence analysis and identification of conserved domains. Significantly, a segment of the genome has homology to the recently sequenced lysogenic module in lactococcal phage phi31 that contains a lytic switch but no phage integrase or attachment site. This suggests that it is derived from a prophage. A phage 4268-encoded and a host-encoded methylase were found to be highly similar, having only two nucleotide mismatches, suggesting that the phage acquired the methylase gene to protect it from a host endonuclease. Comparative genomic analysis revealed significant homology between phage 4268 and the lactococcal phage BK5-T. The comparative analysis also supported the classification of phage 4268 and other BK5-T-related phage as separate from the proposed P335 species of lactococcal phage.
authors.affiliation: Department of Microbiology, University College Cork, Ireland.
authors.forename: Maeve
authors.initials: M
authors.lastname: Trotter
authors.forename: Olivia
authors.initials: O
authors.lastname: McAuliffe
authors.forename: Michael
authors.initials: M
authors.lastname: Callanan
authors.forename: Rob
authors.initials: R
authors.lastname: Edwards
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Fitzgerald
authors.forename: Aidan
authors.initials: A
authors.lastname: Coffey
authors.forename: R Paul
authors.initials: RP
authors.lastname: Ross
mesh_terms: D001435:Bacteriophages / Q000145:classification / Q000235:genetics*; D015254:DNA Modification Methylases / Q000235:genetics; D004720:Endonucleases / Q000235:genetics; D016679:Genome, Viral / Q000235:genetics*; D013294:Lactococcus lactis / Q000235:genetics / Q000821:virology*; D016366:Open Reading Frames / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000379:methods; D012689:Sequence Homology, Nucleic Acid; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D015254:DNA Modification Methylases; D004720:Endonucleases