KSY1, a lactococcal phage with a T7-like transcription

Virology. 2007 Aug 15;365(1):1-9. doi: 10.1016/j.virol.2007.03.044. Epub 2007 Apr 30.


The virulent lactococcal phage KSY1 possesses a large elongated capsid (223 nm long, 45 nm wide) and a short tail (32 nm). This phage of the Podoviridae group (C3 morphotype) has a linear 79,232-bp double-stranded DNA genome, which encodes 131 putative proteins and 3 tRNAs. This is the first description of the genome of a phage of this morphotype. KSY1 possesses a T7-like transcription system, including an RNA polymerase and a series of specific promoters, showing sequence homology to other known T7-like RNA polymerase promoters. Late stages of KSY1 multiplication are resistant to rifampicin. Otherwise, KSY1 shares limited similarity with other Podoviridae phages. Fourteen KSY1 structural proteins were identified by SDS-PAGE analysis. Among these proteins, those forming the distal tail structure and likely involved in host recognition are encoded by a 5-kb genomic region of KSY1. This region consists of a mosaic of DNA segments highly homologous to DNA of other lactococcal phages, suggesting an horizontal gene transfer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriophage T7 / genetics
  • Genome, Viral*
  • Lactococcus / virology*
  • Molecular Sequence Data
  • Open Reading Frames
  • Podoviridae / classification
  • Podoviridae / enzymology
  • Podoviridae / genetics*
  • Transcription, Genetic
  • Viral Proteins / chemistry


  • Viral Proteins

Associated data

  • GENBANK/DQ535032