Identification and characterization of the phage gene sav, involved in sensitivity to the lactococcal abortive infection mechanism AbiV

Appl Environ Microbiol. 2009 Apr;75(8):2484-94. doi: 10.1128/AEM.02093-08. Epub 2009 Mar 6.

Abstract

Lactococcus lactis phage mutants that are insensitive to the recently characterized abortive infection mechanism AbiV were isolated and analyzed in an effort to elucidate factors involved in the sensitivity to AbiV. Whole-genome sequencing of the phage mutants p2.1 and p2.2 revealed mutations in an orf that is transcribed early, indicating that this orf was responsible for AbiV sensitivity. Sequencing of the homologous regions in the genomes of other AbiV-insensitive mutants derived from p2 and six other lactococcal wild-type phages revealed point mutations in the homologous orf sequences. The orf was named sav (for sensitivity to AbiV), and the encoded polypeptide was named SaV. The purification of a His-tagged SaV polypeptide by gel filtration suggested that the polypeptide formed a dimer in its native form. The overexpression of SaV in L. lactis and Escherichia coli led to a rapid toxic effect. Conserved, evolutionarily related regions in SaV polypeptides of different phage groups are likely to be responsible for the AbiV-sensitive phenotype and the toxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriophages / genetics*
  • Bacteriophages / isolation & purification*
  • Chromatography, Gel
  • Cloning, Molecular
  • DNA, Viral / chemistry
  • DNA, Viral / genetics
  • Dimerization
  • Escherichia coli / genetics
  • Genes, Viral*
  • Genome, Viral
  • Lactococcus lactis / virology*
  • Molecular Sequence Data
  • Mutation, Missense*
  • Sequence Analysis, DNA
  • Viral Proteins / genetics
  • Viral Proteins / isolation & purification
  • Viral Proteins / toxicity

Substances

  • DNA, Viral
  • Viral Proteins

Associated data

  • GENBANK/FJ010786