Clear Plaque Mutants of Lactococcal Phage TP901-1

PLoS One. 2016 Jun 3;11(6):e0155233. doi: 10.1371/journal.pone.0155233. eCollection 2016.

Abstract

We report a method for obtaining turbid plaques of the lactococcal bacteriophage TP901-1 and its derivative TP901-BC1034. We have further used the method to isolate clear plaque mutants of this phage. Analysis of 8 such mutants that were unable to lysogenize the host included whole genome resequencing. Four of the mutants had different mutations in structural genes with no relation to the genetic switch. However all 8 mutants had a mutation in the cI repressor gene region. Three of these were located in the promoter and Shine-Dalgarno sequences and five in the N-terminal part of the encoded CI protein involved in the DNA binding. The conclusion is that cI is the only gene involved in clear plaque formation i.e. the CI protein is the determining factor for the lysogenic pathway and its maintenance in the lactococcal phage TP901-1.

MeSH terms

  • Bacteriophages / genetics*
  • DNA, Viral*
  • Lactococcus / virology*
  • Mutation*
  • Promoter Regions, Genetic
  • Viral Proteins / genetics*

Substances

  • DNA, Viral
  • Viral Proteins

Grants and funding

This work was supported by the Danish Council for Independent Research (http://ufm.dk/en/research-andinnovation/councils-and-commissions/the-danish-council-for-independent-research) grant 4093-00198 (received by WK), used to cover cost of data generation and analysis; and the Danish Council for Independent Research (http://ufm.dk/en/research-andinnovation/councils-and-commissions/the-danish-council-for-independent-research) grant 0602-02271B (received by FKV), used to cover cost of data generation and analysis. Grant 4002-00107 from Danish Council for Independent Research received by Dr. Leila Lo Leggio, at the Chemical Department, University of Copenhagen is acknowledged for sponsoring materials for cloning and enzyme activity assays. Dr. Leila Lo Leggio had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.