The Holin protein of bacteriophage PRD1 forms a pore for small-molecule and endolysin translocation

J Bacteriol. 2005 Aug;187(15):5397-405. doi: 10.1128/JB.187.15.5397-5405.2005.


PRD1 is a bacteriophage with an icosahedral outer protein layer surrounding the viral membrane, which encloses the linear double-stranded DNA genome. PRD1 infects gram-negative cells harboring a conjugative IncP plasmid. Here we studied the lytic functions of PRD1. Using infected cells and plasmid-borne lysis genes, we demonstrated that a two-component lysis system (holin-endolysin) operates to release progeny phage particles from the host cell. Monitoring of ion fluxes and the ATP content of the infected cells allowed us to build a model of the sequence of lysis-related physiological changes. A decrease in the intracellular level of ATP is the earliest indicator of cell lysis, followed by the leakage of K+ from the cytosol approximately 20 min prior to the decrease in culture turbidity. However, the K+ efflux does not immediately lead to the depolarization of the cytoplasmic membrane or leakage of the intracellular ATP. These effects are observed only approximately 5 to 10 min prior to cell lysis. Similar results were obtained using cells expressing the holin and endolysin genes from plasmids.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriolysis*
  • Bacteriophage PRD1 / genetics
  • Bacteriophage PRD1 / physiology*
  • Cell Membrane / metabolism
  • Cell Membrane Permeability
  • Endopeptidases / genetics
  • Endopeptidases / metabolism*
  • Genes, Viral
  • Genetic Complementation Test
  • Ions / metabolism
  • Onium Compounds
  • Organophosphorus Compounds
  • Potassium / metabolism
  • Salmonella enterica / genetics
  • Salmonella enterica / physiology
  • Salmonella enterica / virology*
  • Viral Proteins / genetics
  • Viral Proteins / physiology*


  • Ions
  • Onium Compounds
  • Organophosphorus Compounds
  • P35 protein, Enterobacteria phage PRD1
  • Viral Proteins
  • Endopeptidases
  • endolysin
  • Potassium
  • tetraphenylphosphonium