Salmonella Research Today is a free monthly online journal that collates and summarizes the latest research about Salmonella, including details on salmonella typhimurium, food poisoning, infection, treatment.

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

Ziedaite G, Daugelavicius R, Bamford JK, Bamford DH

Biocenter 2, P.O. Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Finland.

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.

Published 20 July 2005 in J Bacteriol, 187(15): 5397-405.
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