Caister Academic Press

Release of Progeny Phages from Infected Cells

Carlos São José, João Nascimento, Ricardo Parreira and Mário A. Santos
from: Bacteriophage: Genetics and Molecular Biology (Edited by: Stephen Mc Grath and Douwe van Sinderen). Caister Academic Press, U.K. (2007)

Abstract

Progeny release from phage-infected cells can occur either by lysis of the host or by a singular secretion mechanism, which has been only documented so far for filamentous phages. All known double stranded DNA phages synthesize two lysis effectors, an endolysin and a holin, the first providing a muralytic function and the second a lysis timing device. Endolysins and holins from different phages can be structurally very diverse in spite of their functional similarities. In its export to the cell wall, the endolysin can either be dependent on holin-formed membrane lesions or use the general secretion pathway of the host. In several known cases an antiholin is also produced. This protein can be either soluble or membrane-bound. In T4, the anti-holin is crucial in the response to superinfecting phage, in a process known as lysis inhibition (LIN). Phage members of the Microviridae and Leviviridae families are also bacteriolytic but use a single gene lysis strategy to release their progeny. The mechanism employed relies on the production of murein synthesis inhibitors and thus lysis by such phages is akin to lysis mediated by antibiotics which target the cell wall. The Inoviridae, filamentous phages, do not lyse their hosts. They are assembled during export, using transmembrane channels formed by at least one inner membrane phage-encoded protein and an outer membrane secretin.

Recommended link: Evergreen Phage Biology

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