Topological dynamics of holins in programmed bacterial lysis.

ABSTRACT: The fate of phage-infected bacteria is determined by the holin, a small membrane protein that triggers to disrupt the membrane at a programmed time, allowing a lysozyme to attack the cell wall. S(21)68, the holin of phage 21, has two transmembrane domains (TMDs) with a predicted N-in, C-in topology. Surprisingly, TMD1 of S(21)68 was found to be dispensable for function, to behave as a SAR ("signal-anchor-release") domain in exiting the membrane to the periplasm, and to engage in homotypic interactions in the soluble phase. The departure of TMD1 from the bilayer coincides with the lethal triggering of the holin and is accelerated by membrane depolarization. Basic residues added at the N terminus of S(21)68 prevent the escape of TMD1 to the periplasm and block hole formation by TMD2. Lysis t

SUBMITTER: Park T 

PROVIDER: S-EPMC1750887 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature