A peptidoglycan hydrolase motif within the mycobacteriophage TM4 tape measure protein promotes efficient infection of stationary phase cells.

PIURI M,; HATFULL GF

MOLECULAR MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2006 vol. 62 p. 1569 - 1585

0950-382X

The predominant morphotype of mycobacteriophagevirions has a DNA-containing capsid attached to along flexible non-contractile tail, features characteristicof the Siphoviridae. Within these phage genomesthe tape measure protein (tmp) gene can be readilyidentified due to the well-established relationshipbetween the length of the gene and the length of thephage tail – because these phages typically have longtails, the tmp gene is usually the largest gene in thegenome. Many of these mycobacteriophage Tmp’scontain small motifs with sequence similarity to hostproteins. One of these motifs (motif 1) corresponds tothe Rpf proteins that have lysozyme activity and functionto stimulate growth of dormant bacteria, while theothers (motifs 2 and 3) are related to proteins ofunknown function, although some of the related proteinsof the host are predicted to be involved in cellwall catabolism.We show here that motif 3-containingproteins have peptidoglycan-hydrolysing activity andthat while this activity is not required for phage viability,it facilitates efficient infection and DNA injectioninto stationary phase cells. Tmp’s of mycobacteriophagesmay thus have acquired these motifs in order toavoid a selective disadvantage that results fromchanges in peptidoglycan in non-growing cells.