Tail-associated structural protein gp61 ofStaphylococcus aureusphage φMR11 has bifunctional lytic activity

Abstract

A tailed bacteriophage, phi MR11 (siphovirus), was selected as a candidate therapeutic phage against Staphylococcus aureus infections. Gene 61, one of the 67 ORFs identified, is located in the morphogenic module. The gene product (gp61) has lytic domains homologous to CHAP (corresponding to an amidase function) at its N-terminus and lysozyme subfamily 2 (LYZ2) at its C-terminus. Each domain of gp61 was purified as a recombinant protein. Both the amidase [amino acids (aa) 1-150] and the lysozyme (aa 401-624) domains but not the linker domain (aa 151-400) caused efficient lysis of S. aureus. Immunoelectron microscopy localized gp61 to the tail tip of the phi MR11 phage. These data strongly suggest that gp61 is a tail-associated lytic factor involved in local cell-wall degradation, allowing the subsequent injection of phi MR11 DNA into the host cytoplasm. Staphylococcus aureus lysogenized with phi MR11 was also lysed by both proteins. Staphylococcus aureus strains on which phi MR11 phage can only produce spots but not plaques were also lysed by each protein, indicating that gp61 may be involved in 'lysis from without'. This is the first report of the presence of a tail-associated virion protein that acts as a lysin, in an S. aureus phage.

Genome, Integration, and Transduction of a Novel Temperate Phage of Helicobacter pylori

“…These results suggest that the failure of 1961P to form plaques on most strains of H. pylori strains is not due to prophage-induced immunity. Rather, this situation may be similar to that of Staphylococcus aureus phage MR11, in which unknown muralytic enzymes associated with structural proteins of the phage are believed to inhibit plaque formation (36).…”

Characterization of Novel Phages Isolated in Coagulase-Negative Staphylococci Reveals Evolutionary Relationships with Staphylococcus aureus Phages

“…These proteins are related to the well-characterized and highly conserved tailassociated GP61 protein of the staphylococcal phage phiMR11. GP61 is thought to be involved in cell host lysis during phage adsorption (13,14,53,62). The GP61 homolog in StB12 is encoded by the three successive ORF64, ORF65, and ORF66 that are interrupted by two putative group I introns at positions 37063 to 37307 and 37542 to 37918.…”

The Tape Measure Protein of the Staphylococcus aureus Bacteriophage vB_SauS-phiIPLA35 Has an Active Muramidase Domain

“…However, the presence in phages phiIPLA88 and phiMR11 of proteins with muralytic activities might indicate its involvement in local cell wall degradation, allowing the subsequent introduction of DNA into the host cytoplasm (13,14). In phiIPLA35, the presence of an active muramidase domain in the TMP could also indicate its contribution to the infection process, taking into account that no other virion-associated proteins with peptidoglycan hydrolase activity were identified in this phage (8).…”