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A novel bacteriophage Tail-Associated Muralytic Enzyme (TAME) from Phage K and its development into a potent antistaphylococcal protein

DOI: 10.1186/1471-2180-11-226

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Abstract:

We identified a phage K gene, designated orf56, as encoding the phage tail-associated muralytic enzyme (TAME). The gene product (ORF56) contains a C-terminal domain corresponding to cysteine, histidine-dependent amidohydrolase/peptidase (CHAP), which demonstrated muralytic activity on a staphylococcal cell wall substrate and was lethal to S. aureus cells. We constructed N-terminal truncated forms of ORF56 and arrived at a 16-kDa protein (Lys16) that retained antistaphylococcal activity. We then generated a chimeric gene construct encoding Lys16 and a staphylococcal cell wall-binding SH3b domain. This chimeric protein (P128) showed potent antistaphylococcal activity on global clinical isolates of S. aureus including methicillin-resistant strains. In addition, P128 was effective in decolonizing rat nares of S. aureus USA300 in an experimental model.We identified a phage K gene that encodes a protein associated with the phage tail structure. The muralytic activity of the phage K TAME was localized to the C-terminal CHAP domain. This potent antistaphylococcal TAME was combined with an efficient Staphylococcus-specific cell-wall targeting domain SH3b, resulting in the chimeric protein P128. This protein shows bactericidal activity against globally prevalent antibiotic resistant clinical isolates of S. aureus and against the genus Staphylococcus in general. In vivo, P128 was efficacious against methicillin-resistant S. aureus in a rat nasal colonization model.Peptidoglycan-degrading enzymes or murein hydrolases have the ability to digest bacterial cell walls. Such enzymes from bacteriophages represent a unique class of antibacterial agents because of their ability to cleave bacterial peptidoglycan in a species-specific or genus-specific manner. Thus, they provide a means to selectively target pathogens [1-3].At the end of the bacteriophage infection process, progeny are released from the host cell by lysis, which is mediated by two phage-encoded gene products, endolysins

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