title: A novel bacteriophage Tail-Associated Muralytic Enzyme (TAME) from Phage K and its development into a potent antistaphylococcal protein.
abstract: BACKGROUND
  Staphylococcus aureus is a major cause of nosocomial and community-acquired infections. However, the rapid emergence of antibiotic resistance limits the choice of therapeutic options for treating infections caused by this organism. Muralytic enzymes from bacteriophages have recently gained attention for their potential as antibacterial agents against antibiotic-resistant gram-positive organisms. Phage K is a polyvalent virulent phage of the Myoviridae family that is active against many Staphylococcus species.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Gangagen Biotechnologies Pvt Ltd, Raghavendra Layout, Tumkur Road, Yeshwantpur, Bangalore 560022, India.
authors: Vivek Daniel
authors: VD
authors: Paul
authors: Sanjeev Saravanan
authors: SS
authors: Rajagopalan
authors: Sudarson
authors: S
authors: Sundarrajan
authors: Shilpa E
authors: SE
authors: George
authors: Jiya Y
authors: JY
authors: Asrani
authors: Renjith
authors: R
authors: Pillai
authors: Ravisha
authors: R
authors: Chikkamadaiah
authors: Murali
authors: M
authors: Durgaiah
authors: Bharathi
authors: B
authors: Sriram
authors: Sriram
authors: S
authors: Padmanabhan
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D006801:Humans; D017900:Myoviridae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects / Q000502:physiology; D013204:Staphylococcus Phages / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D017376:Viral Tail Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D017376:Viral Tail Proteins; D000581:Amidohydrolases