Structure and protective efficacy of the Staphylococcus aureus autocleaving protease EpiP.

Abstract

Despite the global medical needs associated with Staphylococcus aureus infections, no licensed vaccines are currently available. We identified and characterized a protein annotated as an epidermin leader peptide processing serine protease (EpiP), as a novel S. aureus vaccine candidate. In addition, we determined the structure of the recombinant protein (rEpiP) by X-ray crystallography. The crystal structure revealed that rEpiP was cleaved somewhere between residues 95 and 100, and we found that the cleavage occurs through an autocatalytic intramolecular mechanism. The protein expressed by S. aureus cells also appeared to undergo a similar processing event. To determine whether the protein acts as a serine protease, we mutated the hypothesized catalytic serine 393 residue to alanine, generating rEpiP-S393A. The crystal structure of this mutant protein showed that the polypeptide chain was not cleaved and was not interacting stably with the active site. Indeed, rEpiP-S393A was shown to be impaired in its protease activity. Mice vaccinated with rEpiP were protected from S. aureus infection (34% survival, P=0.0054). Moreover, the protective efficacy generated by rEpiP and rEpiP-S393A was comparable, implying that the noncleaving mutant could be used for vaccination purposes.

• Authors: Misty L Kuhn, Prachi Prachi, George Minasov, Ludmilla Shuvalova, Jiapeng Ruan, Ievgeniia Dubrovska, James Winsor, Monica Giraldi, Massimiliano Biagini, Sabrina Liberatori, Silvana Savino, Fabio Bagnoli, Wayne F Anderson, Guido Grandi
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 28 Issue 4 Pg. 1780-93 (Apr 2014) ISSN: 1530-6860 [Electronic] United States
• PMID: 24421400 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Bacterial Proteins
• Bacterial Vaccines
• Recombinant Proteins
• EpiP serine protease
• Serine Endopeptidases

Topics

• Animals
• Bacterial Proteins (chemistry, genetics, immunology)
• Bacterial Vaccines (administration & dosage, immunology)
• Biocatalysis
• Blotting, Western
• Catalytic Domain
• Crystallography, X-Ray
• Mice
• Models, Molecular
• Mutation
• Protein Conformation
• Recombinant Proteins (chemistry, immunology, metabolism)
• Serine Endopeptidases (chemistry, genetics, immunology)
• Staphylococcal Infections (immunology, microbiology, prevention & control)
• Staphylococcus aureus (enzymology, genetics, immunology)
• Static Electricity