title: Friend or foe? Turning a host defense protein into a pathogen's accomplice.
abstract: Cystatins are cysteine protease inhibitors that are at the front-line of defense against pathogens that secrete proteases as virulence factors. In this issue, Vincents et al. (2008) reveal how the bacterial protease IdeS from Streptococcus pyogenes hijacks normal cystatin C function to convert it into a cofactor that enhances proteolytic destruction of host-defense antibodies.
authors.affiliation: Department of Pathology and Microbiology and Immunology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA.
authors.forename: Aimee
authors.initials: A
authors.lastname: Shen
authors.forename: Matthew
authors.initials: M
authors.lastname: Bogyo
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D055316:Cystatin C; D015891:Cystatins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D007074:Immunoglobulin G; C442815:Mac-1-like protein, Streptococcus