Yersinia pestis YscG protein is a Syc-like chaperone that directly binds YscE

Pathogenic Yersinia species secrete virulence proteins, termed Yersinia out er proteins (Yops), upon contact with a eukaryotic cell. The secretion mach inery is composed of 21 Yersinia secretion (Ysc) proteins. Yersinia pestis mutants defective in expression of YscG or YscE were unable to export the Y ops. YscG showed structural and limited amino-acid-sequence similarities to members of the specific Yop chaperone (Syc) family of proteins. YscG speci fically recognized and bound YscE; however, unlike previously characterized Syc substrates, YscE was not exported from the cell. These data suggest th at YscG functions as a chaperone for YscE.