THE OUTER-MEMBRANE COMPONENT, YSCC, OF THE YOP SECRETION MACHINERY OFYERSINIA-ENTEROCOLITICA FORMS A RING-SHAPED MULTIMERIC COMPLEX

The YscC protein of Yersinia enterocolifica is essential for the secre tion of anti-host factors, called Yops, into the extracellular environ ment, It belongs to a family of outer membrane proteins, collectively designated secretins, that participate in a variety of transport proce sses, YscC has been shown to exist as a stable oligomeric complex in t he outer membrane. The production of the YscC complex is regulated by temperature and is reduced in strains carrying mutations in the yscN-U operon or in the virG gene. The VirG lipoprotein was shown to be requ ired for efficient targeting of the complex to the outer membrane, Ele ctron microscopy revealed that purified YscC complexes form ring-shape d structures of approximate to 20 nm with an apparent central pore. Be cause of the architecture of the multimer, YscC appears to represent a novel type of channel-forming proteins in the bacterial outer membran e.