title: Identification of a third EspA-binding protein that forms part of the type III secretion system of enterohemorrhagic Escherichia coli.
abstract: Enterohemorrhagic Escherichia coli utilizes a type III secretion system to deliver virulent effectors into cells. The secretion apparatus comprises a membrane basal body and an external needle complex of which EspA is the major component. An l0050-deletion (DeltaL50) mutation was found to impair type III secretion and bacterial adherence. These phenotypes and the localization of the gene product to the inner membrane support the hypothesis that L0050, renamed EscL, forms part of the secretion apparatus. Furthermore, in DeltaL50, the amount of EspA present within the cell lysate was found to have diminished, whereas the EspA co-cistron-expressed partner protein EspB remained unaffected. The decreased EspA level appeared to result from instability of the newly synthesized EspA protein in DeltaL50 rather than a decrease in EspA mRNA. Using both biochemical co-purification and a bacterial two-hybrid interaction system, we were able to conclude that EscL is a third protein that, in addition to CesAB and CesA2, interacts with EspA and enhances the stability of intracellular EspA.
authors.affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Beitou, Taipei, 112, Taiwan.
authors.forename: Chen-Peng
authors.initials: CP
authors.lastname: Ku
authors.forename: Joaquim Chan-Wang
authors.initials: JC
authors.lastname: Lio
authors.forename: Shao-Hung
authors.initials: SH
authors.lastname: Wang
authors.forename: Chin-Nan
authors.initials: CN
authors.lastname: Lin
authors.forename: Wan-Jr
authors.initials: WJ
authors.lastname: Syu
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; C496934:Cesa protein, E coli; C087863:EaeB protein, E coli; D029968:Escherichia coli Proteins; C102051:EspA protein, E coli; D018832:Molecular Chaperones; D012329:RNA, Bacterial; D012333:RNA, Messenger; D037521:Virulence Factors