title: EspO1-2 regulates EspM2-mediated RhoA activity to stabilize formation of focal adhesions in enterohemorrhagic Escherichia coli-infected host cells.
abstract: Enterohemorrhagic Escherichia coli (EHEC) Sakai strain encodes two homologous type III effectors, EspO1-1 and EspO1-2. These EspO1s have amino acid sequence homology with Shigella OspE, which targets integrin-linked kinase to stabilize formation of focal adhesions (FAs). Like OspE, EspO1-1 was localized to FAs in EHEC-infected cells, but EspO1-2 was localized in the cytoplasm. An EHEC ΔespO1-1ΔespO1-2 double mutant induced cell rounding and FA loss in most of infected cells, but neither the ΔespO1-1 nor ΔespO1-2 single mutant did. These results suggested that EspO1-2 functioned in the cytoplasm by a different mechanism from EspO1-1 and OspE. Since several type III effectors modulate Rho GTPase, which contributes to FA formation, we investigated whether EspO1-2 modulates the function of these type III effectors. We identified a direct interaction between EspO1-2 and EspM2, which acts as a RhoA guanine nucleotide exchange factor. Upon ectopic co-expression, EspO1-2 co-localized with EspM2 in the cytoplasm and suppressed EspM2-mediated stress fiber formation. Consistent with these findings, an ΔespO1-1ΔespO1-2ΔespM2 triple mutant did not induce cell rounding in epithelial cells. These results indicated that EspO1-2 interacted with EspM2 to regulate EspM2-mediated RhoA activity and stabilize FA formation during EHEC infection.
authors: Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan. ishihara@nih.go.jp
authors: Tomoko
authors: T
authors: Morita-Ishihara
authors: Masashi
authors: M
authors: Miura
authors: Sunao
authors: S
authors: Iyoda
authors: Hidemasa
authors: H
authors: Izumiya
authors: Haruo
authors: H
authors: Watanabe
authors: Makoto
authors: M
authors: Ohnishi
authors: Jun
authors: J
authors: Terajima
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D002460:Cell Line; D048430:Cell Shape; D003593:Cytoplasm / Q000378:metabolism; D054324:Enterohemorrhagic Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022001:Focal Adhesions / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D055550:Protein Stability; D021381:Protein Transport; D016415:Sequence Alignment; D015398:Signal Transduction; D022502:Stress Fibers / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; D029968:Escherichia coli Proteins; C582653:EspO1-2 protein, E coli; D008840:Microfilament Proteins; C543137:espM protein, E coli; D020742:rhoA GTP-Binding Protein