title: Regulation of Yersinia Yop-effector delivery by translocated YopE.
abstract: The bacterial pathogen Yersinia pseudotuberculosis uses a type III secretion (T3S) system to translocate Yop effectors into eukaryotic cells. Effectors are thought to gain access to the cytosol via pores formed in the host cell plasma membrane. Translocated YopE can modulate this pore formation through its GTPase-activating protein (GAP) activity. In this study, we analysed the role of translocated YopE and all the other known Yop effectors in the regulation of effector translocation. Elevated levels of Yop effector translocation into HeLa cells occurred by YopE-defective strains, but not those defective for other Yop effectors. Only Yersinia devoid of YopK exhibits a similar hyper-translocation phenotype. Since both yopK and yopE mutants also failed to down-regulate Yop synthesis in the presence of eukaryotic cells, these data imply that translocated YopE specifically regulates subsequent effector translocation by Yersinia through at least one mechanism that involves YopK. We suggest that the GAP activity of YopE might be working as an intra-cellular probe measuring the amount of protein translocated by Yersinia during infection. This may be a general feature of T3S-associated GAP proteins, since two homologues from Pseudomonas aeruginosa, exoenzyme S (ExoS) and exoenzyme T (ExoT), can complement the hyper-translocation phenotypes of the yopE GAP mutant.
authors.affiliation: Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden.
authors.forename: Margareta
authors.initials: M
authors.lastname: Aili
authors.forename: Elin L
authors.initials: EL
authors.lastname: Isaksson
authors.forename: Sara E
authors.initials: SE
authors.lastname: Carlsson
authors.forename: Hans
authors.initials: H
authors.lastname: Wolf-Watz
authors.forename: Roland
authors.initials: R
authors.lastname: Rosqvist
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Francis
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism / Q000494:pharmacology; D001427:Bacterial Toxins / Q000494:pharmacology; D025461:Feedback, Physiological; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009154:Mutation; D021381:Protein Transport / Q000502:physiology*; D014774:Virulence; D015011:Yersinia pseudotuberculosis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D015012:Yersinia pseudotuberculosis Infections / Q000503:physiopathology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D020690:GTPase-Activating Proteins; C063239:yopE protein, Yersinia; D007770:L-Lactate Dehydrogenase; D036002:ADP Ribose Transferases