title: Aeromonas salmonicida Ati2 is an effector protein of the type three secretion system.
abstract: The bacterium Aeromonas salmonicida, a fish pathogen, uses the type three secretion system (TTSS) to inject effector proteins into host cells to promote the infection. The study of the genome of A. salmonicida has revealed the existence of Ati2, a potential TTSS effector protein. In the present study, a structure-function analysis of Ati2 has been done to determine its role in the virulence of A. salmonicida. Biochemical assays revealed that Ati2 is secreted into the medium in a TTSS-dependent manner. Protein sequence analyses, molecular modelling and biochemical assays demonstrated that Ati2 is an inositol polyphosphate 5-phosphatase, which hydrolyses PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in a way similar to VPA0450, a protein from Vibrio parahaemolyticus having high sequence similarity with Ati2. Mutants of Ati2 with altered amino acids at two different locations in the catalytic site displayed no phosphatase activity. Wild-type and mutant forms of Ati2 were cloned into expression systems for Dictyostelium discoideum, a soil amoeba used as an alternative host to study A. salmonicida virulence. Expression tests allowed us to demonstrate that Ati2 is toxic for the host cell in a catalytic-dependent manner. Finally, this study demonstrated the existence of a new TTSS effector protein in A. salmonicida.
authors.affiliation: Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, Quebec G1V 4G5, Canada.|Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.|Institut de biologie intégrative et des systèmes, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Dallaire-Dufresne
authors.affiliation: Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.|Institut de biologie intégrative et des systèmes, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Xavier
authors.initials: X
authors.lastname: Barbeau
authors.affiliation: Aquatic and Crop Resource Development, National Research Council Canada, Halifax, Nova Scotia B3H 3Z1, Canada.
authors.forename: Darren
authors.initials: D
authors.lastname: Sarty
authors.affiliation: Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, Quebec G1V 4G5, Canada.|Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.|Institut de biologie intégrative et des systèmes, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Tanaka
authors.affiliation: Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, Quebec G1V 4G5, Canada.|Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.|Institut de biologie intégrative et des systèmes, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Alix M
authors.initials: AM
authors.lastname: Denoncourt
authors.affiliation: Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.|Institut de biologie intégrative et des systèmes, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Lagüe
authors.affiliation: Aquatic and Crop Resource Development, National Research Council Canada, Halifax, Nova Scotia B3H 3Z1, Canada.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Reith
authors.affiliation: Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, Quebec G1V 4G5, Canada.|Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.|Institut de biologie intégrative et des systèmes, Faculté des sciences et de génie, Université Laval, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Charette
mesh_terms: D048409:Aeromonas salmonicida / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D000072181:Inositol Polyphosphate 5-Phosphatases; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases