title: Btc22  chaperone is required for secretion and stability of the type III secreted protein  Bsp22  in  Bordetella bronchiseptica.
abstract: The type III secretion system (T3SS) is a sophisticated protein secretion machinery that delivers bacterial virulence proteins into host cells. A needle-tip protein, Bsp22 , is one of the secreted substrates of the T3SS and plays an essential role in the full function of the T3SS in Bordetella bronchiseptica. In this study, we found that BB1618 functions as a chaperone for Bsp22 . The deletion of BB1618 resulted in a dramatic impairment of Bsp22 secretion into the culture supernatants and Bsp22 stability in the bacterial cytosol. In contrast, the secretion of other type III secreted proteins was not affected by the BB1618 mutation. Furthermore, the BB1618 mutant strain could not induce cytotoxicity and displayed the same phenotypes as the Bsp22 mutant strain. An immunoprecipitation assay demonstrated that BB1618 interacts with Bsp22 , but not with BopB and BopD . Thus, we identified BB1618 as a specific type III chaperone for Bsp22 . Therefore, we propose that BB1618 be renamed Btc22 for the Bordetella type III chaperone for Bsp22 .
authors.affiliation: Laboratory of Bacterial Infection, Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kurushima
authors.forename: Asaomi
authors.initials: A
authors.lastname: Kuwae
authors.forename: Akio
authors.initials: A
authors.lastname: Abe
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000502:physiology*; D016950:Bordetella bronchiseptica / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity*; D002460:Cell Line; D004912:Erythrocytes / Q000382:microbiology; D006367:HeLa Cells; D006461:Hemolysis; D006801:Humans; D047468:Immunoprecipitation; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D011817:Rabbits; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D018832:Molecular Chaperones