title: YscP and YscU regulate substrate specificity of the Yersinia type III secretion system.
abstract: Pathogenic Yersinia species use a type III secretion system to inhibit phagocytosis by eukaryotic cells. At 37 degrees C, the secretion system is assembled, forming a needle-like structure on the bacterial cell surface. Upon eukaryotic cell contact, six effector proteins, called Yops, are translocated into the eukaryotic cell cytosol. Here, we show that a yscP mutant exports an increased amount of the needle component YscF to the bacterial cell surface but is unable to efficiently secrete effector Yops. Mutations in the cytoplasmic domain of the inner membrane protein YscU suppress the yscP phenotype by reducing the level of YscF secretion and increasing the level of Yop secretion. These results suggest that YscP and YscU coordinately regulate the substrate specificity of the Yersinia type III secretion system. Furthermore, we show that YscP and YscU act upstream of the cell contact sensor YopN as well as the inner gatekeeper LcrG in the pathway of substrate export regulation. These results further strengthen the strong evolutionary link between flagellar biosynthesis and type III synthesis.
authors.affiliation: Department of Molecular Biology, Umeå University, S-90187 Umeå, Sweden.
authors.forename: Petra J
authors.initials: PJ
authors.lastname: Edqvist
authors.forename: Jan
authors.initials: J
authors.lastname: Olsson
authors.forename: Moa
authors.initials: M
authors.lastname: Lavander
authors.forename: Lena
authors.initials: L
authors.lastname: Sundberg
authors.forename: Ake
authors.initials: A
authors.lastname: Forsberg
authors.forename: Hans
authors.initials: H
authors.lastname: Wolf-Watz
authors.forename: Scott A
authors.initials: SA
authors.lastname: Lloyd
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D052899:Pore Forming Cytotoxic Proteins; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity / Q000502:physiology; D014774:Virulence / Q000502:physiology; D037521:Virulence Factors; D015007:Yersinia / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C088009:LcrG protein, Yersinia; D008565:Membrane Proteins; D052899:Pore Forming Cytotoxic Proteins; D037521:Virulence Factors; C118802:Yop proteins translocation protein P, Yersinia; C078909:YopB protein, Yersinia; C078910:YopD protein, Yersinia; C070015:YopN protein, Yersinia; C074427:lcrQ protein, Yersinia pseudotuberculosis