title: Identification of substrates and chaperone from the Yersinia enterocolitica 1B Ysa type III secretion system.
abstract: All pathogenic Yersinia enterocolitica strains carry the pYV plasmid encoding the Ysc-Yop type III secretion (TTS) system, which operates at 37 degrees C. In addition, biovar 1B Y. enterocolitica strains possess a second, chromosomally encoded, TTS system called Ysa, which operates, at least in vitro, under low-temperature and high-salt (LTHS) conditions. Six open reading frames, sycB, yspB, yspC, yspD, yspA, and acpY, neighbor the ysa genes encoding the Ysa TTS apparatus. Here we show that YspA, YspB, YspC, and YspD are secreted by the Ysa TTS system under LTHS conditions. SycB is a chaperone for YspB and YspC and stabilizes YspB. YspB, YspC, and SycB share some similarity with TTS substrates and the chaperone encoded by the Mxi-Spa locus of Shigella flexneri and SPI-1 of Salmonella enterica. In addition, Ysa also secretes the pYV-encoded YopE under LTHS conditions, indicating that YopE is a potential effector of both Y. enterocolitica TTS systems. YspC could also be secreted by S. flexneri, but no functional complementation of ipaC was observed, which indicates that despite their similarity the Ysa and the Mxi-Spa systems are not interchangeable. When expressed from the yopE promoter, YspB and YspC could also be secreted via the Ysc injectisome. However, they could not form detectable pores in eukaryotic target cells and could not substitute for YopB and YopD for translocation of Yop effectors.
authors.affiliation: Microbial Pathogenesis Unit, Christian de Duve Institute of Cellular Pathology, Faculté de Médecine, Université Catholique de Louvain, B1200 Brussels, Belgium.
authors.forename: Boris
authors.initials: B
authors.lastname: Foultier
authors.forename: Paul
authors.initials: P
authors.lastname: Troisfontaines
authors.forename: Didier
authors.initials: D
authors.lastname: Vertommen
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Marenne
authors.forename: Mark
authors.initials: M
authors.lastname: Rider
authors.forename: Claude
authors.initials: C
authors.lastname: Parsot
authors.forename: Guy R
authors.initials: GR
authors.lastname: Cornelis
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D002876:Chromosomes, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D008264:Macrophages; D051379:Mice; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D015008:Yersinia enterocolitica / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D018832:Molecular Chaperones