Identification of substrates and chaperone from the Yersinia enterocolitica 1B Ysa type III secretion system.
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.
Foultier
Boris
B
Microbial Pathogenesis Unit, Christian de Duve Institute of Cellular Pathology, Faculté de Médecine, Université Catholique de Louvain, B1200 Brussels, Belgium.
Troisfontaines
Paul
P
Vertommen
Didier
D
Marenne
Marie-Noëlle
MN
Rider
Mark
M
Parsot
Claude
C
Cornelis
Guy R
GR
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
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D018832:Molecular Chaperones