Active cytotoxic necrotizing factor 1 associated with outer membrane vesicles from uropathogenic Escherichia coli.
Cytotoxic necrotizing factor type 1 (CNF1) is one of the virulence factors produced by uropathogenic Escherichia coli (UPEC). How this toxin is translocated from the bacterial cytoplasm to the surrounding environment is not well understood. Our data suggest that CNF1 may be regarded as a secreted protein, since it could be detected in culture supernatants. Furthermore, we found that CNF1 was tightly associated to outer membrane vesicles, suggesting that such vesicles play a role in the secretion of this protein. Interestingly, vesicle samples containing CNF1 could exert the effects known for this protein on HeLa cell cultures, showing that CNF1 is transported by vesicles in its active form. Taken together, our results strongly suggest that outer membrane vesicles could be a means for the bacteria to deliver CNF1 to the environment and to the infected tissue. In addition, our results indicate that the histone-like nucleoid structuring protein H-NS has a role in the downregulation of CNF1 production and that it affects the outer membrane vesicle release in UPEC strain J96.
Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden.
J Clavin
JC
Kouokam
Sun Nyunt
SN
Wai
Maria
M
Fällman
Ulrich
U
Dobrindt
Jörg
J
Hacker
Bernt Eric
BE
Uhlin
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active; D015153:Blotting, Western; D003603:Cytotoxins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D022161:Transport Vesicles / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C116822:hns protein, E coli; C060296:cytotoxic necrotizing factor type 1