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- Title
Release of the type I secreted α-haemolysin via outer membrane vesicles from Escherichia coli.
- Authors
Balsalobre, Carlos; Silván, Jose Manuel; Berglund, Stina; Mizunoe, Yoshimitsu; Uhlin, Bernt Eric; Wai, Sun Nyunt
- Abstract
The α-haemolysin is an important virulence factor commonly expressed by extraintestinal pathogenic Escherichia coli. The secretion of the α-haemolysin is mediated by the type I secretion system and the toxin reaches the extracellular space without the formation of periplasmic intermediates presumably in a soluble form. Surprisingly, we found that a fraction of this type I secreted protein is located within outer membrane vesicles (OMVs) that are released by the bacteria. The α-haemolysin appeared very tightly associated with the OMVs as judged by dissociation assays and proteinase susceptibility tests. The α-haemolysin in OMVs was cytotoxically active and caused lysis of red blood cells. The OMVs containing the α-haemolysin were distinct from the OMVs not containing α-haemolysin, showing a lower density. Furthermore, they differed in protein composition and one component of the type I secretion system, the TolC protein, was found in the lower density vesicles. Studies of natural isolates of E. coli demonstrated that the localization of α-haemolysin in OMVs is a common feature among haemolytic strains. We propose an alternative pathway for the transport of the type I secreted α-haemolysin from the bacteria to the host cells during bacterial infections.
- Subjects
RESEARCH; ESCHERICHIA coli; ESCHERICHIA; MICROBIAL virulence; PATHOGENIC bacteria; BACTERIA; ERYTHROCYTES; BLOOD cells; PROTEINS; BACTERIAL diseases
- Publication
Molecular Microbiology, 2006, Vol 59, Issue 1, p99
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.2005.04938.x