Enterohaemorrhagic Escherichia coli haemolysin is cleaved and inactivated by serine protease EspPα.
Bottom Line: In a cellular infection system, the cytolytic potential of EHEC-Hly-secreting recombinant strains was abolished when EspPα was coexpressed.We propose the concept of bacterial effector molecule interference (BEMI), reflecting the concerted interplay of virulence factors.Interference between effector molecules might be an additional way to regulate virulence functions and increases the complexity of monomolecular phenotypes.
Affiliation: Institute of Food Chemistry, University of Münster, Corrensstrasse 45, Münster, Germany. email@example.comShow MeSH
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Mentions: In a first approach, we supplemented an early log-phase culture of clone TA48 producing recombinant EHEC-Hly from EHEC O157 : H7 with 5 µg ml−1 purified, recombinant EspPα from EHEC O157 : H7 or with an EspPα-buffer control (Table 2, panel A-O157 : H7-I) and continued incubation at 37°C for 2 h. Immunoblot analysis of trichloroacetic acid (TCA)-precipitated sterile supernatants using anti-EHEC-Hly polyclonal antibody demonstrated the occurrence of two immunoreactive breakdown products with relative molecular masses (Mr) of 84 ± 4 kDa and 34 ± 3 kDa in TA48 treated with EspPα (Fig. 1A, lane 2). These fragments were not present in TA48 supernatant treated with EspPα-buffer control (Fig. 1A, lane 1), indicating proteolytic cleavage of the 107 kDa large EHEC-Hly by EspPα. EspPα remained unaffected by EHEC-Hly as determined by immunoblot using an anti-EspP antibody. In addition, EspPα did not cross-react with the anti-EHEC-Hly antibody (data not shown).
Affiliation: Institute of Food Chemistry, University of Münster, Corrensstrasse 45, Münster, Germany. firstname.lastname@example.org