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Activation and mechanism of Clostridium septicum alpha toxin
Author(s) -
Ballard J.,
Sokolov Y.,
Yuan W.L.,
Kagan B. L.,
Tweten R. K.
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb00934.x
Subject(s) - clostridium septicum , biology , mechanism (biology) , toxin , microbiology and biotechnology , clostridium , microbial toxins , alpha (finance) , bacteria , genetics , physics , medicine , construct validity , nursing , quantum mechanics , patient satisfaction
Summary Clostridium septicum produces a single lethal factor, alpha toxin (AT), which is a cytolytic protein with a molecular mass of approximately 48kDa. The 48kDa toxin was found to be an inactive protoxin (AT pro ) which could be activated via a carboxy‐terminal cleavage with trypsin. The cleavage site was located approximately 4kDa from the carboxy‐terminus. Proteolytically activated AT pro had a specific activity of approximately 1.5 × 10 6 haemolytic units mg ‐1 . The trypsin‐activated toxin (AT act ) was haemolytic, stimulated a prelytic release of potassium ions from erythrocytes which was followed by haemoglobin release, induced channel formation in planar membranes and aggregated into a complex of M r >210000 on erythrocyte membranes. AT pro did not exhibit these properties. AT act formed pores with a diameter of at least 1.3‐1.6 nm. We suggest that pore formation on target cell membranes is responsible for the cytolytic activity of alpha toxin.