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Infect. Immun., 03 1997, 1014-1022, Vol 65, No. 3
JF Kokai-Kun and BA McClane
To further our knowledge of the structure-function relationship and
mechanism of action of the Clostridium perfringens enterotoxin (CPE), a
series of recombinant CPE (rCPE) species containing N- and C-terminal CPE
deletion fragments was constructed by recombinant DNA approaches. Each rCPE
species was characterized for its ability to complete the first four early
steps in the action of CPE, putatively ordered as specific binding, a
postbinding physical change to bound CPE, large- complex formation, and
induction of alterations in small-molecule membrane permeability. These
studies demonstrated that (i) at least 44 amino acids can be removed from
the N terminus of CPE without loss of cytotoxicity, (ii) removal of the
first 53 amino acids from the N terminus of CPE produces a fragment that
appears to be noncytotoxic because it cannot undergo the post-binding
physical change step in CPE action, (iii) removal of as few as five amino
acids from the C terminus of CPE produces a noncytotoxic fragment lacking
receptor binding activity, and (iv) a fragment lacking the first 44
N-terminal amino acids of native CPE formed twice as much large complex and
was twice as cytotoxic as native CPE. From these structure-function
results, it appears that the minimum-size cytotoxic CPE fragment comprises
approximately residues 45 to 319 of native CPE. Results from these deletion
fragment studies have also contributed to our understanding of CPE action
by (i) independently supporting previous suggestions that binding, the
postbinding physical change step, and large-complex formation represent
important steps in CPE cytotoxicity and (ii) providing independent evidence
confirming the putative sequential order of these early events in CPE
action.
Copyright © 1997, American Society for Microbiology
Deletion analysis of the Clostridium perfringens enterotoxin
Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA.
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