1gyg
From Proteopedia
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R32 CLOSED FORM OF ALPHA-TOXIN FROM CLOSTRIDIUM PERFRINGENS STRAIN CER89L43
Overview
Clostridium perfringens biotype A strains are the causative agents of, gas-gangrene in man and are also implicated as etiological agents in, sudden death syndrome in young domestic livestock. The main virulence, factor produced by these strains is a zinc-dependent, phosphatidylcholine-preferring phospholipase C (alpha-toxin). The crystal, structure of alpha-toxin, at pH 7.5, with the active site open and, therefore accessible to substrate has previously been reported, as has, calcium-binding to the C-terminal domain of the enzyme at pH 4.7. Here we, focus on conformation changes in the N-terminal domain of alpha-toxin in, crystals grown at acidic pH. These changes result in both the obscuring of, the toxin active site and the loss of one of three zinc ions from it., Additionally, this "closed" form contains a small alpha helix, not present, in the open structure, which hydrogen bonds to both the N and C-terminal, domains. In conjunction with the previously reported findings that, alpha-toxin can exist in active and inactive forms and that Thr74Ile and, Phe69Cys substitutions markedly reduced the haemolytic activity of the, enzyme, our work suggests that these loop conformations play a critical, role in the activity of the toxin.
About this Structure
1GYG is a Single protein structure of sequence from Clostridium perfringens with as ligand. Active as Phospholipase C, with EC number 3.1.4.3 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Crystal structure of the C. perfringens alpha-toxin with the active site closed by a flexible loop region., Eaton JT, Naylor CE, Howells AM, Moss DS, Titball RW, Basak AK, J Mol Biol. 2002 May 31;319(2):275-81. PMID:12051905
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