1olp
ALPHA TOXIN FROM CLOSTRIDIUM ABSONUM
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OverviewOverview
Clostridium absonum phospholipase C (Caa) is a 42.7 kDa protein, which, shows 60% amino acid sequence identity with the Clostridium perfringens, phospholipase C, or alpha-toxin (Cpa), and has been isolated from patients, suffering from gas gangrene. We report the cloning and sequencing, purification, characterisation and crystal structure of the Caa enzyme., Caa had twice the phospholipid-hydrolysing (lecithinase) activity, 1.5, times the haemolytic activity and over seven times the activity towards, phosphatidylcholine-based liposomes when compared with Cpa. However, the, Caa enzyme had a lower activity than Cpa to the free (i.e. not in lipid, bilayer) substrate para-nitrophenylphosphorylcholine, towards, sphingomyelin-based liposomes and showed half the cytotoxicity. The lethal, dose (LD(50)) of Caa in mice was approximately twice that of Cpa. The, crystal structure of Caa shows that the 72-93 residue loop is in a, conformation different from those of previously determined open-form, alpha-toxin structures. This conformational change suggests a role for W84, in membrane binding and a possible route of entry into the active site, along a hydrophobic channel created by the re-arrangement of this loop., Overall, the properties of Caa are compatible with a role as a, virulence-determinant in gas gangrene caused by C.absonum.
About this StructureAbout this Structure
1OLP is a Single protein structure of sequence from Clostridium sardiniense with CA and ZN as ligands. Active as Phospholipase C, with EC number 3.1.4.3 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
Clostridium absonum alpha-toxin: new insights into clostridial phospholipase C substrate binding and specificity., Clark GC, Briggs DC, Karasawa T, Wang X, Cole AR, Maegawa T, Jayasekera PN, Naylor CE, Miller J, Moss DS, Nakamura S, Basak AK, Titball RW, J Mol Biol. 2003 Oct 31;333(4):759-69. PMID:14568535
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