1olp: Difference between revisions

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.

1OLP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_sardiniense Clostridium sardiniense] with CA and ZN as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Phospholipase_C Phospholipase C], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.4.3 3.1.4.3] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1OLP OCA].  

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov  5 13:08:28 2007''