1s8h
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(New page: 200px<br /><applet load="1s8h" size="450" color="white" frame="true" align="right" spinBox="true" caption="1s8h, resolution 1.80Å" /> '''Crystal structure of...)
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Revision as of 00:05, 21 November 2007
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Crystal structure of Lys49-Phospholipase A2 from Agkistrodon contortrix laticinctus, first fatty acid free form
Overview
Agkistrodon contortrix laticinctus myotoxin is a Lys(49)-phospholipase, A(2) (EC 3.1.1.4) isolated from the venom of the serpent A. contortrix, laticinctus (broad-banded copperhead). We present here three monomeric, crystal structures of the myotoxin, obtained under different, crystallization conditions. The three forms present notable structural, differences and reveal that the presence of a ligand in the active site, (naturally presumed to be a fatty acid) induces the exposure of a, hydrophobic surface (the hydrophobic knuckle) toward the C terminus. The, knuckle in A. contortrix laticinctus myotoxin involves the side chains of, Phe(121) and Phe(124) and is a consequence of the formation of a canonical, structure for the main chain within the region of residues 118-125., Comparison with other Lys(49)-phospholipase A(2) myotoxins shows that, although the knuckle is a generic structural motif common to all members, of the family, it is not readily recognizable by simple sequence analyses., An activation mechanism is proposed that relates fatty acid retention at, the active site to conformational changes within the C-terminal region, a, part of the molecule that has long been associated with Ca(2+)-independent, membrane damaging activity and myotoxicity. This provides, for the first, time, a direct structural connection between the phospholipase "active, site" and the C-terminal "myotoxic site," justifying the otherwise, enigmatic conservation of the residues of the former in supposedly, catalytically inactive molecules.
About this Structure
1S8H is a Single protein structure of sequence from Agkistrodon contortrix laticinctus with SO4 as ligand. Active as Phospholipase A(2), with EC number 3.1.1.4 Full crystallographic information is available from OCA.
Reference
A molecular mechanism for Lys49-phospholipase A2 activity based on ligand-induced conformational change., Ambrosio AL, Nonato MC, de Araujo HS, Arni R, Ward RJ, Ownby CL, de Souza DH, Garratt RC, J Biol Chem. 2005 Feb 25;280(8):7326-35. Epub 2004 Dec 13. PMID:15596433
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