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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

A molecular mechanism for Lys(49)-phospholipase A(2) activity based on ligand-induced conformational change

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Autor(es):
Ambrosio, Andre L. B. ; Nonato, M. Cristina ; Araújo, Heloísa S. Selistre de ; Arni, Raghuvir ; Ward, Richard J. ; Ownby, Charlotte L. ; Souza, Dulce H. F. de ; Garratt, Richard C.
Número total de Autores: 8
Tipo de documento: Artigo Científico
Fonte: Journal of Biological Chemistry; v. 280, n. 8, p. 7326-7335, Feb. 2005.
Área do conhecimento: Ciências Biológicas - Farmacologia
Assunto(s):Farmacologia molecular   Antígenos   Venenos de origem animal   Serpentes   Agkistrodon
Resumo

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 Ca2+-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. (AU)

Processo FAPESP: 00/14959-8 - Estudos da interação de ácidos graxos com Lys-49 fosfolipases A2 por difração de raios-x e ressonância magnética nuclear
Beneficiário:Andre Luis Berteli Ambrosio
Linha de fomento: Bolsas no Brasil - Mestrado