The interaction of bothropstoxin-I (Lys49-PLA(2)) with liposome membranes

Author(s)

Ferreira, Tatiana Lopes ^[1] ; Ward, Richard J. ^[2]

Affiliation

^[1] Univ Sao Paulo, Dept Bioquim & Imunol, Fac Med Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Dept Quim, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: Toxicon; v. 54, n. 4, p. 525-530, SEP 15 2009.
• Web of Science Citations: 2

Abstract

Bothropstoxin-I (BthTx-I) is a Lys49-PLA(2) from the venom of the snake Bothrops jararacussu, which permeabilizes biological and artificial membranes by a mechanism independent of lipid hydrolysis. This mechanism has been investigated by studying the interaction of nine single tryptophan BthTx-I mutants with negatively charged phospholipid membranes. Changes in the solvent exposure of the tryptophan in each mutant were evaluated comparing the rate of chemical modification (k(mod)) by bromosuccinamide with the maximum intrinsic tryptophan fluorescence emission wavelength (lambda(max)) in buffer and in the presence of 10% DMPA/90% DPPC liposomes. No changes in lambda(max). were observed, whereas k(mod) values for tryptophans at positions 7, 10, 31 and 125 were significantly reduced in the presence of lipids, suggesting that bound phospholipid decreases solvent accessibility at these positions. Since the half-lives of the fluorescence and chemical modification effects differ by at least six orders of magnitude, these results suggest that the bound phospholipid may interact with multiple locations on the protein surface over micro- to millisecond timescales. (C) 2009 Elsevier Ltd. All rights reserved. (AU)