Crystal Structure of an Acidic PhospholipaseA2 from B. jararacussu at 1.9 Å Resolution

Marcos R. M. Fontes¹, Ângelo J. Magro¹, Sílvia H. Andrião-Escarso² and Andreimar M. Soares².

1 Dep. de Física e Biofísica, Inst. de Biociências, UNESP - Botucatu, SP; 2 Dep. de Biotecnologia, UNAERP, Ribeirão Preto-SP.

Phospholipases A2 belong to the superfamily of proteins which hydrolyzes the sn-2 ester bond of 3-sn membrane phospholipids to release arachidonic acid and lysophospholipids. Recently, we have reported the isolation, biochemical and pharmacological characterization, crystallization and X-ray data collection of an acid PLA2 from B. jararacussu (BthA-I). BthA-I is 3 to 4 times more active catalytically than BthTX-II and other basic Asp49 PLA2 from Bothropsvenoms, however it is not myotoxic, cytotoxic or lethal. Although it showed no toxic activity, it was able to induce time-independent edema, with the activity being inhibited by EDTA. In addition, BthA-I-PLA2 caused a hypotensive response in the rat and inhibited platelet aggregation. Here, we described the crystal structure of dimeric BthA-I. Crystals of BthA-I were obtained by the hanging drop vapor diffusion method using 0.2 M ammonium sulphate and 22% (w/v) polyethylene glycol 6000. X-ray diffraction data were collected (LNLS, Campinas) and data set is 93.3 % complete at 1.9 Å resolution. The crystals belong to the space group P21. The structure was solved by molecular replacement method and refined with the program CNS. The current R and R_free factors are 20.7 and 26.6 %, respectively. The structure presents an unusual dimeric conformation.

Supported by FAPESP, LNLS and CNPq. 

Correspondence to: fontes@ibb.unesp.br