Crystal Structure of BnSP-7, a Lys49-PLA2 Complexed with Vitamin E

Daniela P. Marchi-Salvador¹, Agnes A.S., Takeda¹, Andreimar M. Soares², and Marcos R.M. Fontes¹

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

Phospholipases A2 (PLA2) are common components of Bothrops venoms responsible for disruption of cell membrane integrity via hydrolysis of its phospholipids, culminating with cell death. A class of PLA2-like proteins has been described which despite PLA2 activity on artificial substrate, due to a D49K mutation, is still highly myonecrotic and can show a broad spectrum of pharmacological effects, such as: neurotoxicity, cardiotoxicity and may effect anticoagulation, hypotension, platelet aggregation, and inflammatory response. BnSP-7 is a basic Lys49-PLA2 catalytically inactive on artificial substrates, but it shows many biological effects including myotoxicity, and edema inducing and liposome disrupting activity. Recently, the crystal structure of native BnSP-7 has been solved (Magro et al, 2003). a-tocopherol (vitamin E) is a possible candidate against inflammation because it inhibits PLA2 specifically and effectively. Vitamin E is believed to decrease the progression of Alzheimer’s disease by acting as a competitive inhibitor of PLA2s. X-ray diffraction data of a single BnSP-7 crystal were collect (at 100K) using a Synchrotron Radiation Source (LNLS, Campinas). Data were processed at 2.2 Å resolution with a space group P3121 and cell constants a=b=56.2 and c=127.9 Å. The crystal structure was phased using molecular replacement techniques since the crystal is not isomorphous with the native. The vitamin E molecule is bound at active site with His48.

Supported by FAPESP, LNLS and CNPq.

Correspondence to: marchi@ibb.unesp.br or fontes@ibb.unesp.br