Papers by Luca Monticelli
Biophysical Journal, 2011
The primary function of secreted Phospholipase A2 (sPLA2) is to catalyze the hydrolysis of the sn... more The primary function of secreted Phospholipase A2 (sPLA2) is to catalyze the hydrolysis of the sn-2 ester bond of phospholipids. The interaction of sPLA2 with phospholipid membranes has been considered to be a basic mechanism for the biological function of the protein. Despite a wealth of experimental data available, the conformational and energetic changes of these proteins during the adsorption process remain poorly understood. In this study, the interaction of sPLA2 with the lipid bilayer was investigated by MD simulations using an implicit membrane model (IMM1). The principal goal of this work is to identify the molecular determinants on PLA2 surface that are required for interfacial binding, and to characterize the conformational changes associated with the activation of enzyme. In 50ns MD simulations, starting from six different initial positions of the protein, sPLA2 consistently adopts an orientation with respect to the membrane, in very close agreement with the known EPR data. Our simulations have also predicted the experimentally obtained distribution of polar and hydrophobic residues on the interfacial binding surface. The association of sPLA2 with membrane is accompanied by conformational changes in the secondary structure of the protein. The most important change includes the movement of the N-terminal helix towards the calcium binding loop. The hydroxyl of the active site Tyr52, along with catalytic Asp49 residue, participates in a hydrogen-bonding network that connects the catalytic site to the N-terminal region on the enzyme surface. The determinants of substrate specificity are explored by investigating the energetic consequences of phospholipid binding and conformational changes in the active site during the binding process to anionic membrane.
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Papers by Luca Monticelli