Docking and free energy simulations to predict conformational domains involved in hCG-LH receptor interactions using recombinant antibodies

Majumdar, Ritankar and Railkar, Reema and Dighe, Rajan R (2011) Docking and free energy simulations to predict conformational domains involved in hCG-LH receptor interactions using recombinant antibodies. In: Proteins: Structure, Function, and Genetics, 79 (11). pp. 3108-3122.

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Abstract

Single chain fragment variables (ScFvs) have been extensively employed in studying the protein-protein interactions. ScFvs derived from phage display libraries have an additional advantage of being generated against a native antigen, circumventing loss of information on conformational epitopes. In the present study, an attempt has been made to elucidate human chorionic gonadotropin (hCG)-luteinizing hormone (LH) receptor interactions by using a neutral and two inhibitory ScFvs against hCG. The objective was to dock a computationally derived model of these ScFvs onto the crystal structure of hCG and understand the differential roles of the mapped epitopes in hCG-LH receptor interactions. An anti-hCG ScFv, whose epitope was mapped previously using biochemical tools, served as the positive control for assessing the quality of docking analysis. To evaluate the role of specific side chains at the hCG-ScFv interface, binding free energy as well as residue interaction energies of complexes in solution were calculated using molecular mechanics Poisson-Boltzmann/surface area method after performing the molecular dynamic simulations on the selected hCG-ScFv models and validated using biochemical and SPR analysis. The robustness of these calculations was demonstrated by comparing the theoretically determined binding energies with the experimentally obtained kinetic parameters for hCG-ScFv complexes. Superimposition of hCG-ScFv model onto a model of hCG complexed with the 51-266 residues of LH receptor revealed importance of the residues previously thought to be unimportant for hormone binding and response. This analysis provides an alternate tool for understanding the structure-function analysis of ligand-receptor interactions. Proteins 2011;79:3108-3122. (C) 2011 Wiley-Liss, Inc.

Item Type:	Journal Article
Publication:	Proteins: Structure, Function, and Genetics
Publisher:	John Wiley & Sons
Additional Information:	Copyright of this article belongs to John Wiley & Sons.
Keywords:	glycoprotein hormones;GPCR;phage display;ScFv modeling; residue contact;association-dissociation kinetics;molecular dynamics;MM-PBSA
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	29 Nov 2011 09:45
Last Modified:	29 Nov 2011 09:45
URI:	http://eprints.iisc.ac.in/id/eprint/42407

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