Crucial Residues Modulating Interface of hBcl-B - hBaxBH3 Heterodimer as Probed by Computational Methods

Abstract

Cancerous cells develop resistance to cell death by over expression of anti-apoptotic proteins, which are specific to interact with pro-apoptotic and BH3-only proteins of Bcl-2 family. Delineating crucial residues mediating the heterodimer complexes (anti-apoptotic proteins -pro-apoptotic/BH3-only proteins) is indispensable to develop specific antagonists to anti-apoptotic proteins. In these backgrounds, we have herein reported crucial residues of hBaxBH3 and hBcl-B (an anti-apoptotic protein specifically interacts with human Bax but does not interact with human Bak) for hetero dimerization of the polypeptides and as well validated the structural determinants of the polypeptides through variety of virtual 'alanine mutants' and 'switch mutants' by using an array of computational methods. Residues such as D53, S60, E61, K64, E69 and D71 of hBaxBH3 and R45, H50, F53, F54, Y57, M71, S74, V75, R86, V88, T89, found to be crucial residues of the polypeptides for intermolecular interaction leading hetero dimerization. Moreover, 'pharmacophoric residues' for the hBaxBH3 and hBcl-B have also been figured out and rationalized.