ABSTRACT
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, F93 and F159 of hBcl-B were 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.
ABSTRACT
Mycobacterium tuberculosis (Mtb) causing tuberculosis as an intracellular pathogen initially infects alveolar macrophages following aerosol inhalation. Thus, macrophages play a critical role in the establishment of Mtb infection and macrophage cell death, a common outcome during Mtb infection, may initiate host- or pathogen-favored immune responses, resulting in facilitating protection or pathogenesis, respectively. In addition, virulent Mtb strains are known to inhibit apoptosis and consequently down-regulates immune response using a variety of strategies. In many recent studies have shown that virulent Mtb can either augment or reduce apoptosis by regulating expression of pro-apoptotic and anti-apoptotic proteins belonging to Bcl-2 family proteins. In this review, we will discuss and dissect the apoptotic pathways of Bcl-2 family proteins in Mtb-infected macrophages.