Multimodal Approach to Explore the Pathogenicity of BARD1, ARG 658 CYS and ILE 738 VAL Mutants

BARD1 - BRCA1 complex plays an important role in DNA damage repair, apoptosis, chromatin remodeling and other important processes required for cell survival. BRCA1 and BARD1 heterodimer possess E3 ligase activity and is involved in genome maintenance, by functioning in surveillance for DNA damage, thereby regulating multiple pathways including tumor suppression. BRCTs domains are evolutionary conserved domains present in different proteins such as BRCA1, BARD1, XRCC and MDC1 regulating damage response and cell- cycle control through protein-protein interactions. Nonetheless, the role of BARD1BRCT in recruitment of DNA repair mechanism and structural integrity with BRCA1-complex is still implicit. To explicate the role of BARD1BRCT in the DNA repair mechanism, in<i>-silico</i>, <i>in-vitro</i> and biophysical approach were applied to characterize BARD1BRCT <i>wild -type</i> and Arg658Cys and Ile738Val mutants. However, no drastic secondary and tertiary structural changes in the mutant proteins were observed. Thermal and chemical denaturation studies revealed that mutant Arg658Cys and Ile738Val has a decrease T_m and ∆G than the <i>wild- type</i>. <i>In-silico</i> studies of BARD1BRCT (568-777) and mutant protein indicates loss in structural compactness on the Ile738Val mutant. Comparative studies of <i>wild- type</i> and mutants will thus be helpful in understanding the basic role of BARD1BRCT in DNA damage repair.