RESUMO
Familial inheritance of breast and ovarian cancer is attributed to mutations discovered in functional domains of BRCA1 gene. BRCA1 is a multifunctional protein responsible for maintaining the genomic integrity and has transcriptional regulatory function encoded in its C-terminal region. The different amino-terminal e extensions to BRCA1 BRCT domain are responsible for transcription activation. However, only BRCA1 BRCT (1649-1859) amino acids have been explored for its structural characteristics. Noting the importance of extended region to the N-terminus of BRCT different regions of BRCA1 which demonstrates maximum transactivation activity has been explored for their structure and functional activity. Secondary and tertiary structural analysis revealed a limited alpha-helical content with well-folded tertiary structure. In silico tools were used to corroborate the in vitro results. Amino acids composition and sequence analysis display a propensity for intrinsic disorder and coiled-coil formation in BRCA1 (1396-1863) (BRCA1-TAD). The results presented in this paper suggest the extreme flexibility in coiled-coil motif might be an important requirement in the establishment of protein-protein interaction networks for BRCA1.
Assuntos
Proteína BRCA1/química , Modelos Moleculares , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Sequência de Aminoácidos , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Humanos , Multimerização Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes , Relação Estrutura-Atividade , Ativação TranscricionalRESUMO
Zinc finger transcription regulatory proteins play crucial roles in cell-cycle regulation, DNA damage response and tumor genesis. Human ZBRK1 is a zinc-finger transcription repressor protein, which recognizes double helical DNA containing consensus sequences of 5'GGGXXXCAGXXXTTT3'. In the present study, we have purified recombinant DNA binding domain of ZBRK1, and studied binding with zinc ions and DNA, using biophysical techniques. The elution profile of the purified protein suggests that this ZBRK1 forms a homotetramer in solution. Dissociation and pull down assays also suggest that this domain forms a higher order oligomer. The ZBRK1-DNA binding domain acquires higher stability in the presence of zinc ions and DNA. The secondary structure of the ZBRK1-DNA complex is found to be significantly altered from the standard B-DNA conformation.