Locating the Protein Binding Region of p53 and the Intrinsically Disordered Region of BRCA1

Abstract

BRCA1 and p53 have been shown to interact in tumor supressor pathways that protect against hereditary breast and ovarian cancer. Finding the physical binding location associated with this interplay is important in assessing cancer risk and determining molecular details of the interaction. This project aimed to identify the protein binding region of p53 with the intrinsically disordered region of BRCA1. We cloned select regions of human p53 and BRCA1 proteins into E. coli bacteria, then harvested and purified the proteins. A pull-down assay was performed to test binding affinity between a segment of p53 and two different length BRCA1 constructs. The assay showed that neither the construct containing the BRCA1 amino acids between 772-1126 nor the construct with amino acids between 896-2290 interacted with p53. This indicated that these amino acids alone are not sifficient for binding of p53 and BRCA1. Our results could indicate that a third-party binding mediator is necessary in vivo. This information expands upon our knowledge of the p53 and BRCA1 binding interaction and can be used in a clinical setting to evaluate risk associated with mutations in experimental regions.