Exploring The Effects Of Phosphorylation On Brca1's Intrinsically Disordered Region On Structure And Function

Morote-Costas, Brian

Publication

Exploring The Effects Of Phosphorylation On Brca1's Intrinsically Disordered Region On Structure And Function

Morote-Costas, Brian

Date

2019

Additional date(s)

2019-12-18

Abstract

The proper function of the breast cancer susceptibility gene 1 (BRCA1) and its subsequent protein in the human body is vital to healthy individuals. Upon phosphorylation, the intrinsically disordered central region of BRCA1 interacts with another tumor suppressor protein called PALB2 (Partner and Localizer of BRCA2) to form a complex which conducts DNA repair. The molecular details of how phosphorylation affects BRCA1's structure and function regarding PALB2 binding are not well understood. Given that PALB2 binds to BRCA1 using a helical interface, PALB2 is known to form coiled-coils upon complexing with other proteins, and phosphorylation occurs upon the sensing of DNA damage prior to the complex formation, we hypothesized that BRCA1 phosphorylation could serve as a mechanism to induce a helical structure of its intrinsically disordered region, promote complex formation, and enable DNA damage repair pathways. To test this hypothesis we created three mutations in the central region that mimic activation of BRCA1 to identify possible significant changes at the molecular level of BRCA1 and its protein-protein interaction. Through circular dichroism and nuclear magnetic resonance experiments, we found that phosphorylation does not induce changes in BRCA1's secondary structure. Using isothermal titration calorimetry analysis we obtained data that suggests phosphorylation is a mechanism by which BRCA1-PALB2 complex formation is regulated as it triggers a change in binding behavior between the two proteins.