Modulation of DNA Repair by the Protein Component of Chromatin

Brown University, Providence RI

Investigators

Abstract

The DNA in cells is constantly exposed to reactive molecules that can chemically alter bits of the DNA. Because DNA serves as the source of genetic information for cellular life, cells have devised sophisticated methods for repairing damaged DNA. Effective repair is necessary for cellular survival and transfer of error-free genetic material to the next generation. Despite the importance of DNA repair, there is still much we do not understand about the process. A focus in this project is to study how DNA repair is influenced by the type of DNA packaging that occurs in the nucleus, whereby strands of DNA are wound around cylindrical protein cores, like thread around a spool. By assembling damage-containing DNA wrapped around protein cores in the laboratory, researchers will apply cutting-edge methods to study how DNA packaging affects the ability of cells to replace damaged segments in DNA with new ones. The research will be carried out by graduate and undergraduate research as part of their professional training for careers in STEM. Collaborations with two female faculty and their students at colleges for women will expand the broader research opportunities. Oxidation, alkylation, and deamination of DNA bases can cause mutations and halt replication; therefore, to maintain genomic stability, this kind of damage must be repaired. Base excision repair (BER) is a coordinated series of enzyme-catalyzed chemical reactions in which the damaged base is removed and replaced. Despite our significant knowledge of BER, much of what has been learned is based on repair of damage in DNA templates devoid of the chromatin proteins that package DNA in the nucleus. This project focuses on the ability of the protein component of chromatin, the histones, to modulate initiation of BER. Using biochemical methodologies and kinetics techniques, the research will provide a comprehensive description of the ability of histones to govern DNA repair in the compacted environment of chromatin. The specific goals of the research are (i) to determine the ability of variants of the histone proteins to regulate BER, (ii) to understand how post-translational modification of histones influences BER, and (iii) to establish the contribution of the terminal regions of the histones to their overall activity. The results are expected to provide a deeper understanding of how BER occurs in the nuclear context. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.