The Role of DMC1 in Meiotic Homologous Recombination in \u3ci\u3eArabidopsis Thaliana\u3c/i\u3e

Dmc1 is a meiosis-specific recombinase that is integral to DNA double-strand break (DSB) repair using the homologous recombination pathway. This pathway uses a homologous sister chromatid as a template for DNA repair synthesis. After a DSB is formed, DNA end resection occurs, leaving a 3’single strand DNA (ssDNA) overhang. Dmc1 polymerizes on this ssDNA to form a right-handed helical protein filament that catalyzes the search for a homologous DNA region to facilitate strand invasion. Other protein factors such as Hop2-Mnd1 are recruited to promote Dmc1 mediated recombination. Recently, a mutation in Dmc1 was found to cause sterility in Arabidopsis thaliana. To determine the impact this mutation has on the recombination activities of Dmc1, I expressed and purified wildtype and mutant atDmc1 proteins from bacteria. The purified wildtype and variant Dmc1 proteins were subjected to various biochemical analyses that monitored the ability of Dmc1 to catalyze the search for homology and perform DNA strand exchange. The variant Dmc1 protein was severely attenuated in its ability to perform homology directed repair. Protein factors such as Hop2-Mnd1 and CAF1G in Arabidopsis thaliana potentially modulate the activity of Dmc1 and may be able to compensate for this loss of activity. The results from this project provide insight into the function of a highly conserved amino acid residue within Dmc1 and may explain why a mutation of this amino acid results in sterility in plants