Visualization of Human Dmc1 Presynaptic Filaments

Meiosis is initiated by the programmed formation of DNA double-strand breaks (DSBs). These DSBs are repaired by homologous recombination to promote crossover formation that ensures proper chromosomal segregation in meiosis. hRad51 and hDmc1 are two human recombinases present during meiosis that are homologous to the RecA recombinase from Escherichia coli . The hRad51 and hDmc1 recombinases bind the nucleolytically processed ends of the DSB forming a presynaptic filament. Formation of the presynaptic filament is necessary for the search for homology and the progression of recombination. In this chapter, we provide a method to purify hDmc1 and prepare samples for visualizing hDmc1 nucleoprotein presynaptic filaments via transmission electron microscopy.