Biochemical analysis of the human DMC1‐I37N polymorphism

The DMC1 protein, a meiosis‐specific DNA recombinase, promotes homologous pairing and strand exchange. The I37N single nucleotide polymorphism of the human DMC1 protein was reported as a result of human genome sequencing projects. In this study, we purified the human DMC1‐I37N variant, as a recombinant protein. The DMC1 protein is known to require DNA for efficient ATP hydrolysis. By contrast, the DMC1‐I37N variant efficiently hydrolyzed ATP in the absence of DNA. Like the conventional DMC1 protein, the DMC1‐I37N variant promoted strand exchange, but it required a high Ca2+ concentration (4–8 mm), a condition that inactivates the strand‐exchange activity of the conventional DMC1 protein. These biochemical differences between the DMC1 and DMC1‐I37N proteins suggest that the DMC1‐I37N polymorphism may be a source of improper meiotic recombination, causing meiotic defects in humans.