The MCM helicase displays distinct roles controlling dNTP synthesis and preventing genetic instability through physical interactions with the RNR complex

The helicase MCM and the ribonucleotide reductase RNR are the complexes that provide the substrates (ssDNA templates and dNTPs, respectively) for DNA replication. Here, we demonstrate that MCM interacts physically with RNR and some of its regulators, including the kinases Rad53 and Dun1. Partial disruption of the MCM/RNR interactions increases the levels of dNTPs under unperturbed conditions, pointing to a role for MCM counteracting excessive RNR activity. In response to DNA damage, most of these physical interactions augment and this increase depends on Dun1. Partial disruption of the MCM/RNR interactions does not affect the pool of dNTPs under these conditions. However, this disruption impairs the release of Rad52 from the DNA repair centers despite the lesions are repaired, leading to hypermutagenesis and sensitivity to genotoxic agents. Therefore, the MCM/RNR interactions play non-canonical roles preventing by distinct mechanisms excessive dNTP synthesis and persistent Rad52 centers.