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IMAGE: CtIP/Ctp1 stimulates endonuclease activity of the MRN complex, which not only polishes dirty ends of DNA breaks, but promotes accurate repair of DNA breaks through the homologous recombination mechanism. view more
Credit: PNAS
Scientists at Tokyo Institute of Technology (Tokyo Tech) have uncovered mechanisms underlying the activation of the MRN complex the cell s DNA scissors. Using purified yeast proteins, they demonstrated that phosphorylation of Ctp1, a homolog of a tumor-suppressor protein, plays a key role in activating MRN complex s DNA clipping activity. Intriguingly, a short segment of yeast Ctp1 or its human counterpart could stimulate endonuclease activity of their respective MRN complexes, suggesting its conserved function across species.