The Nse5-Nse6 dimer mediates DNA repair roles of the Smc5-Smc6 complex.

Stabilization and processing of stalled replication forks is critical for cell survival and genomic integrity. We characterize a novel DNA repair heterodimer of Nse5 and Nse6, which are nonessential nuclear proteins critical for chromosome segregation in fission yeast. The Nse5/6 dimer facilitates DNA repair as part of the Smc5-Smc6 holocomplex ...
(Smc5/6), the basic architecture of which we define. Nse5-Nse6 [corrected] (Nse5 and Nse6) [corrected] mutants display a high level of spontaneous DNA damage and mitotic catastrophe in the absence of the master checkpoint regulator Rad3 (hATR). Nse5/6 mutants are required for the response to genotoxic agents that block the progression of replication forks, acting in a pathway that allows the tolerance of irreparable UV lesions. Interestingly, the UV sensitivity of Nse5/6 [corrected] is suppressed by concomitant deletion of the homologous recombination repair factor, Rhp51 (Rad51). Further, the viability of Nse5/6 mutants depends on Mus81 and Rqh1, factors that resolve or prevent the formation of Holliday junctions. Consistently, the UV sensitivity of cells lacking Nse5/6 can be partially suppressed by overexpressing the bacterial resolvase RusA. We propose a role for Nse5/6 mutants in suppressing recombination that results in Holliday junction formation or in Holliday junction resolution.
Mesh Terms:
Carrier Proteins, Cell Cycle Proteins, Chromosomal Proteins, Non-Histone, DNA Helicases, DNA Repair, DNA Replication, DNA-Binding Proteins, Dimerization, Endonucleases, Escherichia coli Proteins, Genome, Fungal, Genomic Instability, Holliday Junction Resolvases, Multiprotein Complexes, Mutation, Nuclear Proteins, Recombinant Proteins, Recombination, Genetic, Schizosaccharomyces, Schizosaccharomyces pombe Proteins, Ultraviolet Rays
Mol. Cell. Biol.
Date: Mar. 01, 2006
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