Nse1, Nse2, and a novel subunit of the Smc5-Smc6 complex, Nse3, play a crucial role in meiosis.

Pebernard S, McDonald WH, Pavlova Y, Yates JR, Boddy MN
Mol Biol Cell. 2004 15 (11): 4866-76

PMID: 15331764 · PMCID: PMC524734 · DOI:10.1091/mbc.e04-05-0436

The structural maintenance of chromosomes (SMC) family of proteins play key roles in the organization, packaging, and repair of chromosomes. Cohesin (Smc1+3) holds replicated sister chromatids together until mitosis, condensin (Smc2+4) acts in chromosome condensation, and Smc5+6 performs currently enigmatic roles in DNA repair and chromatin structure. The SMC heterodimers must associate with non-SMC subunits to perform their functions. Using both biochemical and genetic methods, we have isolated a novel subunit of the Smc5+6 complex, Nse3. Nse3 is an essential nuclear protein that is required for normal mitotic chromosome segregation and cellular resistance to a number of genotoxic agents. Epistasis with Rhp51 (Rad51) suggests that like Smc5+6, Nse3 functions in the homologous recombination based repair of DNA damage. We previously identified two non-SMC subunits of Smc5+6 called Nse1 and Nse2. Analysis of nse1-1, nse2-1, and nse3-1 mutants demonstrates that they are crucial for meiosis. The Nse1 mutant displays meiotic DNA segregation and homologous recombination defects. Spore viability is reduced by nse2-1 and nse3-1, without affecting interhomolog recombination. Finally, genetic interactions shared by the nse mutants suggest that the Smc5+6 complex is important for replication fork stability.

MeSH Terms (26)

Amino Acid Sequence Cell Cycle Proteins Cell Nucleus Cell Survival Chromosomal Proteins, Non-Histone Chromosomes DNA Repair Gamma Rays Gene Deletion Immunoblotting Immunoprecipitation Meiosis Mitosis Models, Biological Molecular Sequence Data Mutation Nuclear Proteins Peptides Protein Binding Recombination, Genetic Saccharomyces cerevisiae Proteins Schizosaccharomyces Schizosaccharomyces pombe Proteins Sequence Homology, Amino Acid Two-Hybrid System Techniques Ultraviolet Rays

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