Chromosome condensation factor Brn1p is required for chromatid separation in mitosis.
This work describes BRN1, the budding yeast homologue of Drosophila Barren and Xenopus condensin subunit XCAP-H. The Drosophila protein is required for proper chromosome segregation in mitosis, and Xenopus protein functions in mitotic chromosome condensation. Mutant brn1 cells show a defect in mitotic chromosome condensation and sister chromatid separation and ... segregation in anaphase. Chromatid cohesion before anaphase is properly maintained in the mutants. Some brn1 mutant cells apparently arrest in S-phase, pointing to a possible function for Brn1p at this stage of the cell cycle. Brn1p is a nuclear protein with a nonuniform distribution pattern, and its level is up-regulated at mitosis. Temperature-sensitive mutations of BRN1 can be suppressed by overexpression of a novel gene YCG1, which is homologous to another Xenopus condensin subunit, XCAP-G. Overexpression of SMC2, a gene necessary for chromosome condensation, and a homologue of the XCAP-E condensin, does not suppress brn1, pointing to functional specialization of components of the condensin complex.
Mesh Terms:
Cell Cycle Proteins, Chromatids, Chromosomes, DNA, Fungal, Drosophila Proteins, In Situ Hybridization, Fluorescence, Mitosis, Mutation, Nuclear Proteins, Saccharomyces cerevisiae
Cell Cycle Proteins, Chromatids, Chromosomes, DNA, Fungal, Drosophila Proteins, In Situ Hybridization, Fluorescence, Mitosis, Mutation, Nuclear Proteins, Saccharomyces cerevisiae
Mol. Biol. Cell
Date: Apr. 01, 2000
PubMed ID: 10749931
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