title: Targeted sister chromatid cohesion by Sir2.
abstract: The protein complex known as cohesin binds pericentric regions and other sites of eukaryotic genomes to mediate cohesion of sister chromatids. In budding yeast Saccharomyces cerevisiae, cohesin also binds silent chromatin, a repressive chromatin structure that functionally resembles heterochromatin of higher eukaryotes. We developed a protein-targeting assay to investigate the mechanistic basis for cohesion of silent chromatin domains. Individual silencing factors were tethered to sites where pairing of sister chromatids could be evaluated by fluorescence microscopy. We report that the evolutionarily conserved Sir2 histone deacetylase, an essential silent chromatin component, was both necessary and sufficient for cohesion. The cohesin genes were required, but the Sir2 deacetylase activity and other silencing factors were not. Binding of cohesin to silent chromatin was achieved with a small carboxyl terminal fragment of Sir2. Taken together, these data define a unique role for Sir2 in cohesion of silent chromatin that is distinct from the enzyme's role as a histone deacetylase.
authors.affiliation: Department of Pharmacology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States of America.
authors.forename: Ching-Shyi
authors.initials: CS
authors.lastname: Wu
authors.forename: Yu-Fan
authors.initials: YF
authors.lastname: Chen
authors.forename: Marc R
authors.initials: MR
authors.lastname: Gartenberg
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics*; D002842:Chromatids / Q000235:genetics*; D002843:Chromatin / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D020090:Chromosome Segregation / Q000235:genetics*; D008856:Microscopy, Fluorescence; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D056565:Sirtuin 2 / Q000235:genetics / Q000502:physiology*; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D056565:Sirtuin 2; D000097722:Cohesins; C087778:SIR2 protein, S cerevisiae