title: Role of Swi6/HP1 self-association-mediated recruitment of Clr4/Suv39 in establishment and maintenance of heterochromatin in fission yeast.
abstract: Swi6/HP1, an evolutionarily conserved protein, is critical for heterochromatin assembly in fission yeast and higher eukaryotes. In fission yeast, histone deacetylation by histone deacetylases is thought to be followed by H3-Lys-9 methylation by the histone methyltransferase Clr4/Suv39H1. H3-Lys-9-Me2 interacts with the chromodomain of Swi6/HP1. Swi6/HP1 is thought to act downstream of Clr4/Suv39, and further self-association of Swi6/HP1 is assumed to stabilize the heterochromatin structure. Here, we show that the self-association-defective mutant of Swi6 does not interact with Clr4. It not only fails to localize to heterochromatin loci but also interferes with heterochromatic localization of H3-Lys-9-Me2 (and thereby Clr4) and the endogenous Swi6 in a dominant negative manner. Thus, self-association of Swi6/HP1 helps in binding to and recruitment of Clr4 and thereby in establishment and maintenance of heterochromatin by a concerted rather than a sequential mechanism.
authors.affiliation: Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India.
authors.forename: Swati
authors.initials: S
authors.lastname: Haldar
authors.forename: Ashok
authors.initials: A
authors.lastname: Saini
authors.forename: Jagpreet Singh
authors.initials: JS
authors.lastname: Nanda
authors.forename: Sharanjot
authors.initials: S
authors.lastname: Saini
authors.forename: Jagmohan
authors.initials: J
authors.lastname: Singh
mesh_terms: D000107:Acetylation; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D006570:Heterochromatin / Q000235:genetics / Q000378:metabolism*; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000235:genetics / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D006570:Heterochromatin; D006657:Histones; D029702:Schizosaccharomyces pombe Proteins; C465958:Swi6 protein, S pombe; D000076983:Histone Methyltransferases; D008780:Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; C112744:clr4 protein, S pombe