title: The FACT complex interacts with the E3 ubiquitin ligase Psh1 to prevent ectopic localization of CENP-A.
abstract: Centromere identity and its epigenetic maintenance require the incorporation of a histone H3 variant called CENP-A at centromeres. CENP-A mislocalization to ectopic sites may disrupt chromatin-based processes and chromosome segregation, so it is important to uncover the mechanisms by which this variant is exclusively localized to centromeres. Here, we identify a role for the conserved chromatin-modifying complex FACT (facilitates chromatin transcription/transactions) in preventing budding yeast CENP-A(Cse4) mislocalization to euchromatin by mediating its proteolysis. The Spt16 subunit of the FACT complex binds to Psh1 (Pob3/Spt16/histone), an E3 ubiquitin ligase that targets CENP-A(Cse4) for degradation. The interaction between Psh1 and Spt16 is critical for both CENP-A(Cse4) ubiquitylation and its exclusion from euchromatin. We found that Psh1 cannot efficiently ubiquitylate CENP-A(Cse4) nucleosomes in vitro, suggesting that additional factors must facilitate CENP-A(Cse4) removal from chromatin in vivo. Consistent with this, a Psh1 mutant that cannot associate with FACT has a reduced interaction with CENP-A(Cse4) in vivo. Together, our data identify a previously unknown mechanism to maintain centromere identity and genomic stability through the FACT-mediated degradation of ectopically localized CENP-A(Cse4).
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
authors.forename: Gary M R
authors.initials: GM
authors.lastname: Deyter
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA sbiggins@fhcrc.org.
authors.forename: Sue
authors.initials: S
authors.lastname: Biggins
mesh_terms: D001324:Autoantigens / Q000378:metabolism*; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D022041:Euchromatin / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000378:metabolism*; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055550:Protein Stability; D021381:Protein Transport; D059748:Proteolysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D035602:Transcriptional Elongation Factors / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D001324:Autoantigens; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D022041:Euchromatin; C541535:FACT protein, S cerevisiae; D006609:High Mobility Group Proteins; D009707:Nucleosomes; D010445:Peptide Elongation Factors; C071238:SPT16 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035602:Transcriptional Elongation Factors; C554184:Psh1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases
keywords: CENP-A; FACT; Psh1; centromere; proteolysis; ubiquitylation