title: The functional role of SUMO E3 ligase Mms21p in the maintenance of subtelomeric silencing in budding yeast.
abstract: In Saccharomyces cerevisiae, subtelomeric silencing is involved in the propagation of Silent Information Regulator (SIR) proteins toward euchromatin. Numerous mechanisms are involved in antagonizing the local spread of Sir-dependent silent chromatin into neighboring euchromatin. Here, we identified a novel role for sumoylation E3 ligase Mms21 in the maintenance of subtelomeric silencing. We found that disruption of E3 ligase activity of Mms21 results in the de-repression of subtelomeric silencing. Deletion of E3 ligase domain of Mms21 led to decreased binding of Sir2p, Sir3p and Sir4 at subtelomeric chromatins and increased H3K4 tri-methylation at telomere-distal euchromatin regions, correlating with increased gene expression in two subtelomeric reporter genes. In addition, a mms21Δsl mutant caused a severe growth defect in combination with htz1Δ deletion and showed an enhanced association of Htz1 with telomere proximal regions. Taken together, our findings suggest an important role of Mms21p; it contributes to subtelomeric silencing during the formation of a heterochromatin boundary.
authors.affiliation: The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing 210096, China. ywansystemsbiology@gmail.com
authors.forename: Yakun
authors.initials: Y
authors.lastname: Wan
authors.forename: Xiao
authors.initials: X
authors.lastname: Zuo
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhuo
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Danziger
authors.forename: Zikai
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D008745:Methylation; D011485:Protein Binding; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000378:metabolism*; D016615:Telomere / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D006657:Histones; C493530:Htz1 protein, S cerevisiae; C500948:Mms21 protein, S cerevisiae; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D044767:Ubiquitin-Protein Ligases
keywords: E3 ligase; H3K4 tri-methylation; SIR complex; Telomere silencing