How distribution of Sir2 between telomere and rDNA is regulated is not known. Within the nucleus, Sir2 is associated with telomere clusters in the nuclear periphery and rDNA in the nucleolus and regulates gene silencing at these genomic sites.
more Silent information regulator 2 (Sir2), the founding member of the conserved sirtuin family of NAD(+)-dependent histone deacetylase, regulates several physiological processes including genome stability, gene silencing, metabolism and life span in yeast. Silent information regulator 2 (Sir2), the founding member of the conserved sirtuin family of NAD. SUMO modification of Sir2 impairs interaction with Sir4 but not Net1 and, furthermore, SUMO modified Sir2 shows predominant nucleolar localization. Mutating K215 alone counteracts the inhibitory effect of Siz2 on telomeric silencing. We identify Siz2 as the key SUMO ligase and show that multiple lysines in Sir2 are subject to this sumoylation activity. Here we show that Sir2 is sumoylated and this modification modulates the intra-nuclear distribution of Sir2. These findings suggest that dRif1 is an adaptor for PP1 and functions by recruiting PP1 to multiple sites on the chromosome. Ectopic expression of dRif1 causes enlarged larval imaginal discs and early pupal lethality which is completely reversed by co-expression of PP1 87B, the major protein phosphatase in Drosophila, indicating genetic and functional interaction. dRif1 associates with chromosomes in a mitotic stage-dependent manner coinciding with dephosphorylation of histones. In multiple tissues dRif1 colocalizes with HP1, a protein known to orchestrate timing of replication in fly. In the present study, we show that Drosophila Rif1 is essential for normal fly development and loss of dRif1 impairs temporal regulation of initiation of DNA replication. Previously we had identified that all Rif1 homologues have PP1 interacting SILK-RVxF motif. more Rif1, identified as a regulator of telomerase in yeast, is an evolutionarily conserved protein and functions in diverse processes including telomere length regulation, epigenetic gene regulation, anti-checkpoint activity, DNA repair and establishing timing of firing at replication origins. Rif1, identified as a regulator of telomerase in yeast, is an evolutionarily conserved protein an. Our study thus demonstrates a key role for protein. Importantly, loss of the deSUMOylating enzyme CgUlp2 leads to highly reduced SUMO protein levels, and impaired growth, sensitivity to multiple stress conditions, reduced adherence to epithelial cells and poor colonization of specific tissues in mice. We demonstrate that SUMOylation is an essential process and that adaptation to stress involves changes in global SUMOylation in C. We identified the enzymes involved in SUMO conjugation and show that there is strong conservation between S. As these are key factors in determination of fungal virulence, in this study, we have investigated the importance of SUMOylation in the human pathogen, Candida glabrata. SUMOylation is essential for cell growth, division and adaptation to stress in most organisms including fungi. more Regulation of protein function by reversible posttranslational modification, SUMOylation, is widely conserved in the eukaryotic kingdom. Regulation of protein function by reversible posttranslational modification, SUMOylation, is wide.
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