Fig. 3

Regional sequestration of heterochromatin structural proteins at nuclear periphery. A Perinuclear anchoring of heterochromatin structural proteins in S. cerevisiae. Budding yeast silent chromatin loci, such as telomeres, HM loci and rDNA repeats are anchored to the nuclear periphery through interaction with inner nuclear membrane proteins (INMPs) and nucleoporins. At rDNA repeats, Net1 sequesters Sir2 and Cdc14 specifically during the S-phase for RENT complex formation. rDNA repeats are anchored to the nuclear periphery through interaction between INMPs Heh1/Nur1 and the cohibin components Lrs4/Csm1. Telomeric repeats are anchored to the nuclear periphery by binding to the INMP Mps3 or nucleoporin Nup170. The yKu70/80 heterodimeric complex combines with telomerase to bind to Mps3. Sir4 interacts with Mps3. Sir4 binds to Nup170 and forms a distinct complex with SUMO E3 ligase Siz2 and nuclear periphery protein Esc1. At HM loci, HML is linked to HMR via a long-range interaction. HML and HMR loci are clustered with the telomeres of chromosome III. HMR locus is anchored to nuclear periphery through Sir4-dependent manner. B Perinuclear anchoring of heterochromatin structural proteins in S. pombe. At fission yeast silent mating-type loci, the Rix1 complex (RIXC) binds to the silent chromatin domain and the boundary and nuclear rim protein Amo1 interacts with RIXC at the silent chromatin boundary for the anchoring of silent mating-type loci at the nuclear periphery. They construct concentrated foci of Swi6 and the FACT components Spt16 and Pob3 for heterochromatin maintenance and inheritance. Centromeric regions are anchored to the nuclear periphery through Lem2/Nur1. The nucleoporin components Npp106 and Nup211 lead to the nuclear periphery anchoring and silent chromatin formation of centromeres and telomeres