RT Journal Article
SR Electronic
T1 An RNA Degradation Complex Required for Spreading and Epigenetic Inheritance of Heterochromatin
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 870766
DO 10.1101/870766
A1 Gergana Shipkovenska
A1 Alexander Durango
A1 Marian Kalocsay
A1 Steven P. Gygi
A1 Danesh Moazed
YR 2019
UL http://biorxiv.org/content/early/2019/12/11/870766.abstract
AB Heterochromatin assembly requires the methylation of histone H3 lysine 9 by the Clr4(Suv39h) methyltransferase and both the spreading and epigenetic inheritance of heterochromatin involve the recognition of H3K9me-containing nucleosomes by Clr4 and catalysis of H3K9me on adjacent nucleosomes. How this read-write mechanism overcomes obstacles posed by RNA polymerase II and nascent RNA in its path is not fully understood. Here we identify a role for the highly conserved and essential Rix1-containing complex (here referred to as the rixosome), with known RNA endonuclease and polynucleotide kinase activities required for ribosomal RNA (rRNA) processing, in spreading and epigenetic inheritance of heterochromatin. Viable mutations in rixosome subunits that disrupt its association with Swi6/HP1 fail to localize to heterochromatin, lead to accumulation of heterochromatic RNAs, and block spreading of H3K9me and silencing away from nucleation sites into actively transcribed regions. These findings reveal a new pathway for degradation of heterochromatic RNAs with essential roles in heterochromatin spreading and inheritance.