The structure of NoRC-associated RNA is crucial for targeting the chromatin remodelling complex NoRC to the nucleolus.
Silencing of ribosomal RNA genes (rDNA) requires binding of the chromatin remodelling complex NoRC to RNA that is complementary to the rDNA promoter. NoRC-associated RNA (pRNA) folds into a conserved stem-loop structure that is required for nucleolar localization and rDNA silencing. Mutations that disrupt the stem-loop structure impair binding of TIP5, the large subunit of NoRC, to pRNA and abolish targeting of NoRC to nucleoli. Binding to pRNA results in a conformational change of TIP5, as shown by enhanced sensitivity of TIP5 towards trypsin digestion. Our results indicate an RNA-dependent mechanism that targets NoRC to chromatin and facilitates the interaction with co-repressors that promote heterochromatin formation and rDNA silencing.
Mayer
Christine
C
Division of Molecular Biology of the Cell II, German Cancer Research Center, DKFZ-ZMBH-Alliance, INF 581, D-69120 Heidelberg, Germany. christine.mayer@dkfz.de
Neubert
Melanie
M
Grummt
Ingrid
I
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection; D000092468:Bromodomain Containing Proteins
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D012313:RNA; D011993:Recombinant Fusion Proteins; C499051:Baz2a protein, mouse; D000092468:Bromodomain Containing Proteins