Silencing in yeast rDNA chromatin: reciprocal relationship in gene expression between RNA polymerase I and II.
About half of approximately 150 rRNA genes are transcriptionally active in Saccharomyces cerevisiae. Chromatin structures in the inactive, and not the active, copies were previously thought to silence both rRNA genes and reporter Pol II genes. Contrary to this belief, we found that silencing of reporters is much stronger in a mutant with approximately 25 rDNA copies, all of which are transcriptionally active. By integrating reporter gene mURA3 with an inactive rDNA copy missing the Pol I promoter, we found that mURA3 is not silenced in chromosomal rDNA repeats. Together with the demonstration of a requirement for active Pol I in silencing, these results show a reciprocal relationship in gene expression between Pol I and Pol II in rDNA.
Cioci
Francesco
F
Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA.
Vu
Loan
L
Eliason
Kristilyn
K
Oakes
Melanie
M
Siddiqi
Imran N
IN
Nomura
Masayasu
M
D001483:Base Sequence / Q000235:genetics; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D020868:Gene Silencing / Q000502:physiology*; D017930:Genes, Reporter / Q000235:genetics; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012318:RNA Polymerase I / Q000235:genetics*; D012319:RNA Polymerase II / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics
D002843:Chromatin; D004275:DNA, Ribosomal; D005656:Fungal Proteins; D012319:RNA Polymerase II; D012318:RNA Polymerase I