RNA polymerase I transcription and pre-rRNA processing are linked by specific SSU processome components.
Sequential events in macromolecular biosynthesis are often elegantly coordinated. The small ribosomal subunit (SSU) processome is a large ribonucleoprotein (RNP) required for processing of precursors to the small subunit RNA, the 18S, of the ribosome. We have found that a subcomplex of SSU processome proteins, the t-Utps, is also required for optimal rRNA transcription in vivo in the yeast Saccharomyces cerevisiae. The t-Utps are ribosomal chromatin (r-chromatin)-associated, and they exist in a complex in the absence of the U3 snoRNA. Transcription is required neither for the formation of the subcomplex nor for its r-chromatin association. The t-Utps are associated with the pre-18S rRNAs independent of the presence of the U3 snoRNA. This association may thus represent an early step in the formation of the SSU processome. Our results indicate that rRNA transcription and pre-rRNA processing are coordinated via specific components of the SSU processome.
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520-8024, USA.
Jennifer E G
JE
Gallagher
David A
DA
Dunbar
Sander
S
Granneman
Brianna M
BM
Mitchell
Yvonne
Y
Osheim
Ann L
AL
Beyer
Susan J
SJ
Baserga
D015153:Blotting, Western; D002843:Chromatin / Q000737:chemistry; D017931:DNA Primers; D047468:Immunoprecipitation; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D012318:RNA Polymerase I / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012337:RNA, Ribosomal, 18S / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic / Q000502:physiology*
D002843:Chromatin; D017931:DNA Primers; D012322:RNA Precursors; D012337:RNA, Ribosomal, 18S; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D012318:RNA Polymerase I