title: Transcription elongation by RNA polymerase I is linked to efficient rRNA processing and ribosome assembly.
abstract: The synthesis of ribosomes in eukaryotic cells is a complex process involving many nonribosomal protein factors and snoRNAs. In general, the processes of rRNA transcription and ribosome assembly are treated as temporally or spatially distinct. Here, we describe the identification of a point mutation in the second largest subunit of RNA polymerase I near the active center of the enzyme that results in an elongation-defective enzyme in the yeast Saccharomyces cerevisiae. In vivo, this mutant shows significant defects in rRNA processing and ribosome assembly. Taken together, these data suggest that transcription of rRNA by RNA polymerase I is linked to rRNA processing and maturation. Thus, RNA polymerase I, elongation factors, and rRNA sequence elements appear to function together to optimize transcription elongation, coordinating cotranscriptional interactions of many factors/snoRNAs with pre-rRNA for correct rRNA processing and ribosome assembly.
authors.affiliation: Department of Biological Chemistry, University of California, Irvine, 240-D Medical Sciences I, Irvine, CA 92697-1700, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Schneider
authors.forename: Antje
authors.initials: A
authors.lastname: Michel
authors.forename: Martha L
authors.initials: ML
authors.lastname: Sikes
authors.forename: Loan
authors.initials: L
authors.lastname: Vu
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Dodd
authors.forename: Shilpa
authors.initials: S
authors.lastname: Salgia
authors.forename: Yvonne N
authors.initials: YN
authors.lastname: Osheim
authors.forename: Ann L
authors.initials: AL
authors.lastname: Beyer
authors.forename: Masayasu
authors.initials: M
authors.lastname: Nomura
mesh_terms: D005800:Genes, Fungal; D017354:Point Mutation; D021122:Protein Subunits; D012318:RNA Polymerase I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D021122:Protein Subunits; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D012318:RNA Polymerase I