title: RNase III cleaves eukaryotic preribosomal RNA at a U3 snoRNP-dependent site.
abstract: A yeast gene homologous to bacterial RNase III (RNT1) encodes a double-strand-specific endoribonuclease essential for ribosome synthesis. Two rRNA processing events are blocked in cells temperature sensitive for RNT1: cleavage at the snoRNA-dependent AO site in the 5' ETS and cleavage in the 3' ETS. Recombinant RNT1 protein accurately cleaves a synthetic 5' ETS RNA at AO site in vitro, in the absence of snoRNA or other factors. A synthetic 3' ETS substrate is specifically cleaved at a site 21 nt downstream of the 3' end 28S rRNA. These observations show that a protein endonuclease collaborates with snoRNAs in eukaryotic rRNA processing and exclude a catalytic role for snoRNAs at certain pre-rRNA cleavage.
authors.affiliation: Biology Department, University of California, Santa Cruz 95064 ,USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Elela
authors.forename: H
authors.initials: H
authors.lastname: Igel
authors.forename: M
authors.initials: M
authors.lastname: Ares
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000235:genetics; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012337:RNA, Ribosomal, 18S / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism*; D043244:Ribonuclease III; D013379:Substrate Specificity; D015003:Yeasts / Q000201:enzymology / Q000235:genetics*
chemical_list: D009711:Nucleotides; D012322:RNA Precursors; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S; D012342:RNA, Small Nuclear; D004247:DNA; D004722:Endoribonucleases; D043244:Ribonuclease III