title: The roles of 3'-exoribonucleases and the exosome in trypanosome mRNA degradation.
abstract: The degradation of eukaryotic mRNAs can be initiated by deadenylation, decapping, or endonuclease cleavage. This is followed by 5'-3' degradation by homologs of Xrn1, and/or 3'-5' degradation by the exosome. We previously reported that, in African trypanosome Trypanosoma brucei, most mRNAs are deadenylated prior to degradation, and that depletion of the major 5'-3' exoribonuclease XRNA preferentially stabilizes unstable mRNAs. We now show that depletion of either CAF1 or CNOT10, two components of the principal deadenylation complex, strongly inhibits degradation of most mRNAs. RNAi targeting another deadenylase, PAN2, or RRP45, a core component of the exosome, preferentially stabilized mRNAs with intermediate half-lives. RRP45 depletion resulted in a 5' bias of mRNA sequences, suggesting action by a distributive 3'-5' exoribonuclease. Results suggested that the exosome is involved in the processing of trypanosome snoRNAs. There was no correlation between effects on half-lives and on mRNA abundance.
authors.affiliation: Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, D69120 Heidelberg, Germany.
authors.forename: Abeer
authors.initials: A
authors.lastname: Fadda
authors.forename: Valentin
authors.initials: V
authors.lastname: Färber
authors.forename: Dorothea
authors.initials: D
authors.lastname: Droll
authors.forename: Christine
authors.initials: C
authors.lastname: Clayton
mesh_terms: D002460:Cell Line; D019295:Computational Biology; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism*; D063326:Exosome Multienzyme Ribonuclease Complex / Q000235:genetics / Q000378:metabolism*; D006207:Half-Life; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D020871:RNA Stability; D034443:RNA Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism*; D020537:RNA, Small Nucleolar / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology / Q000235:genetics*
chemical_list: D046912:Multiprotein Complexes; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D020537:RNA, Small Nucleolar; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex
keywords: CAF1; PAN2; Trypanosoma; deadenylation; exosome; mRNA decay; mRNA degradation