The role of deadenylation in the degradation of unstable mRNAs in trypanosomes

• Autores: Schwede, A.; Manful, T.; Jha, B.A.; Helbig, C.; Bercovich, N.; Stewart, M.; Clayton, C.
• Año de publicación: 2009
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Nucleic Acids Res. 2009;37(16):5511-5528
• Materia: chromatin assembly factor 1; gene product; messenger RNA; protein EP; ribosome protein; unclassified drug; EP procyclin protein, Trypanosoma brucei; membrane protein; mRNA deadenylase; phosphoglycerate kinase; protozoal protein; ribonuclease; 3' untranslated region; 5' untranslated region; adenylation; article; controlled study; cytoplasm; gene amplification; gene sequence; nonhuman; priority journal; protein depletion; protein targeting; RNA degradation; RNA interference; Trypanosoma; animal; chemistry; drug antagonism; enzymology; genetics; genome; growth, development and aging; metabolism; physiology; RNA stability; Eukaryota; Metazoa; Animals; Cytoplasm; Genome, Protozoan; Membrane Glycoproteins; Phosphoglycerate Kinase; Protozoan Proteins; Ribonucleases; RNA Interference; RNA Stability; RNA, Messenger; Trypanosoma
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

Removal of the poly(A) tail is the first step in the degradation of many eukaryotic mRNAs. In metazoans and yeast, the Ccr4/Caf1/Not complex has the predominant deadenylase activity, while the Pan2/Pan3 complex may trim poly(A) tails to the correct size, or initiate deadenylation. In trypanosomes, turnover of several constitutively-expressed or long-lived mRNAs is not affected by depletion of the 5'-3' exoribonuclease XRNA, but is almost completely inhibited by depletion of the deadenylase CAF1. In contrast, two highly unstable mRNAs, encoding EP procyclin and a phosphoglycerate kinase, PGKB, accumulate when XRNA levels are reduced. We here show that degradation of EP mRNA was partially inhibited after CAF1 depletion. RNAi-targeting trypanosome PAN2 had a mild effect on global deadenylation, and on degradation of a few mRNAs including EP. By amplifying and sequencing degradation intermediates, we demonstrated that a reduction in XRNA had no effect on degradation of a stable mRNA encoding a ribosomal protein, but caused accumulation of EP mRNA fragments that had lost substantial portions of the 5' and 3' ends. The results support a model in which trypanosome mRNAs can be degraded by at least two different, partially independent, cytoplasmic degradation pathways attacking both ends of the mRNA. © 2009 The Author(s).
Fil:Bercovich, N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.