title: CUCU modification of mRNA promotes decapping and transcript degradation in Aspergillus nidulans.
abstract: In eukaryotes, mRNA decay is generally initiated by the shortening of the poly(A) tail mediated by the major deadenylase complex Ccr4-Caf1-Not. The deadenylated transcript is then rapidly degraded, primarily via the decapping-dependent pathway. Here we report that in Aspergillus nidulans both the Caf1 and Ccr4 orthologues are functionally distinct deadenylases in vivo: Caf1 is required for the regulated degradation of specific transcripts, and Ccr4 is responsible for basal degradation. Intriguingly disruption of the Ccr4-Caf1-Not complex leads to deadenylation-independent decapping. Additionally, decapping is correlated with a novel transcript modification, addition of a CUCU sequence. A member of the nucleotidyltransferase superfamily, CutA, is required for this modification, and its disruption leads to a reduced rate of decapping and subsequent transcript degradation. We propose that 3' modification of adenylated mRNA, which is likely to represent a common eukaryotic process, primes the transcript for decapping and efficient degradation.
authors.affiliation: University of Liverpool, School of Biological Sciences, Crown Street, Liverpool L69 7ZB, United Kingdom.
authors.forename: Igor Y
authors.initials: IY
authors.lastname: Morozov
authors.forename: Meriel G
authors.initials: MG
authors.lastname: Jones
authors.forename: Ammar Abdul
authors.initials: AA
authors.lastname: Razak
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Rigden
authors.forename: Mark X
authors.initials: MX
authors.lastname: Caddick
mesh_terms: D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins; D012333:RNA, Messenger