CUCU modification of mRNA promotes decapping and transcript degradation in Aspergillus nidulans.
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.
Morozov
Igor Y
IY
University of Liverpool, School of Biological Sciences, Crown Street, Liverpool L69 7ZB, United Kingdom.
Jones
Meriel G
MG
Razak
Ammar Abdul
AA
Rigden
Daniel J
DJ
Caddick
Mark X
MX
D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D014158:Transcription, Genetic
D005656:Fungal Proteins; D012333:RNA, Messenger