Novel non-canonical deadenylation by the CCR4-NOT complex     — University of Technology
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Novel non-canonical deadenylation by the CCR4-NOT complex     (14235)

Sho Niinuma 1 2 , Takashi Fukaya 1 2 , Yukihide Tomari 1 2
  1. Department of Medical Genome Sciences, The university of Tokyo, Bunkyo-ku, Tokyo, Japan
  2. Institute of Molecular and Cellular Biosciences, The university of Tokyo, Bunkyo-ku, Tokyo, Japan

 Shortening of the poly(A) tail is an important process in the regulation of mRNA turnover and protein synthesis in eukaryotes. The CCR4-NOT complex, which contains two different deadenylases CCR4 and CAF1, plays a major role in deadenylation. It has been believed that both CCR4 and CAF1 are A-specific 3´ to 5´ exoribonucleases in Drosophila melanogaster. Here, we biochemically characterized these two deadenylases using S2 cell lysate and recombinant CAF1/CCR4 heterodimer. We found that both CAF1 and CCR4 can remove a poly(A) sequence internalized by a short unrelated sequence. This non-canonical activity was dependent on the balance between the length of the internalized poly(A) sequence and that of the downstream non-A sequence. Of note, both CAF1 and CCR4 removed the non-A sequence in an exonucleolytic manner. These results suggest that CAF1 and CCR4 have an intrinsic activity to remove the 3´-terminal ribonucleotide regardless of its identity, when they recognize an upstream poly(A) sequence of sufficient length.

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