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Bujnicki Lab Homepage

Deadenylation-independent decay in Saccharomyces cerevisiae

Proteins:
5'-3' exoribonuclease
40S ribosomal protein S28-B
ATP-dependent RNA helicase DHH1
DNA topoisomerase 2-associated protein PAT1
Enhancer of mRNA-decapping protein 3
Enzymatic
complexes:
DCP1-DCP2 decapping complex


Two unrelated transcripts, RPS28B and EDC1 mRNAs, bypass the deadenylation step to be directly decapped.

The S. cerevisiae RPS28B mRNA undergoes decay through an intriguing autoregulatory mechanism shown in the picture below. The Rps28B protein binds directly to a stem-loop structure in the 3′ UTR of its own mRNA and recruits Edc3 — an enhancer of decapping. This presumably leads to association of other decapping factors and allows deadenylation-independent decapping of the transcript.

The S. cerevisiae EDC1 mRNA, which encodes the decapping-regulatory protein Edc1, also decays by a deadenylation-independent decapping pathway. In this instance, deadenylation seems to be prevented by a novel interaction between the poly(A) tail and a poly(U) stretch in the 3′ UTR. This intramolecular pairing blocks access to the deadenylase. That Edc1 encodes a decapping regulator and is decayed by a pathway that is highly sensitive to decapping indicates the possible existence of feedback regulation. Also, decapping of EDC1 mRNA requires some subunits of the CCR4–NOT complex, which signifies an interesting link between the deadenylation complex and decapping.  [PMID: 17245413]
 



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Last modification of this entry: 2012-04-18 09:43:56
Edited by a user: kaja
Edited content: Changed rna_type.

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