Control of mRNA decapping by autoinhibition

Area of Science:

• Molecular Biology
• Biochemistry
• RNA Biology

Background:

• 5' mediated cytoplasmic RNA decay is a crucial eukaryotic process.
• The role of intrinsically disordered regions (IDRs) in RNA decay pathways remains largely unexplored.
• The Dcp1:Dcp2 complex is central to decapping, but its regulation by IDRs is not well understood.

Purpose of the Study:

• To investigate the function of intrinsically disordered regions (IDRs) in the Dcp1:Dcp2 complex.
• To elucidate the mechanism by which cofactors Edc1 and Edc3 regulate decapping activity.
• To understand the combinatorial control of 5' mRNA decay.

Main Methods:

• Reconstitution of the Dcp1:Dcp2 complex with its disordered C-terminus.
• Biochemical assays to measure decapping activity.
• Analysis of cofactor interactions with IDRs and enzyme activity.

Main Results:

• The C-terminal IDRs of Dcp1:Dcp2 mediate autoinhibition via linear interaction motifs.
• Edc3 alleviates autoinhibition by binding IDRs and destabilizing an inactive enzyme conformation.
• Edc1 stabilizes the catalytic transition state, and both Edc1 and Edc3 are required for full activation.

Conclusions:

• Combinatorial control by protein cofactors regulates decapping enzyme activity.
• Edc3 and Edc1 employ distinct mechanisms to activate the autoinhibited Dcp1:Dcp2 complex.
• This regulatory principle is likely conserved across various 5' mRNA decay pathways.