Pat1 activates late steps in mRNA decay by multiple mechanisms

Area of Science:

• Molecular Biology
• RNA Metabolism
• Biochemistry

Background:

• Pat1 protein is central to mRNA metabolism, influencing splicing, translation repression, and decay.
• 5 -3 mRNA decay requires 5 -cap removal before RNA body digestion by exonucleases.
• The Pat1/Lsm1-7 complex interacts with mRNA at the 3 end to promote decapping by Dcp1/Dcp2.

Purpose of the Study:

• To elucidate the molecular mechanism by which Pat1 activates mRNA decay.
• To understand how Pat1 coordinates the assembly and activation of the decapping messenger ribonucleoprotein (mRNP).

Main Methods:

• Reconstitution of Pat1 with 5 and 3 decay factors.
• Analysis of Pat1 interactions with the Lsm1-7 complex and Dcp2.
• Biochemical assays to assess decapping activation.

Main Results:

• Pat1 stabilizes Lsm1-7 complex binding to RNA via two conserved interaction motifs.
• Pat1 directly activates Dcp2-mediated decapping by binding its C-terminal extension, relieving autoinhibition.
• Pat1 facilitates substrate binding to Dcp2.

Conclusions:

• Pat1 acts as a scaffold, coordinating the assembly of the decapping mRNP.
• Pat1's distinct domains facilitate Lsm1-7 binding and Dcp2 activation, driving 5 -3 mRNA decay.