Biomolecular condensates amplify mRNA decapping by biasing enzyme conformation

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Cells compartmentalize biochemical processes within membrane-less organelles called biological condensates.
• P-bodies are cytoplasmic condensates crucial for mRNA degradation, involved in both storage and decay.
• The mechanism balancing mRNA storage and degradation within P-bodies remains unclear.

Purpose of the Study:

• To investigate how the Dcp1/Dcp2 decapping complex's activity is regulated within P-bodies.
• To elucidate the role of phase separation and protein interactions in modulating decapping.
• To understand how enzymatic activity is controlled across different length scales in condensates.

Main Methods:

• Studied the phase separation behavior of the Dcp1/Dcp2 complex.
• Investigated the conformational changes in Dcp2 influenced by phase separation and the activator Edc3.
• Analyzed protein-protein interactions within the condensates.

Main Results:

• Dcp1/Dcp2 phase separation stabilizes an inactive conformation of Dcp2, inhibiting mRNA decapping.
• The activator Edc3 induces a conformational change in Dcp2 and alters protein interactions, stimulating decapping.
• Disrupting the inactive conformation leads to dysregulated decapping activity within P-bodies.

Conclusions:

• Enzymatic activity within condensates is regulated by a mechanism coupling molecular (ångstroms) and cellular (microns) scales.
• This regulation is achieved through modulation of protein conformation and interactions during phase separation.
• The findings suggest a model for controlling P-body function and related phase-separated compartments.