An Actin Remodeling Role for Arabidopsis Processing Bodies Revealed by their Proximity Interactome

Description

Cellular condensates can comprise membrane-less ribonucleoprotein assemblies with liquid-like properties. These cellular condensates influence various biological outcomes, but their liquidity hampers their isolation and characterization. Here, we investigated the composition of the condensates known as processing bodies (PBs) in the model plant Arabidopsis thaliana through a proximity-biotinylation proteomics approach. Using in situ protein–protein interaction approaches, genetics and high-resolution dynamic imaging, we show that processing bodies comprise networks that interface with membranes. Surprisingly, the conserved component of PBs, DECAPPING PROTEIN 1 (DCP1), can localize to unique plasma membrane subdomains including cell edges and vertices. We characterized these plasma membrane interfaces and discovered a developmental module that can control cell shape. This module is regulated by DCP1, independently from its role in decapping, and the actin-nucleating SCAR–WAVE complex, whereby the DCP1–SCAR–WAVE interaction confines and enhances actin nucleation. This study reveals an unexpected function for a conserved condensate at unique membrane interfaces.

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Carl Tryggers Foundation 15, 17:336

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European Union 872969

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Vetenskapsradet (VR) research council 21679000

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FORMAS research council 22924-000

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Helge Ax:son Johnsons stiftelse F19-0419

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Hellenic Foundation of Research and Innovation 06526

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European Research Council 833867

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Ministerio de Ciencia e Innovación PID2020-119737GA-I00

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