Functional divergence of plant SCAR/WAVE proteins is determined by intrinsically disordered regions.

Brumm, Sabine; Gavrin, Aleksandr; Macleod, Matthew; Chesneau, Guillaume; Usländer, Annika; Schornack, Sebastian · Sci Adv · 2025

basic_science · Level V

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Abstract

Dynamic actin cytoskeleton reorganization enables plant developmental processes requiring polarized transport such as root hair and leaf trichome formation. The SCAR/WAVE complex plays a crucial role in regulating these dynamics through ARP2/3-mediated actin branching. <i>SCAR/WAVE</i> genes occur as small families across a wide range of plant species, but whether and how they fulfill different functions remains unclear. We use a systematic chimera approach to define the differential functionality of two closely related <i>Medicago truncatula</i> SCAR proteins in plant development. We show that SCAR/WAVE contribution to <i>M. truncatula</i> root hair or <i>Arabidopsis thaliana</i> trichome formation is dependent on two central intrinsically disordered regions (IDRs). Differential functionalities of <i>M. truncatula</i> SCAR proteins were furthermore associated with the presence/absence of a 42-amino acid sequence within the IDR that affected protein stability. Through uncovering a molecular basis for functional differences, we advance our understanding of plant SCAR/WAVE complexes.

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