New paper from the Sprunck lab: ARO proteins delimit ROP signaling in tip growing cells. Now published in Nature Plants.

ARMADILLO REPEAT ONLY proteins confine Rho GTPase signaling to polar growth sites.

Nature Plants 6, 1275-1288

Ivan Kulich, Frank Vogler, Andrea Bleckmann, Philipp Cyprys, Maria Lindemeier, Ingrid Fuchs, Laura Krassini, Thomas Schubert, Jens Steinbrenner, Jim Beynon, Pascal Falter-Braun, Gernot Längst, Thomas Dresselhaus, and Stefanie Sprunck.

Polar growth requires the precise tuning of Rho GTPase signalling at distinct plasma membrane domains. The activity of Rho of plant (ROP) GTPases is regulated by the opposing action of guanine nucleotide-exchange factors (GEFs) and GTPase-activating proteins (GAPs). Whereas plant-specific ROPGEFs have been shown to be embedded in higher-level regulatory mechanisms involving membrane-bound receptor-like kinases, the regulation of GAPs has remained enigmatic. Here, we show that three ArabidopsisARMADILLO REPEAT ONLY (ARO) proteins are essential for the stabilization of growth sites in root hair cells and trichomes. AROs interact with ROP1 enhancer GAPs (RENGAPs) and bind to the plasma membrane via a conserved polybasic region at the ARO amino terminus. The ectopic spreading of ROP2 in aro2/3/4 mutant root hair cells and the preferential interaction of AROs with active ROPs and anionic phospholipids suggests that AROs recruit RENGAPs into complexes with ROPs to confine ROP signalling to distinct membrane regions.

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