ROPGAP-dependent interaction between brassinosteroid and ROP2-GTPase signaling controls pavement cell shape in Arabidopsis

Abstract

Highlights d BIN2 interacts with and phosphorylates PHGAPs d PHGAPs are enriched in the anticlinal face of the pavement cell indenting regions d BIN2 phosphorylation of PHGAPs affects their turnover and localization d Brassinosteroids activate ROP2 in the lobes through PHGAP degradation

Arabidopsis pavement cell shape formation involves spatially confined ROPGAP regulators

“…BR-INSENSITIVE2 (BIN2) kinase-dependent PHGAP phosphorylation tied brassinosteroid (BR) to ROP signaling in pavement cell shaping via the regulation of PHGAP. 48 Previous studies also connected BR signaling, the cytoskeleton, and pavement cell expansion. 57,58 Based on mutant phenotype similarity and the interaction between PHGAPs and mitotic IQ67 family members during cell division, IQ67 DOMAIN 5 (IQD5) might be linking microtubules and PHGAPs.…”

“…The elevated levels of active ROP2 in phgap1-1phgap2-1 mutants, together with interaction studies, pointed to compromised inactivation of ROP2 (Figures 3 and S2). 27,35,48 During pavement cell morphogenesis, ROP2 and ROP6 activities require tightly controlled restriction to convex lobe and concave indentation regions, respectively, as overexpression of either ROP2 or ROP6 leads to the severe loss of pavement cell shape complexity. 11,15 Consequently, due to their antagonistic activities, the inactivation of ROP2 by PHGAPs should foster ROP6-mediated bundling of microtubules at indentations.…”

Mapping the adaptor protein complex interaction network in Arabidopsis identifies P34 as a common stability regulator

“…For P34 -inducible CRISPR editing experiments, seeds were germinated and grown directly on ½MS containing either DMSO or 10 µM β-estradiol at 22°C and a 16-h light/8-h dark photoperiod for 5, 7 or 9 days. Transgenic Arabidopsis lines expressing p35S:GFP/Col- 0 65 , pAP2S:AP2S-GFP/ap2s 15 , pMTV1:MTV1-GFP/Col-0 23 , pMTV1:MTV1-GFP/ap4b-1 23 , pAP4M:AP4M-GFP/ap4m-2 66 , pAP3B:AP3B-GFP/pat2-1 18 , pSYP61:SYP61-CFP 67 , pVHAa1-VHAa1-mRFP 68 , p35S:secRFP 51 , pPIN2:PIN2-GFP 37 , ap2m-2 16 have been previously described. Wild-type tobacco ( Nicotiana benthamiana ) plants were grown in the greenhouse under a normal 14-h light/10-h dark regime at 25°C.…”

ROP GTPase‐dependent polarity establishment during tip growth in plants

“…In general, RopGEFs promote ROP activation and membrane accumulation; RopGAPs restrict the active ROP domain (Feiguelman et al ., 2018). In plants, a noncanonical group of RopGAPs, the PLECKSTRIN HOMOLOGY (PH) domain‐containing RenGAPs (REN1 and PHGAP1/2 in Arabidopsis), also negatively regulate ROP localization: REN1 functions in the apical cytoplasm of pollen tubes to globally inhibit ROPs (Hwang et al ., 2008), while PHGAP1/2 restrict ROP localization at the plasma membrane in pavement cells (Lauster et al ., 2022; Zhang et al ., 2022). Interestingly, the membrane‐associated ARMADILLO REPEAT ONLY (ARO) proteins interact with REN1 and PHGAP1/2 to limit tip localization of ROPs in root hairs (Kulich et al ., 2020), suggesting the involvement of additional factors and complex interactions between ROP activity and membrane domain formation.…”