Inverse regulation of SOS1 and HKT1 protein localization and stability by SOS3/CBL4 in Arabidopsis thaliana

• DOI: 10.1073/pnas.2320657121
• Publication Date: 2024-02-22T18:48:56Z
• Authors: Francisco Gámez-A...; Hee Jin Park; Elena García; Rashid Aman; Irene Villalta; Natalia Raddatz; Raul Carranco; Akhtar Ali; Zahir Ali; Shah Zareen; Anna De Luca; Eduardo O. Leidi; Miguel Daniel-Mozo; Zheng-Yi Xu; Armando Albert; Woe-Yeon Kim; Jose M. Pardo; Clara Sánchez-Rod...; Dae-Jin Yun; Francisco J. Quin...
• Keywords: 580; salinity; sodium transport; SOS pathway; HKT1; Arabidopsis; SOS pathway; Arabidopsis; sodium transport; HKT1; Biological Sciences; salinity

To control net sodium (Na + ) uptake, Arabidopsis plants utilize the plasma membrane (PM) Na /H antiporter SOS1 to achieve efflux at root and loading into xylem, channel-like HKT1;1 protein that mediates reverse flux of unloading off xylem. Together, these opposing transport systems govern partition within plant yet they must be finely co-regulated prevent a futile cycle xylem unloading. Here, we show SOS3 acts as molecular switch governing fluxes by favoring recruitment PM its subsequent activation SOS2/SOS3 kinase complex under salt stress, while commanding degradation upon acute sodic stress. achieves this role direct SOS2-independent binding previously unrecognized functional domains HKT1;1. These results indicate roots first retain moderate amounts salts facilitate osmoregulation, when sodicity exceeds set point, SOS3-dependent switches balance toward export out root. Thus, functionally links co-regulates two major operating in vascular controlling tolerance salinity.