Inverse regulation of SOS1 and HKT1 protein localization and stability by SOS3/CBL4 in Arabidopsis thaliana.
Proc Natl Acad Sci U S A
; 121(9): e2320657121, 2024 Feb 27.
Article
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| ID: mdl-38386704
ABSTRACT
To control net sodium (Na+) uptake, Arabidopsis plants utilize the plasma membrane (PM) Na+/H+ antiporter SOS1 to achieve Na+ efflux at the root and Na+ loading into the xylem, and the channel-like HKT1;1 protein that mediates the reverse flux of Na+ unloading off the xylem. Together, these opposing transport systems govern the partition of Na+ within the plant yet they must be finely co-regulated to prevent a futile cycle of xylem loading and unloading. Here, we show that the Arabidopsis SOS3 protein acts as the molecular switch governing these Na+ fluxes by favoring the recruitment of SOS1 to the PM and its subsequent activation by the SOS2/SOS3 kinase complex under salt stress, while commanding HKT1;1 protein degradation upon acute sodic stress. SOS3 achieves this role by direct and SOS2-independent binding to previously unrecognized functional domains of SOS1 and HKT1;1. These results indicate that roots first retain moderate amounts of salts to facilitate osmoregulation, yet when sodicity exceeds a set point, SOS3-dependent HKT1;1 degradation switches the balance toward Na+ export out of the root. Thus, SOS3 functionally links and co-regulates the two major Na+ transport systems operating in vascular plants controlling plant tolerance to salinity.
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Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Arabidopsis
/
Proteínas de Arabidopsis
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2024
Tipo del documento:
Article
País de afiliación:
España
Pais de publicación:
Estados Unidos