A1 Refereed original research article in a scientific journal
Activation of the plasma membrane Na/H antiporter Salt-Overly-Sensitive 1 (SOS1) by phosphorylation of an auto-inhibitory C-terminal domain
Authors: Quintero, Francisco J.; Martinez-Atienza, Juliana; Villalta, Irene; Jiang, Xingyu; Kim, Woe-Yeon; Ali, Zhair; Fujii, Hiroaki; Mendoza, Imelda; Yun, Dae-Jin; Zhu, Jian-Kang; Pardo, Jose M.
Publisher: NATL ACAD SCIENCES
Publishing place: WASHINGTON
Publication year: 2011
Journal: Proceedings of the National Academy of Sciences of the United States of America
Journal name in source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Journal acronym: P NATL ACAD SCI USA
Volume: 108
Issue: 6
First page : 2611
Last page: 2616
Number of pages: 6
ISSN: 0027-8424
DOI: https://doi.org/10.1073/pnas.1018921108
The plasma membrane sodium/proton exchanger Salt-Overly-Sensitive 1 (SOS1) is a critical salt tolerance determinant in plants. The SOS2-SOS3 calcium-dependent protein kinase complex up-regulates SOS1 activity, but the mechanistic details of this crucial event remain unresolved. Here we show that SOS1 is maintained in a resting state by a C-terminal auto-inhibitory domain that is the target of SOS2-SOS3. The auto-inhibitory domain interacts intramolecularly with an adjacent domain of SOS1 that is essential for activity. SOS1 is relieved from auto-inhibition upon phosphorylation of the auto-inhibitory domain by SOS2-SOS3. Mutation of the SOS2 phosphorylation and recognition site impeded the activation of SOS1 in vivo and in vitro. Additional amino acid residues critically important for SOS1 activity and regulation were identified in a genetic screen for hypermorphic alleles.
