Skip Navigation



Molecular Plant Advance Access published online on January 6, 2009
Molecular Plant, doi:10.1093/mp/ssn087
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
2/1/183    most recent
ssn087v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Fujii, H.
Right arrow Articles by Zhu, J.-K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2009. Published by the Molecular Plant Shanghai Editorial Office in association with Oxford University Press on behalf of CSPP and IPPE, SIBS, CAS.

An Autophosphorylation Site of the Protein Kinase SOS2 Is Important for Salt Tolerance in Arabidopsis

Hiroaki Fujii and Jian-Kang Zhu1

Department of Botany and Plant Sciences, 2150 Batchelor Hall, University of California, Riverside, CA 92521, USA

1 To whom correspondence should be addressed. E-mail jian-kang.zhu{at}ucr.edu, fax 951-827-7115, tel. 951-827-7117.

The protein kinase SOS2 (Salt Overly Sensitive 2) is essential for salt-stress signaling and tolerance in Arabidopsis. SOS2 is known to be activated by calcium-SOS3 and by phosphorylation at its activation loop. SOS2 is autophosphorylated in vitro, but the autophosphorylation site and its role in salt tolerance are not known. In this study, we identified an autophosphorylation site in SOS2 and analyzed its role in the responses of Arabidopsis to salt stress. Mass spectrometry analysis showed that Ser 228 of SOS2 is autophosphorylated. When this site was mutated to Ala, the autophosphorylation rate of SOS2 decreased. The substrate phosphorylation by the mutated SOS2 was also less than that by the wild-type SOS2. In contrast, changing Ser228 to Asp to mimic the autophosphorylation enhanced substrate phosphorylation by SOS2. Complementation tests in a sos2 mutant showed that the S228A but not the S228D mutation partially disrupted the function of SOS2 in salt tolerance. We also show that activation loop phosphorylation at Thr168 and autophosphorylation at Ser228 cannot substitute for each other, suggesting that both are required for salt tolerance. Our results indicate that Ser 228 of SOS2 is autophosphorylated and that this autophosphorylation is important for SOS2 function under salt stress.

Key Words: SOS2 • autophosphorylation • salt tolerance • protein kinase • Arabidopsis


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Plant CellHome page
H. Lin, Y. Yang, R. Quan, I. Mendoza, Y. Wu, W. Du, S. Zhao, K. S. Schumaker, J. M. Pardo, and Y. Guo
Phosphorylation of SOS3-LIKE CALCIUM BINDING PROTEIN8 by SOS2 Protein Kinase Stabilizes Their Protein Complex and Regulates Salt Tolerance in Arabidopsis
PLANT CELL, May 1, 2009; 21(5): 1607 - 1619.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.