Molecular mechanism for inhibition of a critical component in the Arabidopsis thaliana abscisic acid signal transduction pathways, SnRK2.6, by protein phosphatase ABI1.

TitleMolecular mechanism for inhibition of a critical component in the Arabidopsis thaliana abscisic acid signal transduction pathways, SnRK2.6, by protein phosphatase ABI1.
Publication TypeJournal Article
Year of Publication2012
AuthorsXie, T, Ren, R, Zhang, Y-yuan, Pang, Y, Yan, C, Gong, X, He, Y, Li, W, Miao, D, Hao, Q, Deng, H, Wang, Z, Wu, J-W, Yan, N
JournalJ Biol Chem
Volume287
Issue1
Pagination794-802
Date Published2012 Jan 02
ISSN1083-351X
KeywordsAbscisic Acid, Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Crystallography, X-Ray, Enzyme Activation, Models, Molecular, Molecular Sequence Data, Phosphoprotein Phosphatases, Phosphorylation, Protein Kinases, Protein Structure, Tertiary, Sequence Deletion, Signal Transduction
Abstract

Subclass III SnRK2s (SnRK2.6/2.3/2.2) are the key positive regulators of abscisic acid (ABA) signal transduction in Arabidopsis thaliana. The kinases, activated by ABA or osmotic stress, phosphorylate stress-related transcription factors and ion channels, which ultimately leads to the protection of plants from dehydration or high salinity. In the absence of stressors, SnRK2s are subject to negative regulation by group A protein phosphatase type 2Cs (PP2C), whereas the underlying molecular mechanism remains to be elucidated. Here we report the crystal structure of the kinase domain of SnRK2.6 at 2.6-Å resolution. Structure-guided biochemical analyses identified two distinct interfaces between SnRK2.6 and ABI1, a member of group A PP2Cs. Structural modeling suggested that the two interfaces lock SnRK2.6 and ABI1 in an orientation such that the activation loop of SnRK2.6 is posited to the catalytic site of ABI1 for dephosphorylation. These studies revealed the molecular basis for PP2Cs-mediated inhibition of SnRK2s and provided important insights into the downstream signal transduction of ABA.

DOI10.1074/jbc.M111.313106
Alternate JournalJ. Biol. Chem.
PubMed ID22090030
PubMed Central IDPMC3249133