期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：20
页码：11771-11776
DOI：10.1073/pnas.2034853100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SOS2 (salt overly sensitive 2) is a serine/threonine protein kinase required for salt tolerance in Arabidopsis thaliana. In this study, we identified the protein phosphatase 2C ABI2 (abscisic acid-insensitive 2) as a SOS2-interacting protein. Deletion analysis led to the discovery of a novel protein domain of 37 amino acid residues, designated as the protein phosphatase interaction (PPI) motif, of SOS2 that is necessary and sufficient for interaction with ABI2. The PPI motif is conserved in protein kinases of the SOS2 family (i.e., protein kinase S, PKS) and in the DNA damage repair and replication block checkpoint kinase, Chk1, from various organisms including humans. Mutations in the conserved amino acid residues in the PPI motif abolish the interaction of SOS2 with ABI2. We also identified a protein kinase interaction domain in ABI2 and examined the interaction specificity between PKS and the ABI phosphatases. We found that some PKSs interact strongly with ABI2 whereas others interact preferentially with ABI1. The interaction between SOS2 and ABI2 was disrupted by the abi2-1 mutation, which causes increased tolerance to salt shock and abscisic acid insensitivity in plants. Our results establish the PPI motif and the protein kinase interaction domain as novel protein interaction domains that mediate the binding between the SOS2 family of protein kinases and the ABI1/2 family of protein phosphatases.
