Single Amino Acid Alteration between Valine and Isoleucine Determines the Distinct Pyrabactin Selectivity by PYL1 and PYL2

Abscisic acid (ABA) is one of the most important phytohormones in plant. PYL proteins were identified to be ABA receptors in Arabidopsis thaliana. Despite the remarkably high degree of sequence similarity, PYL1 and PYL2 exhibit distinct responses toward pyrabactin, an ABA agonist. PYL1 inhibits prot...

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Published in:The Journal of biological chemistry 2010-09, Vol.285 (37), p.28953-28958
Main Authors: Yuan, Xiaoqiu, Yin, Ping, Hao, Qi, Yan, Chuangye, Wang, Jiawei, Yan, Nieng
Format: Article
Language:English
Subjects:
ABA Receptor
ABA Signaling
Abscisic Acid
Abscisic Acid - agonists
Abscisic Acid - chemistry
Abscisic Acid - metabolism
Amino Acid
Arabidopsis - chemistry
Arabidopsis - metabolism
Arabidopsis Proteins - chemistry
Arabidopsis Proteins - metabolism
Crystal Structure
Crystallography, X-Ray
Isoleucine - chemistry
Isoleucine - metabolism
Ligand-binding Protein
Plant
Plant Biology
Protein Structure, Tertiary
PYL Proteins
Pyrabactin
Receptor Regulation
Receptors, Cell Surface - chemistry
Receptors, Cell Surface - metabolism
Signal Transduction
Valine - chemistry
Valine - metabolism
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Summary:Abscisic acid (ABA) is one of the most important phytohormones in plant. PYL proteins were identified to be ABA receptors in Arabidopsis thaliana. Despite the remarkably high degree of sequence similarity, PYL1 and PYL2 exhibit distinct responses toward pyrabactin, an ABA agonist. PYL1 inhibits protein phosphatase type 2C upon binding of pyrabactin. In contrast, PYL2 appears relatively insensitive to this compound. The crystal structure of pyrabactin-bound PYL1 revealed that most of the PYL1 residues involved in pyrabactin binding are conserved, hence failing to explain the selectivity of pyrabactin for PYL1 over PYL2. To understand the molecular basis of pyrabactin selectivity, we determined the crystal structure of PYL2 in complex with pyrabactin at 1.64 Å resolution. Structural comparison and biochemical analyses demonstrated that one single amino acid alteration between a corresponding valine and isoleucine determines the distinct pyrabactin selectivity by PYL1 and PYL2. These characterizations provide an important clue to dissecting the redundancy of PYL proteins.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M110.160192