Molecular basis for the selective and ABA-independent inhibition of PP2CA by PYL13. Author Wenqi Li, Li Wang, Xinlei Sheng, Chuangye Yan, Rui Zhou, Jing Hang, Ping Yin, Nieng Yan Publication Year 2013 Type Journal Article Abstract PYR1/PYL/RCAR family proteins (PYLs) are well-characterized abscisic acid (ABA) receptors. Among the 14 PYL members in Arabidopsis thaliana, PYL13 is ABA irresponsive and its function has remained elusive. Here, we show that PYL13 selectively inhibits the phosphatase activity of PP2CA independent of ABA. The crystal structure of PYL13-PP2CA complex, which was determined at 2.4 Å resolution, elucidates the molecular basis for the specific recognition between PP2CA and PYL13. In addition to the canonical interactions between PYLs and PP2Cs, an extra interface is identified involving an element in the vicinity of a previously uncharacterized CCCH zinc-finger (ZF) motif in PP2CA. Sequence blast identified another 56 ZF-containing PP2Cs, all of which are from plants. The structure also reveals the molecular determinants for the ABA irresponsiveness of PYL13. Finally, biochemical analysis suggests that PYL13 may hetero-oligomerize with PYL10. These two PYLs antagonize each other in their respective ABA-independent inhibitions of PP2Cs. The biochemical and structural studies provide important insights into the function of PYL13 in the stress response of plant and set up a foundation for future biotechnological applications of PYL13. Keywords Molecular Sequence Data, Protein Binding, Protein Structure, Tertiary, Crystallography, X-Ray, Amino Acid Sequence, Sequence Alignment, Sequence Homology, Amino Acid, Arabidopsis, Arabidopsis Proteins, Zinc Fingers, Abscisic Acid, Phosphoprotein Phosphatases Journal Cell Res Volume 23 Issue 12 Pages 1369-79 Date Published 2013 Dec ISSN Number 1748-7838 DOI 10.1038/cr.2013.143 Alternate Journal Cell Res PMCID PMC3847573 PMID 24165892 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML