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Sterlin Y, Pri-Tal O, Zimran G, Park SY, Ben-Ari J, Kourelis J, Verstraeten I, Gal M, Cutler SR, Mosquna A. Optimized small-molecule pull-downs define MLBP1 as an acyl-lipid-binding protein. Plant J 2019; 98:928-941. [PMID: 30735592 DOI: 10.1111/tpj.14272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 01/02/2019] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
Abscisic acid (ABA) receptors belong to the START domain superfamily, which encompasses ligand-binding proteins present in all kingdoms of life. START domain proteins contain a central binding pocket that, depending on the protein, can couple ligand binding to catalytic, transport or signaling functions. In Arabidopsis, the best characterized START domain proteins are the 14 PYR/PYL/RCAR ABA receptors, while the other members of the superfamily do not have assigned ligands. To address this, we used affinity purification of biotinylated proteins expressed transiently in Nicotiana benthamiana coupled to untargeted LC-MS to identify candidate binding ligands. We optimized this method using ABA-PYL interactions and show that ABA co-purifies with wild-type PYL5 but not a binding site mutant. The Kd of PYL5 for ABA is 1.1 μm, which suggests that the method has sufficient sensitivity for many ligand-protein interactions. Using this method, we surveyed a set of 37 START domain-related proteins, which resulted in the identification of ligands that co-purified with MLBP1 (At4G01883) or MLP165 (At1G35260). Metabolite identification and the use of authentic standards revealed that MLBP1 binds to monolinolenin, which we confirmed using recombinant MLBP1. Monolinolenin also co-purified with MLBP1 purified from transgenic Arabidopsis, demonstrating that the interaction occurs in a native context. Thus, deployment of this relatively simple method allowed us to define a protein-metabolite interaction and better understand protein-ligand interactions in plants.
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Affiliation(s)
- Yelena Sterlin
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, the Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Oded Pri-Tal
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, the Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Gil Zimran
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, the Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Sang-Youl Park
- Department of Botany and Plant Sciences, Center for Plant Cell Biology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Julius Ben-Ari
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, the Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Jiorgos Kourelis
- Department of Botany and Plant Sciences, Center for Plant Cell Biology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Inge Verstraeten
- Department of Botany and Plant Sciences, Center for Plant Cell Biology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Maayan Gal
- Biochemistry Department, MIGAL-Galilee Research Institute, Kiryat-Shmona , 11016, Israel
- Faculty of Sciences and Technology, Tel-Hai Academic College, Upper Galilee, 1220800, Israel
| | - Sean R Cutler
- Department of Botany and Plant Sciences, Center for Plant Cell Biology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Assaf Mosquna
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, the Hebrew University of Jerusalem, Rehovot, 7610001, Israel
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Pri-Tal O, Shaar-Moshe L, Wiseglass G, Peleg Z, Mosquna A. Non-redundant functions of the dimeric ABA receptor BdPYL1 in the grass Brachypodium. Plant J 2017; 92:774-786. [PMID: 28891214 DOI: 10.1111/tpj.13714] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/31/2017] [Accepted: 09/04/2017] [Indexed: 05/05/2023]
Abstract
Abiotic stresses have severe detrimental effects on agricultural productivity worldwide. Abscisic acid (ABA) levels rise in response to abiotic stresses, and play a role in coordinating physiological responses. ABA elicits its effects by binding a family of soluble receptors, increasing affinity of the receptors to type 2C phosphatases (PP2Cs) leading to phosphatase inhibition. In the current study, we conducted a comprehensive analysis of the ABA signaling pathway in the cereal model grass Brachypodium distachyon. The Brachypodium genome encodes a family of 10 functionally conserved ABA receptors. The 10th in the series, BdPYL10, encodes a defective receptor and is likely a pseudogene. Combinatorial protein interaction assay further validated computational analysis, which grouped Brachypodium ABA receptors into three subfamilies, similarly to Arabidopsis classification. Brachypodium subfamily III receptors inhibited PP2C activity in vitro and complemented Arabidopsis quadruple (pyr1/pyl1/pyl2/pyl4) mutant. BdPYL1 T-DNA mutant exhibited clear ABA hyposensitivity phenotypes during seedling establishment and in mature plants. Single receptor predominance is in agreement with high transcriptional abundance of only a small Brachypodium ABA receptors subset, harboring the higher marginal significance of BdPYL1. Our findings suggest that unlike the highly redundant ABA core signaling components of Arabidopsis, Brachypodium encompasses a more compact and specialized ABA receptor apparatus. This organization may contribute to plant adaptations to ecological niches. These results lay the groundwork for targeting the prominent ABA receptors for stress perception in grasses, and reveal functional differences and commonalities between monocots and eudicots.
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Affiliation(s)
- Oded Pri-Tal
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Lidor Shaar-Moshe
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Gil Wiseglass
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Zvi Peleg
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Assaf Mosquna
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
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