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Arabidopsis thaliana GH3.15 acyl acid amido synthetase has a highly specific substrate preference for the auxin precursor indole-3-butyric acid.
J Biol Chem. 2018 03 23; 293(12):4277-4288.JB

Abstract

Various phytohormones control plant growth and development and mediate biotic and abiotic stress responses. Gretchen Hagen 3 (GH3) acyl acid amido synthetases are plant enzymes that typically conjugate amino acids to indole-3-acetic acid (IAA) or jasmonic acid (JA) to inactivate or activate these phytohormones, respectively; however, the physiological and biological roles of many of these enzymes remain unclear. Using a biochemical approach, we found that the Arabidopsis thaliana GH3.15 (AtGH3.15) preferentially uses indole-3-butyric acid (IBA) and glutamine as substrates. The X-ray crystal structure of the AtGH3.15·AMP complex, modeling of IBA in the active site, and biochemical analysis of site-directed mutants provide insight on active site features that lead to AtGH3.15's preference for IBA. Assay-based in planta analysis of AtGH3.15-overexpressing lines indicated that their root elongation and lateral root density were resistant to IBA treatment but not to treatment with either IAA or JA. These findings suggest that AtGH3.15 may play a role in auxin homeostasis by modulating the levels of IBA for peroxisomal conversion to IAA. Analysis of AtGH3.15 promoter-driven yellow fluorescent protein reporter lines revealed that AtGH3.15 is expressed at significant levels in seedlings, roots, and parts of the siliques. We conclude that AtGH3.15 is unique in the GH3 protein family for its role in modifying IBA in auxin homeostasis and that it is the first GH3 protein shown to primarily modify a plant growth regulator other than IAA and JA.

Authors+Show Affiliations

From the Department of Biology, Washington University, St. Louis, Missouri 63130 and.From the Department of Biology, Washington University, St. Louis, Missouri 63130 and.the Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68588.From the Department of Biology, Washington University, St. Louis, Missouri 63130 and jjez@wustl.edu.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

29462792

Citation

Sherp, Ashley M., et al. "Arabidopsis Thaliana GH3.15 Acyl Acid Amido Synthetase Has a Highly Specific Substrate Preference for the Auxin Precursor Indole-3-butyric Acid." The Journal of Biological Chemistry, vol. 293, no. 12, 2018, pp. 4277-4288.
Sherp AM, Westfall CS, Alvarez S, et al. Arabidopsis thaliana GH3.15 acyl acid amido synthetase has a highly specific substrate preference for the auxin precursor indole-3-butyric acid. J Biol Chem. 2018;293(12):4277-4288.
Sherp, A. M., Westfall, C. S., Alvarez, S., & Jez, J. M. (2018). Arabidopsis thaliana GH3.15 acyl acid amido synthetase has a highly specific substrate preference for the auxin precursor indole-3-butyric acid. The Journal of Biological Chemistry, 293(12), 4277-4288. https://doi.org/10.1074/jbc.RA118.002006
Sherp AM, et al. Arabidopsis Thaliana GH3.15 Acyl Acid Amido Synthetase Has a Highly Specific Substrate Preference for the Auxin Precursor Indole-3-butyric Acid. J Biol Chem. 2018 03 23;293(12):4277-4288. PubMed PMID: 29462792.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Arabidopsis thaliana GH3.15 acyl acid amido synthetase has a highly specific substrate preference for the auxin precursor indole-3-butyric acid. AU - Sherp,Ashley M, AU - Westfall,Corey S, AU - Alvarez,Sophie, AU - Jez,Joseph M, Y1 - 2018/02/08/ PY - 2018/01/19/received PY - 2018/02/05/revised PY - 2018/2/21/pubmed PY - 2019/1/15/medline PY - 2018/2/21/entrez KW - Arabidopsis thaliana KW - X-ray crystallography KW - auxin KW - auxin homeostasis KW - enzyme kinetics KW - indole-3-butyric acid KW - jasmonic acid KW - phytohormone KW - plant hormone SP - 4277 EP - 4288 JF - The Journal of biological chemistry JO - J Biol Chem VL - 293 IS - 12 N2 - Various phytohormones control plant growth and development and mediate biotic and abiotic stress responses. Gretchen Hagen 3 (GH3) acyl acid amido synthetases are plant enzymes that typically conjugate amino acids to indole-3-acetic acid (IAA) or jasmonic acid (JA) to inactivate or activate these phytohormones, respectively; however, the physiological and biological roles of many of these enzymes remain unclear. Using a biochemical approach, we found that the Arabidopsis thaliana GH3.15 (AtGH3.15) preferentially uses indole-3-butyric acid (IBA) and glutamine as substrates. The X-ray crystal structure of the AtGH3.15·AMP complex, modeling of IBA in the active site, and biochemical analysis of site-directed mutants provide insight on active site features that lead to AtGH3.15's preference for IBA. Assay-based in planta analysis of AtGH3.15-overexpressing lines indicated that their root elongation and lateral root density were resistant to IBA treatment but not to treatment with either IAA or JA. These findings suggest that AtGH3.15 may play a role in auxin homeostasis by modulating the levels of IBA for peroxisomal conversion to IAA. Analysis of AtGH3.15 promoter-driven yellow fluorescent protein reporter lines revealed that AtGH3.15 is expressed at significant levels in seedlings, roots, and parts of the siliques. We conclude that AtGH3.15 is unique in the GH3 protein family for its role in modifying IBA in auxin homeostasis and that it is the first GH3 protein shown to primarily modify a plant growth regulator other than IAA and JA. SN - 1083-351X UR - https://www.unboundmedicine.com/medline/citation/29462792/Arabidopsis_thaliana_GH3_15_acyl_acid_amido_synthetase_has_a_highly_specific_substrate_preference_for_the_auxin_precursor_indole_3_butyric_acid_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(20)39802-1 DB - PRIME DP - Unbound Medicine ER -