4B2G

Crystal Structure of an Indole-3-Acetic Acid Amido Synthase from Vitis vinifera Involved in Auxin Homeostasis

Summary for 4B2G

• Entry DOI: 10.2210/pdb4b2g/pdb
• Descriptor: GH3-1 AUXIN CONJUGATING ENZYME, MALONATE ION, [(2S,3R,4R,5R)-5-(6-aminopurin-9-yl)-3,4-bis(oxidanyl)oxolan-2-yl] 2-(1H-indol-3-yl)ethyl hydrogen phosphate, ... (4 entities in total)
• Functional Keywords: signaling protein, ignaling protein, adenylate, amino acid conjugation, plant growth
• Biological source: VITIS VINIFERA (GRAPEVINE)
• Total number of polymer chains: 2
• Total formula weight: 138723.44

Authors

Peat, T.S.,Bottcher, C.,Newman, J.,Lucent, D.,Cowieson, N.,Davies, C. (deposition date: 2012-07-16, release date: 2012-12-19, Last modification date: 2024-05-08)

Primary citation

Peat, T.S.,Bottcher, C.,Newman, J.,Lucent, D.,Cowieson, N.,Davies, C.
Crystal Structure of an Indole-3-Acetic Acid Amido Synthetase from Grapevine Involved in Auxin Homeostasis.
Plant Cell, 24:4525-, 2012

PubMed Abstract: Auxins are important for plant growth and development, including the control of fruit ripening. Conjugation to amino acids by indole-3-acetic acid (IAA)-amido synthetases is an important part of auxin homeostasis. The structure of the auxin-conjugating Gretchen Hagen3-1 (GH3-1) enzyme from grapevine (Vitis vinifera), in complex with an inhibitor (adenosine-5'-[2-(1H-indol-3-yl)ethyl]phosphate), is presented. Comparison with a previously published benzoate-conjugating enzyme from Arabidopsis thaliana indicates that grapevine GH3-1 has a highly similar domain structure and also undergoes a large conformational change during catalysis. Mutational analyses and structural comparisons with other proteins have identified residues likely to be involved in acyl group, amino acid, and ATP substrate binding. Vv GH3-1 is a monomer in solution and requires magnesium ions solely for the adenlyation reaction. Modeling of IAA and two synthetic auxins, benzothiazole-2-oxyacetic acid (BTOA) and 1-naphthaleneacetic acid (NAA), into the active site indicates that NAA and BTOA are likely to be poor substrates for this enzyme, confirming previous enzyme kinetic studies. This suggests a reason for the increased effectiveness of NAA and BTOA as auxins in planta and provides a tool for designing new and effective auxins.

PubMed: 23136372
DOI: 10.1105/TPC.112.102921

Experimental method

X-RAY DIFFRACTION (2.4 Å)