6oms
From Proteopedia
Arabidopsis GH3.12 with Chorismate
Structural highlights
FunctionGH312_ARATH Catalyzes the conjugation of specific amino acids (e.g. Glu and possibly His, Lys, and Met) to their preferred acyl substrates (e.g. 4-substituted benzoates), in a magnesium ion- and ATP-dependent manner. Can use 4-substituted benzoates such as 4-aminobenzoate (pABA), 4-fluorobenzoate and 4-hydroxybenzoate (4-HBA), and, to a lesser extent, benzoate, vanillate and trans-cinnamate, but not 2-substituted benzoates and salicylic acid (SA), as conjugating acyl substrates. Involved in both basal and induced resistance in a SA-dependent manner. Confers resistance to virulent and avirulent pathogens (at least bacteria and oomycetes), and promotes SA glucosides accumulation. Required for the establishment of hyper-sensitive response (HR) upon incompatible interaction and subsequent systemic acquired resistance (SAR).[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedTo modulate responses to developmental or environmental cues, plants use Gretchen Hagen 3 (GH3) acyl acid amido synthetases to conjugate an amino acid to a plant hormone, a reaction that regulates free hormone concentration and downstream responses. The model plant Arabidopsis thaliana has 19 GH3 proteins, of which 9 have confirmed biochemical functions. One Brassicaceae-specific clade of GH3 proteins was predicted to use benzoate as a substrate and includes AtGH3.7 and AtGH3.12/PBS3. Previously identified as a 4-hydroxybenzoic acid-glutamate synthetase, AtGH3.12/PBS3 influences pathogen defense responses through salicylic acid. Recent work has shown that AtGH3.12/PBS3 uses isochorismate as a substrate, forming an isochorismate-glutamate conjugate that converts into salicylic acid. Here, we show that AtGH3.7 and AtGH3.12/PBS3 can also conjugate chorismate, a precursor of aromatic amino acids and salicylic acid, to cysteine and glutamate, respectively. The X-ray crystal structure of AtGH3.12/PBS3 in complex with AMP and chorismate at 1.94 A resolution, along with site-directed mutagenesis, revealed how the active site potentially accommodates this substrate. Examination of Arabidopsis knockout lines indicated that the gh3.7 mutants do not altered growth and no increased susceptibility to the pathogen Pseudomonas syringae, unlike gh3.12 mutants, which ere more susceptible than wild-type plants, as was the gh3.7/gh3.12 double mutant. The findings of our study suggest that GH3 proteins can use metabolic precursors of aromatic amino acids as substrates. Brassicaceae-specific Gretchen Hagen 3 acyl acid amido synthetases conjugate amino acids to chorismate, a precursor of aromatic amino acids and salicylic acid.,Holland CK, Westfall CS, Schaffer JE, De Santiago A, Zubieta C, Alvarez S, Jez JM J Biol Chem. 2019 Oct 1. pii: RA119.009949. doi: 10.1074/jbc.RA119.009949. PMID:31575658[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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