4l39
Crystal structure of GH3.12 from Arabidopsis thaliana in complex with AMPCPP and salicylate
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 PubMedThe combination of protein crystallography and small-angle X-ray scattering (SAXS) provides a powerful method to investigate changes in protein conformation. These complementary structural techniques were used to probe the solution structure of the apo and the ligand-bound forms of the Arabidopsis thaliana acyl acid-amido synthetase GH3.12. This enzyme is part of the extensive GH3 family and plays a critical role in the regulation of plant hormones through the formation of amino-acid-conjugated hormone products via an ATP-dependent reaction mechanism. The enzyme adopts two distinct C-terminal domain orientations with `open' and `closed' active sites. Previous studies suggested that ATP only binds in the open orientation. Here, the X-ray crystal structure of GH3.12 is presented in the closed conformation in complex with the nonhydrolysable ATP analogue AMPCPP and the substrate salicylate. Using on-line HPLC purification combined with SAXS measurements, the most likely apo and ATP-bound protein conformations in solution were determined. These studies demonstrate that the C-terminal domain is flexible in the apo form and favours the closed conformation upon ATP binding. In addition, these data illustrate the efficacy of on-line HPLC purification integrated into the SAXS sample-handling environment to reliably monitor small changes in protein conformation through the collection of aggregate-free and highly redundant data. Determination of the GH3.12 protein conformation through HPLC-integrated SAXS measurements combined with X-ray crystallography.,Round A, Brown E, Marcellin R, Kapp U, Westfall CS, Jez JM, Zubieta C Acta Crystallogr D Biol Crystallogr. 2013 Oct;69(Pt 10):2072-80. doi:, 10.1107/S0907444913019276. Epub 2013 Sep 20. PMID:24100325[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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