1M6E
CRYSTAL STRUCTURE OF SALICYLIC ACID CARBOXYL METHYLTRANSFERASE (SAMT)
Summary for 1M6E
| Entry DOI | 10.2210/pdb1m6e/pdb |
| Descriptor | S-adenosyl-L-methionine:salicylic acid carboxyl methyltransferase, LUTETIUM (III) ION, S-ADENOSYL-L-HOMOCYSTEINE, ... (5 entities in total) |
| Functional Keywords | rossmann fold, protein-small molecule complex, transferase |
| Biological source | Clarkia breweri |
| Total number of polymer chains | 1 |
| Total formula weight | 41028.51 |
| Authors | Zubieta, C.,Ross, J.R.,Koscheski, P.,Yang, Y.,Pichersky, E.,Noel, J.P. (deposition date: 2002-07-16, release date: 2003-09-09, Last modification date: 2024-02-14) |
| Primary citation | Zubieta, C.,Ross, J.R.,Koscheski, P.,Yang, Y.,Pichersky, E.,Noel, J.P. Structural Basis for Substrate Recognition in The Salicylic Acid Carboxyl Methyltransferase Family Plant Cell, 15:1704-1716, 2003 Cited by PubMed Abstract: Recently, a novel family of methyltransferases was identified in plants. Some members of this newly discovered and recently characterized methyltransferase family catalyze the formation of small-molecule methyl esters using S-adenosyl-L-Met (SAM) as a methyl donor and carboxylic acid-bearing substrates as methyl acceptors. These enzymes include SAMT (SAM:salicylic acid carboxyl methyltransferase), BAMT (SAM:benzoic acid carboxyl methyltransferase), and JMT (SAM:jasmonic acid carboxyl methyltransferase). Moreover, other members of this family of plant methyltransferases have been found to catalyze the N-methylation of caffeine precursors. The 3.0-A crystal structure of Clarkia breweri SAMT in complex with the substrate salicylic acid and the demethylated product S-adenosyl-L-homocysteine reveals a protein structure that possesses a helical active site capping domain and a unique dimerization interface. In addition, the chemical determinants responsible for the selection of salicylic acid demonstrate the structural basis for facile variations of substrate selectivity among functionally characterized plant carboxyl-directed and nitrogen-directed methyltransferases and a growing set of related proteins that have yet to be examined biochemically. Using the three-dimensional structure of SAMT as a guide, we examined the substrate specificity of SAMT by site-directed mutagenesis and activity assays against 12 carboxyl-containing small molecules. Moreover, the utility of structural information for the functional characterization of this large family of plant methyltransferases was demonstrated by the discovery of an Arabidopsis methyltransferase that is specific for the carboxyl-bearing phytohormone indole-3-acetic acid. PubMed: 12897246DOI: 10.1105/tpc.014548 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (3 Å) |
Structure validation
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