EC Number   |
General Information |
Reference |
|---|
   2.1.1.278 | evolution |
the enzyme belongs to the protein family of SABATH methyltransferases, ten genes encode isozymes PaSABATH1-10. Five of the PaSABATH isozymes (PaSABATH3, PaSABATH6, PaSABATH7, PaSABATH8, and PaSABATH9) do not show activity with any of the four substrates, i.e. indole-3-acetic acid, jasmonic acid, giberellic acid A3, and salicylic acid, the other five of the PaSABATHs each show activity with one or more of the four substrates. PaSABATH1 has the highest level of specific activity with indole-3-acetic acid and is renamed as PaIAMT (EC 2.1.1.278). PaSABATH2 has the highest level of specific activity with salicylic acid and is designated as PaSAMT (EC 2.1.1.274). For comparison, PaSAMT is also assayed with two compounds of similar structure benzoic acid and anthranilic acid (cf. EC 2.1.1.273). While PaSAMT has no activity with anthranilic acid, its activity with benzoic acid is approximately 8% of that with salicylic acid. PaSABATH4, PaSABATH5 and PaSABATH10 show the highest level of specific activity with jasmonic acid and are renamed PaJAMT1, PaJAMT2, and PaJAMT3, respectively (EC 2.1.1.141). Their products are confirmed to be methyljasmonate |
757941 |
| 2.1.1.278 | evolution |
the enzyme belongs to the SABATH family, phylogenetic analysis and tree, detailed overview. Twenty-eight Populus SABATH genes are divided into three classes with distinct divergences in their gene structure, expression responses to abiotic stressors and enzymatic properties of encoded proteins. Populus class I SABATH proteins convert indole-3-acetic acid (IAA) to methyl-IAA, class II SABATH proteins convert benzoic acid (BA) and salicylic acid (SA) to methyl-BA and methyl-SA, while class III SABATH proteins convert farnesoic acid (FA) to methyl-FA. Populus class I SABATH gene (PtSABATH1) is grouped into clade I, Populus contains only one class I SABATH gene (PtSABATH1) |
757984 |
| 2.1.1.278 | malfunction |
overexpression of IAMT1 causes a decrease in auxin signalling. Reduction of indole-3-acetic acid methyltransferase activity compensates for high-temperature male sterility in Arabidopsis thaliana. Attenuation of IAMT1 activity promotes fertilization and enhances thermotolerance. The iamt1 mutant shows increased auxin signalling in funiculi, which correlated with a higher growth rate of wild-type pollen in contact with mutant ovaries and premature ovule fertilization. While the production of seeds per fruit is similar in the wild-type and the mutant at 20°C, exposure to 29°C causes a more severe decrease in fertility in the wild-type than in the mutant. Loss of IAMT1 activity is also associated with the production of more nodes after flowering and higher tolerance of the shoot apical meristem to higher temperatures. As a consequence, the productivity of the iamt1 mutant under higher temperatures is more than double of that of the wild-type, with almost no apparent trade-off |
757960 |
| 2.1.1.278 | metabolism |
expression patterns of Populus SABATH genes under normal growth conditions and abiotic stress, overview |
757984 |
| 2.1.1.278 | more |
a structural model for PaIAMTis generated to understand the origin of substrate specificity of PaSABATH methyltransferase. The active site of the PaIAMT model is superposed with that of the X-ray structure of IAMT (PDB ID 3B5I). The substrate indole-3-acetic acid (IAA) is docked into the active site in such way that its carboxyl moiety is located at a suitable position for accepting the methyl group from SAM (AdoMet). The active site of the enzymes is able to accommodate IAA in a reactive configuration. The enzyme has relatively high specificity for IAA. This is in contrast to docking jasmonate (JA) into the active site. When JA is docked into the active sites with the carboxyl moiety located at the suitable position for accepting the methyl group, the side chain of JA made steric clashes with some of the active site residues (F267 and L266 from PaIAMT), and the active site is therefore not able to accommodate JA for the methyl transfer |
757941 |
| 2.1.1.278 | physiological function |
of Populus SABATH enzymes, only PtSABATH1 has high activity towards indole-3-acetic acid (IAA), and can convert IAA to methyl-IAA, indicating that PtSABATH1 might play an important role in auxin homeostasis |
757984 |
| 2.1.1.278 | physiological function |
plant hormone auxin induces temperature tolerance to pollen. Methylation of indole-3-acetic acid (IAA) by indole-3-acetic acid methyltransferase has been shown to participate in auxin homeostasis. Methyl-IAA (Me-IAA) is an inactive form of IAA |
757960 |
| 2.1.1.278 | physiological function |
the enzyme is found in plants and is important for regulation of the plant hormone (indol-3-yl)acetate. The product, methyl (indol-3-yl)acetate is inactive as hormone |
723396 |
| 2.1.1.278 | physiological function |
the enzyme is involved in development of root and leaf in poplar and plays a role in wood formation |
726115 |
| 2.1.1.278 | physiological function |
the enzyme regulated leaf development. Overexpression of isoform IAMT1 in abaxial layers results in epinastic leaf phenotypes |
726158 |
