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Phytochemistry. 2018 May;149:146-154. doi: 10.1016/j.phytochem.2018.02.010. Epub 2018 Mar 2.

Biochemical characterization in Norway spruce (Picea abies) of SABATH methyltransferases that methylate phytohormones.

Author information

1
Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA; Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
2
Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA.
3
Shandong Agricultural University, Chemistry and Material Science Faculty, Tai'an, 271018 Shandong, China.
4
College of Life Sciences, Shaanxi Normal University, Xi'an, China.
5
Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA.
6
Department of Biochemical, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA; UT/ORNL Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
7
Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA. Electronic address: fengc@utk.edu.

Abstract

Indole-3-acetic acid (IAA), gibberellins (GAs), salicylic acid (SA) and jasmonic acid (JA) exist in methyl ester forms in plants in addition to their free acid forms. The enzymes that catalyze methylation of these carboxylic acid phytohormones belong to a same protein family, the SABATH methyltransferases. While the genes encoding these enzymes have been isolated from a small number of flowering plants, little is known about their occurrence and evolution in non-flowering plants. Here, we report the systematic characterization of the SABATH family from Norway spruce (Picea abies), a gymnosperm. The Norway spruce genome contains ten SABATH genes (PaSABATH1-10). Full-length cDNA for each of the ten PaSABATH genes was cloned and expressed in Escherichia coli. Recombinant PaSABATHs were tested for activity with IAA, GA, SA, and JA. Among the ten PaSABATHs, five had activity with one or more of the four substrates. PaSABATH1 and PaSABATH2 had the highest activities with IAA and SA, respectively. PaSABATH4, PaSABATH5 and PaSABATH10 all had JA as a preferred substrate but with notable differences in biochemical properties. The structural basis of PaSABATHs in discriminating various phytohormone substrates was inferred based on structural models of the enzyme-substrate complexes. The phylogeny of PaSABATHs with selected SABATHs from other plants implies that the enzymes methylating IAA are conserved in seed plants whereas the enzymes methylating JA and SA have independent evolution in gymnosperms and angiosperms.

KEYWORDS:

Jasmonic acid; Norway spruce; Picea abies; SABATH methyltransferase

PMID:
29501924
DOI:
10.1016/j.phytochem.2018.02.010
[Indexed for MEDLINE]

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