Characterization of three halide methyltransferases in Arabidopsis thaliana
Methyl chloride and methyl bromide, which contribute to the destruction of the stratospheric ozone layer, are mainly emitted from natural sources. It was recently reported that tropical and subtropical plants were the largest sources of methyl chloride. Furthermore, the involvement of the gene <i>HARMLESS TO OZONE LAYER (HOL)</i> in methyl halide emissions from <i>Arabidopsis thaliana</i> was demonstrated. However, neither the physiological significance of the methyl chloride emission nor the biochemical properties of HOL, denoted as AtHOL1 in our study, have been reported yet. We identified two additional isoforms-<i>AtHOL2</i> and <i>AtHOL3</i>-from <i>Arabidopsis</i> and characterized them together with <i>AtHOL1</i>. <i>AtHOL1</i> was ubiquitously expressed during development, and its expression level was the highest among the three. The phylogenetic tree suggested that AtHOL1 homologous proteins were distributed throughout the plant kingdom. Biochemical analyses showed that the three recombinant AtHOL proteins were functional and had distinct levels of the S-adenosyl-L-methionine-dependent methyltransferase activities. Although a study of <i>AtHOL1</i>-disrupted mutants had shown that <i>AtHOL1</i> primarily controlled the production of methyl halide, our study suggested that the activation of <i>AtHOL2</i> and <i>AtHOL3</i> genes also contribute to the methyl halide emissions from <i>Arabidopsis</i>.
- Plant biotechnology
Plant biotechnology 24(5), 503-506, 2007-12-01
Japanese Society for Plant Cell and Molecular Biology