Abstract
Our biochemical analyses of AtHOL1, which is involved in methyl halide emissions in Arabidopsis, and its isoforms designated AtHOL2 and AtHOL3 showed that the three recombinant AtHOL proteins could catalyze the S-adenosyl-L-methionine-dependent methylation of Cl-, Br-, I-, NCS-, and HS-. We were interested in the results indicating that Cl- methyltransferase activities of three recombinant proteins were very low whereas the NCS- methyltransferase activity of AtHOL1 was high. Analyses of the AtHOL1-disrupted mutant showed that AtHOL1 methylated NCS- produced in homogenized Arabidopsis tissues and CH3SCN was synthesized. Our results implied that NCS-was derived from indolyl-glucosinolates and S-adenosyl-L-methionine was rate determining for CH3SCN synthesis in homogenized tissues. Glucosinolate are defensive compound and when tissues are damaged, they are hydrolyzed by myrosinase. It was reported that indolyl-glucosinolate accumulated by the treatments of methyl jasmonate or elicitors from plant pathogens. The possible physiological roles of AtHOL1 will be discussed.
