TAILIEUCHUNG - Báo cáo khoa học: Cloning and expression of a tomato cDNA encoding a methyl jasmonate cleaving esterase

Jasmonic acid and its methyl ester are ubiquitous plant sig-nalling compounds necessary for the regulation of growth and development, as well as for the response of plants to environmental stress factors. To date, it is not clear whether methyl jasmonate itself acts as a signal or if its conversion to jasmonic acid is mandatory prior to the induction of a def-ense response. We have cloned a cDNA, encoding a methyl jasmonate-cleaving enzyme, from tomato cell suspension cultures. Sequence analysis revealed significant similarity to plant esterases and to (S)-hydroxynitrile lyases with ana/b-hydrolase fold structure | Eur. J. Biochem. 271 2976-2983 2004 FEBS 2004 doi Cloning and expression of a tomato cDNA encoding a methyl jasmonate cleaving esterase Christiane Stuhlfelder Martin J. Mueller and Heribert Warzecha Lehrstuhl fur Pharmazeutische Biologie Julius-von-Sachs-Institut fur Biowissenschaften Universităt Wurzburg Germany Jasmonic acid and its methyl ester are ubiquitous plant signalling compounds necessary for the regulation of growth and development as well as for the response of plants to environmental stress factors. To date it is not clear whether methyl jasmonate itself acts as a signal or if its conversion to jasmonic acid is mandatory prior to the induction of a defense response. We have cloned a cDNA encoding a methyl jasmonate-cleaving enzyme from tomato cell suspension cultures. Sequence analysis revealed significant similarity to plant esterases and to S -hydroxynitrile lyases with an a b-hydrolase fold structure. The coding sequence was heterologously expressed in Escherichia coli and purified in a catalytically active form. Transcript levels as well as enzymatic activity were determined in different tomato tissues. High transcript levels and enzyme activities were found in roots and flowers while the mRNA level and activity were low in stems and leaves. Moreover when tested in methyl jasmonate- and elicitor-treated cell suspension cultures transcript levels were found to decrease indicating that this particular enzyme might be a regulator of jasmonate signalling. Keywords a b-hydrolase cell suspension culture Lyco-persicon esculentum methyl jasmonate esterase Solanaceae. Jasmonic acid JA is a ubiquitous plant compound which plays a crucial role in the response to wounding or pathogen attack as well as in developmental processes such as fruit ripening root growth and fertility 1 . Most of the enzymes involved in JA biosynthesis have been characterized at a biochemical and molecular level and the encoding genes have been cloned.

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