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Plant Physiology 96:327-330 (1991) © 1991 American Society of Plant Biologists Kinetic Characterization of Caffeoyl-Coenzyme A-Specific 3-O-Methyltransferase from Elicited Parsley Cell Suspensions 1Institut für Biologie II, Lehrstuhl für Biochemie der Pflanzen, Universität Freiburg, D-7800 Freiburg, Federal Republic of Germany
The activity of caffeoyl-coenzyme A (CoA) 3-O-methyltransferase, an enzyme widely distributed in plants and involved in cell wall reinforcement in a disease resistance response, appears to be subject to a complex type of regulation in vivo. In cultured parsley (Petroselinum crispum) cells treated with an elicitor from Phytophthora megasperma f.sp. glycinea, the enzyme activity is rapidly induced by a transient increase in the rate of de novo transcription. Parsley caffeoyl-CoA-specific methyltransferase differs in several aspects from other plant O-methyltransferases but shows limited homology to bacterial adenine-specific DNA methyltransferases. Kinetic analysis revealed an Ordered Bi Bi mechanism for catalysis, with caffeoyl-CoA bound prior to S-adenosyl-L-methionine and feruloyl-CoA released last from the enzyme. The small inhibitory constant determined in vitro for feruloyl-CoA suggests that, in vivo, the enzyme activity is also under tight control by the steady-state product concentration in addition to the rate of transcription that becomes affected upon elicitor challenge.
1 The work described in this report was supported by Deutsche Forschungsgemeinschaft (SFB 206) and Fonds der Chemischen Industrie. This article has been cited by other articles:
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