Coordinated regulation of 4-coumarate:CoA ligase and phenylalanine ammonia-lyase mRNAs in cultured plant cells.

4-Coumarate:CoA ligase (EC 6.2.1.12) from cell suspension cultures of parsley (Petroselinum hortense) was extensively purified. The enzyme behaved as a monomer with a molecular weight of approximately 60,000. A rabbit antiserum to the purified enzyme was obtained and used to determine the rates of 4-coumarate:CoA ligase synthesis under various conditions of induction, such as short term or continuous irradiation and treatment of the cells with an "elicitor" preparation from a fungal pathogen. In all cases, the time course of changes in the rate of synthesis, measured both in vivo and in vitro, was very similar for 4-coumarate:CoA ligase and a closely related enzyme, phenylalanine ammonia-lyase (EC 4.3.1.5). The results suggest that the mRNA activities encoding the two enzymes are regulated in a coordinated manner.