METABOLISM OF FERULIC ACID TO VANILLIN - A BACTERIAL GENE OF THE ENOYL-SCOA HYDRATASE ISOMERASE SUPERFAMILY ENCODES AN ENZYME FOR THE HYDRATION AND CLEAVAGE OF A HYDROXYCINNAMIC ACID SCOA THIOESTER/

A gene encoding a novel enoyl-SCoA hydratase/lyase enzyme for the hydr ation and nonoxidative cleavage of feruloyl-SCoA to vanillin and acety l-SCoA was isolated and characterized from a strain of Pseudomonas flu orescens. Feruloyl-SCoA is the CoASH thioester of ferulic acid (4-hydr oxy-3-methoxy-trans-cinnamic acid), an abundant constituent of plant c ell walls and a degradation product of lignin. The gene was isolated b y a combination of mutant complementation and biochemical approaches, and its function was demonstrated by heterologous expression in Escher ichia coli under the control of a T7 RNA polymerase promoter. The gene product is a member of the enoyl-SCoA hydratase/isomerase superfamily .