CLONING OF A GENE ENCODING CINNAMOYL ESTER HYDROLASE FROM THE RUMINALBACTERIUM BUTYRIVIBRIO-FIBRISOLVENS E14 BY A NOVEL METHOD

A gene (cinI) encoding a cinnamoyl ester hydrolase (CEH) has been isol ated from the ruminal bacterium, Butyrivibrio fibrisolvens E14, using a model substrate, MUTMAC [4-methylumbelliferoyl (p-trimethylammonium cinnamate chloride)]. CinI has significant amino-acid similarities wit h members of a large and diverse family of hydrolases with a serine/as partic acid/histidine catalytic triad. Our analyses identified two pre viously unclassified amino acid sequences, the amino-terminal domain o f unknown function in XynZ from Clostridium thermocellum and XynC, an acetylxylan esterase from Caldicellulosiruptor saccharolyticus, as mem bers of the same family of hydrolases. A previously described esterase with CEH activity, XylD from Pseudomonas fluorescens ssp. cellulosa, is not similar to CinI. CinI was expressed at high levels in the perip lasmic fraction of E. coli TOPP2 and released ferulic acid from Fara [ 5-O-(trans-feruloyl)-arabinofuranose] prepared from wheat bran.