A second cinnamoyl ester hydrolase (CEH) encoding gene () has been characterized from the ruminal bacterium E14. CinB is more similar to CinA (previously named Cinl) (28% amino acid identity), the first CEH described from E14, than either of the enzymes are to any other member of the family of hydrolases to which they belong. Upstream of and in the opposite orientation, is a gene () encoding a protein with substantial similarity to members of the MarR family of negative regulators of bacterial gene expression. By alignment of these sequences, a possible helix-turn-helix DNA-binding domain has been identified. CinR was expressed at a high level in using the promoter. In CinR repressed the expression of CinB, but had no effect on the expression of CinA. In gel mobility-shift assays, CinR bound specifically to the intergenic region. Two identical 16 nucleotide inverted repeats adjacent to the putative P and P promoters are likely binding sites for CinR. The addition of FAXX (-[5--()-α--arabinofuranosyl]-(1,3)--ß--xylopyranosyl-(1,4)--xylopyranose) and Fara [5--(-feruloyl)-arabinofuranose], but not xylobiose, ferulic acid and a number of other soluble components of hemicellulose, inhibited the binding of CinR to DNA.


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