Bacillus subtilis fadB (ysiB) gene encodes an enoyl-CoA hydratase

Fatty acids are essential components of membranes and are an important source of metabolic energy. In bacteria, the beta-oxidation pathway is well known in Escherichia coli. Bacillus subtilis possesses a considerable number of genes, organized in five operons, that are most likely involved in the beta-oxidation of fatty acids. Among these genes, only one product, FadR(Bs) (YsiA), has been recently characterized as a transcriptional regulatory protein which negatively regulates the expression of beta-oxidation genes including those belonging to the lcfA operon, including fadR (Bs) (ysiA). The probable involvement of the FadR(Bs) (YsiA) regulon members in beta-oxidation is inferred from data based on BLASTP similarity of their gene products. In this work, we report the cloning and the expression of B. subtilis fadB (Bs)(ysiB), belonging to the lcfA operon, and the functional characterization of its product as an enoyl-CoA hydratase, demonstrating the actual involvement of these genes in fatty acid beta-oxidation.