Catabolite Repression of the Bacillus subtilis FadR Regulon, Which Is Involved in Fatty Acid Catabolism

TheBacillus subtilis fadR regulon involved in fatty acid degradation comprises five operons,lcfA-fadR-fadB-etfB-etfA ,lcfB ,fadN-fadA-fadE ,fadH-fadG , andfadF-acdA-rpoE . Since thelcfA-fadRB-etfBA ,lcfB , andfadNAE operons, whose gene products directly participate in the β-oxidation cycle, had been found to be probably catabolite repressed upon genome-wide transcript analysis, we performed Northern blotting, which indicated that they are clearly under CcpA-dependent catabolite repression. So, we searched for catabolite-responsive elements (cre 's) to which the complex of CcpA and P-Ser-HPr binds to exert catabolite repression by means of a web-basedcis -element search in theB. subtilis genome using knowncre sequences, which revealed the respective candidatecre sequences in thelcfA ,lcfB , andfadN genes. DNA footprinting indicated that the complex actually interacted with thesecre 'sin vitro . Deletion analysis of eachcre using thelacZ fusions with the respective promoter regions of the three operons with and without it, indicated that thesecre 's are involved in the CcpA-dependent catabolite repression of the operonsin vivo .