Menaquinone (vitamin K2) biosynthesis: cloning, nucleotide sequence, and expression of the menC gene from Escherichia...

The benzenoid aromatic compound o-succinylbenzoic acid is formed by dehydration of the prearomatic compound 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylic acid by the enzyme o-succinylbenzoate synthase, encoded by the menC gene. A 1.3-kb PstI-PvuII fragment was found to complement the menC mutation. The complete nucleotide sequence of this fragment revealed a single open reading frame of 954 bp capable of encoding a 35-kDa protein. A consensus sequence for a ribosomal binding site but no promoter consensus sequences were found. However, the first base of the initiating codon of this open reading frame overlaps the upstream menB gene termination codon, suggesting an operon-like organization for these genes. Consistent with this suggestion, the menB promoter can initiate transcription of the menC gene.