The benzoate catabolism pathway is a key metabolic pathway that allows bacteria to utilize benzoate as a carbon source and involves the conversion of benzoate into intermediates that can enter the citric acid cycle. The benABCD operon responsible contains 4 genes benA, benB, benC, benD. The operon is activated by the benM gene which encodes for a transcriptional regulator and is outside of this operon. This operon is activated in the presence of benzoate, which binds to the transcriptional regulator, enhancing its ability to bind the promoter and facilitate RNA polymerase recruitment, thus initiating transcription. benA encodes benzoate 1,2-dioxygenase alpha subunit, which is part of the enzyme complex that catalyzes the initial dioxygenation of benzoate to form catechol which enters the catechil ortho-cleavage pathway and eventually feeds the TCA cycle. benB encodes benzoate 1,2-dioxygenase beta subunit, which works in conjunction with BenA to catalyze the same reaction. benC encodes a reductase that reduces NAD to NADH which is required in the BenAB complex for the dioxygenation reaction to form dihydrodiol. benD encodes cis-1,2-dihydroxycyclohexa-3,5-diene-1-carboxylate dehydrogenase, which converts the intermediate product (dihydrodiol) into catechol. Additionally, the operon is influenced by benK and benP which are also outside of the operon and encode for membrane transporters involved in the uptake of benzoate into the cell.

Benzoate Catabolism Pathway (benABCD Operon Activation) References