The benzoate degradation pathway involves the conversion of benzoate into intermediates that can enter central metabolic pathways such as the TCA cycle. This process is mediated by the catBCIJFD operon, which encodes enzymes responsible for the ortho-cleavage pathway of catechol, a key intermediate in benzoate catabolism. The catBCIJFD operon is made up of 6 genes (catB, catC, catI, catJ, catF and catD). It is regulated by two genes outside of the operon - CatM and an adjacent gene, benM, which encode LysR-type transcriptional regulators that can act both as activators and repressors of the catBCIJFD operon. cis,cis-muconate (CCM), produced from catechol ring cleavage, interacts with the LysR-type transcriptional regulator, to activate expression catBCIJFD operon. catB encodes Muconate cycloisomerase 1, an enzyme that converts cis,cis-muconate (a product of catechol cleavage) into muconolactone, catC encodes Muconolactone Delta-isomerase, which converts muconolactone into beta-ketoadipate enol-lactone, catD encodes β-ketoadipate enol-lactone hydrolase II also referred to as 3-oxoadipate enol-lactonase 2, which catalyzes the formation of beta-ketoadipate from beta-ketoadipate enol-lactone, catI and catJ encode 3-oxoadipate CoA-transferase subunit A and 3-oxoadipate CoA-transferase subunit B, which catalyze conversion of beta-ketoadipate to beta-ketoadipyl-CoA and lastly, catF encodes Beta-ketoadipyl-CoA thiolase, which converts beta-ketoadipyl-CoA into Succinyl-CoA and Acetyl-CoA which can then enter the TCA cycle.

Benzoate degradation (catBCIJFD Operon activation) References