Positively regulates the expression of catA, catBCIJFD and benPK in response to cis,cis-muconate. It binds to the catB-catM intercistronic region, to a specific sequence upstream of catA and to the benPK promoter region. Can also repress pca genes. Homotetramer in solution. Negatively autoregulated. Belongs to the LysR transcriptional regulatory family. Was originally (PubMed:2793826) reported to be a transcriptional repressor of cat genes. However, further investigations have shown it to be a transcriptional activator.