Disease relevance of catB

• Mutations in catB, the gene encoding muconate cycloisomerase, activate transcription of the distal ben genes and contribute to a complex regulatory circuit in Acinetobacter sp. strain ADP1 [1].

High impact information on catB

• In relation to CatM, CatM(V158M) increased cis,cis-muconate-dependent transcription of benA but decreased that of catB [2].
• Consistent with this model, muconate cylcoisomerase specific activities in cell extracts of benzoate-grown catB mutants were low relative to that of the wild type [1].
• All of the catB mutations increased cis,cis-muconate-activated ben gene expression in strains lacking BenM [1].
• In a catM-disrupted strain, BenM was able to induce higher levels of catA expression than catB expression [3].
• Interestingly, further analysis of the two DNA fragments revealed the locations of the catB and catC genes as well [4].

Biological context of catB

• A third open reading frame, beginning 123 bp upstream from catB and transcribed divergently from this gene, was designated catM [5].
• In support of this hypothesis, in vivo methylation protection assays showed that CatM protects two guanines in a dyad 65 nucleotides upstream of the catB transcriptional start site, in a location and pattern typical of LysR-type transcriptional activators [6].
• Removal of the DNA between the SalI sites created a deletion removing the terminal 35 base pairs of the catB gene, the 300-base-pair catC gene, and about 1.1 kb of the 1.2-kb catE gene [7].
• Investigating this anomaly, we found that insertional inactivation of catM did not cause the phenotype expected for the disruption of a repressor-encoding gene: in an interposon-generated catM mutant, no cat genes were expressed constitutively, but rather catA and catB were still inducible by muconate [6].

Associations of catB with chemical compounds

• Two structural genes needed for catechol degradation, catA and catB, encode the respective enzymes catechol 1,2-dioxygenase (EC 1.13.11.1) and muconate cycloisomerase (EC 5.5.1.1) [5].

References