Mycobacterial catalase-peroxidase (KatG)

Mycobacterial catalase-peroxidase (KatG) is a multifunctional, heme-dependent enzyme found in *Mycobacterium tuberculosis* and related species. It is primarily responsible for activating the first-line antituberculosis prodrug isoniazid (INH). KatG catalyzes both the decomposition of hydrogen peroxide (catalatic activity) and the oxidation of peroxidatic substrates (peroxidatic activity)[1][2][3][4][5]. Structurally, KatG is notable for its homodimer assembly and unique MYW cofactor, which mediates its robust catalase activity—a feature absent in other members of its superfamily[3][5]. Point mutations or deletions in the KatG gene significantly reduce or abolish enzymatic activity, resulting in resistance to isoniazid and posing a critical challenge to tuberculosis therapy[1][2][4]. KatG also protects mycobacteria from host-derived reactive oxygen and nitrogen species, has auxiliary roles in DNA repair, and exemplifies the intricate molecular adaptation of pathogenic mycobacteria[4][5]. Detection of KatG or its mutations serves as a biomarker for clinical management of tuberculosis, and its loss of function is a key mechanism behind multidrug resistance in clinical isolates[1][2][4].

Other names

KatGMycobacterium tuberculosis catalase-peroxidaseHydroperoxidase ICatalase-peroxidase enzyme

Activation of isoniazid via catalase-peroxidase enzymatic reaction Mutation-mediated loss or reduction of activity leads to drug resistance