Comparative study of enzymatic activities of new KatG mutants from low- and high-level isoniazid-resistant clinical isolates of Mycobacterium tuberculosis. (September 2016)

• Record Type: Journal Article
• Authors: Brossier, Florence; Boudinet, Marlène; Jarlier, Vincent; Petrella, Stéphanie; Sougakoff, Wladimir
• Is Part Of: Tuberculosis. Volume 100(2016)
• Page Start: 15
• Page End: 24
• Publication Date: 2016-09
• Subjects: Tuberculosis -- Resistance -- Isoniazid -- Catalase-peroxidase -- KatG -- Enzymatic activities; G/Gox glucose/glucose oxidase -- IN isonicotinoyl acyl radical -- INH isoniazid -- IN-NAD isonicotinoyl-NAD -- NBT nitroblue tetrazolium -- R resistance -- Rz optical purity ratio of Reinheitszahl -- TB tuberculosis -- tBHP tert-butyl hydroperoxide -- WT wild-type; 616.995
• DOI: 10.1016/j.tube.2016.06.002
• Languages: English
• ISSNs: 1472-9792

Abstract

Summary: Resistance to isoniazid (INH-R) in Mycobacterium tuberculosis is mainly due to mutations at position 315 (S315T) of the catalase-peroxidase KatG. We identified 16 mutations (including 13 biochemically uncharacterized mutations) in KatG from INH-R clinical isolates of M. tuberculosis showing mutations other than S315T. The KatG enzymatic activities (catalase, peroxidase, free radical production and isonicotinoyl-NAD formation) of wild-type KatG and the 16 mutants were determined and correlated to their spatial location in a KatG model structure. Of all mutations studied, H270R, which conferred a high level of INH-R and results in the disruption of a coordination bond with the heme, caused complete loss of all enzymatic KatG activities. The mutants generally associated with a very high level of INH-R were all characterized by a drastic reduction in catalase activity and a marked decrease in INH activation activities. One mutant, A162E, displayed a behavior similar to S315T, i.e. a moderate decrease in catalase activity and a drastic decrease in the formation of the radical form of INH. Finally, the mutants associated with a low level of INH-R showed a moderate reduction in the four catalytic activities, likely stemming from an overall alteration of the folding and/or stability of the KatG protein.