The Interaction of Isoniazid on 3D Structure Variation of NAT2 Gene and Its Effect on Drug Blood Levels

Drug-Resistant Tuberculosis (DR-TB) and Anti-TB Drug-Induced Liver
\nInjury (AT-DILI) are frequently linked to polymorphisms in drug-
\nmetabolizing enzymes (DMEs). Among these, arylamine N-
\nacetyltransferase 2 (NAT2) plays a pivotal role in metabolizing isoniazid
\n(INH). This study investigates the structural and functional effects of
\nNAT2 polymorphisms on INH interactions. Using the 3D structure of
\nwild-type NAT2 (PDB ID: 2PFR) as a template, we employed Chimera,
\nAutoDock, GROMACS, and VMD software for molecular docking and
\ndynamic simulations. Five common coding SNPs in NAT2—G191A,
\nT341C, G590A, A803G, and G857A—were combined to produce 15
\nmutant NAT2 variants. The DNA sequences of 12 TB patients from a
\npublic health center in Surabaya, Indonesia, were used to correlate
\nacetylator phenotypes with the INH blood levels. The molecular docking
\nanalysis revealed that the binding affinity of INH to wild-type NAT2 was
\n-5.7 kcal/mol, which is similar to most mutants. Minor variations were
\nobserved among the mutants, with affinities ranging from -5.6 to -5.7
\nkcal/mol. Mutants 2, 6, 8, 9, 10, 12, 14, and 15 (rapid acetylators) showed
\na decrease in interaction with residue G124, while new binding with
\nresidue L288 was identified in mutants 1, 3, 4, 5, and 7 (slow acetylators).
\nThese discrepancies in interactions point to a structural foundation for
\ndisparities in acetylation rates and enzyme activity. Correlations between
\nthe INH–NAT2 interaction patterns and patient acetylator phenotypes
\nrevealed distinct impacts on INH blood levels, highlighting potential
\nimplications for DR-TB treatment outcomes and AT-DILI risk