Molecular docking analysis of the T450A mutation of the gene rpob Mycobacterium leprae from leprosy patients in Papua, West Papua and North Maluku, Indonesia

Leprosy persists to be a health problem in Indonesia, especially in the provinces of North Maluku, West Papua and Papua. Early diagnosis and complete treatment with multidrug therapy (MDT) remain the key strategy for reducing the disease burden. One of the major components of MDT is rifampicin which in certain cases in several countries, M. leprae resistance to this drug issue has been reported albeit only a few. This research aimed to detect and analyze polymorphism in M. leprae rpoB gene that was isolated from leprosy patients in three provinces: North Maluku Province, West Papua Province and Papua Province, Indonesia. The identification of mutations in the M. leprae rpoB gene was carried out by aligning the results of DNA sequencing with the reference strain. The 3D structure of rpoB was derived using the Swiss Model. The T450A, S456L, and H451Y variants of RNA Polymerase B subunits were constructed using FoldX based on the wild-type structure. The structures were repaired, and protein stability was evaluated using foldX under the Yasara viewer. The QC of the rpoB M. leprae homology models was conducted with Ramachandran Plot modeling using PROCHECK. The difference in binding affinity between native protein and T450A, S456L, and H45I variants were analyzed using molecular docking. rpoB gene of M. leprae contains a mutation found in nucleotide of 1348 bp. The mutation triggered the conversion of the amino acid Threonine to Alanine in the amino acid to 450 rpoB subunit B. The structure of 3D RNA Polymerase Subunit B was constructed using rpoB Mycobacterium tuberculosis with PDB code 5UH5 as template. According to Ramachandran Plot, the percentage of residues in the most favored regions are 91.9%, and there was no significant number of residues in the disallowed regions. The results of molecular docking showed that the T450A variant had the same binding affinity with the native protein which was -8.9 kcal. Binding affinity on the S456L and H451Y variants increased by -7.3 kcal and -8.2 kcal, respectively. According to Molecular Docking analysis, T450A variant did not affect the energy binding between RNA polymerase and rifampicin.