In silico analysis of V48A dihydropteroate synthase mutation to dapsone on Mycobacterium leprae from Papua

Background: Leprosy is a disease caused by Mycobacterium leprae. Drug resistance is one of the challenges in leprosy elimination especially in Papua. The presence of mutations in folP1 gene that encode dihydropteroate synthase (DHPS) was considered as the exclusive basis for molecular detection of dapsone resistance in leprosy. The objective of this study was to detect mutations in the folP1 gene of Mycobacterium leprae from Papua, Indonesia and to analyze the effect of these mutations on dapsone using the in-silico method. Methods: Identification of mutations in the folp1 M. leprae gene is carried out through the Basic Local Alignment Search Tool (BLAST) process in the gene bank. The analysis of the effects of mutations using the Have (y)Our Protein Explained (HOPE) server. Bindings pocket prediction is done using the Computed Atlas of Surface Topography of proteins (CASTp). Homology modeling 3D structure of DHPS using the Iterative Threading ASSEmbly Refinement (I-TASSER) server. Docking analysis was performed using AutoDock Vina which is integrated with the Python Prescription (PyRx) application. Results: The sequencing results showed a variation in the folP1 M. leprae gene, namely a change from thymine (T) to cytosine (C) in nucleotide 143. The mutated residue (V48A) is in a domain that is essential for the activity of the protein and in contact with residues in another domain. It is possible that this interaction is important for the correct function of the protein. V48A mutants did not significantly affect the stability of DHPS M. leprae. Conclusion: Based on molecular docking analysis, this mutation does not affect binding affinity dapsone against M. leprae dihydropteroate synthase. These results indicate that the V48A mutant is likely to remain susceptible to dapsone. Thus, it is necessary to do an in vivo test to confirm the effect of the V48A mutation. (Health Science Journal of Indonesia 2020;11(2):70-6)