Introduction: Pyrazinamide is one of the first line four drugs for treatment of tuberculosis. It was proved that mutations in two nucleotides of 359 and 374 pnc genes are highly associated with resistance to pyrazinamide.
Materials and methods: In this study, mutations in these two codones in 30 clinical isolates of Mycobacterium tuberculosis were detected by means of sequencing. Protein structures encoded by this gene with and without mutation were investigated in resistant and susceptible isolates to pyrazinamide, respectively.
Results: Mutation in the positions 359 and 374 altered some parameters like change in electronic charge, distance change of mutated amino acids to situation of active enzyme and metal connection situation. In these conditions, structure and function of pyrozinamidase enzyme were changed and antibiotic was ineffective and consequently caused resistance to pyrazinamide in M. tuberculosis.
Conclusion: This work was revealed protein changes in resistance to pyrazinamide in clinical isolates of M. tuberculosis.