National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran TANAFFOS (Respiration) 1735-0344 15 3 2016 10 01 nsights into Pyrazinamidase and DNA Gyrase Protein Structures in Resistant and Susceptible Clinical Isolates of Mycobacterium tuberculosis 147 153 240218 EN Azam Ahmadi Department of Molecular Genetics, Tarbiat Modares University, Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran, Raziyeh Nazari Department of Microbiology, Qom Branch, Islamic Azad University, Qom, Iran, Mohammad Arjomandzadegan Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran, Mohammad Reza Zolfaghari Department of Microbiology, Qom Branch, Islamic Azad University, Qom, Iran, Vahideh Vahidi Department of Microbiology, Qom Branch, Islamic Azad University, Qom, Iran, Toktam Poolad Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran, Manijeh Kahbazi Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran, Maryam Sadrnia Department of Biology, Payame Noor University, I.R. of Iran, Mojtaba Tousheh Department of Cellular and Molecular Medicine, Isfahan University, Isfahan, Iran Pourya Rafiee Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran, Journal Article 2020 12 25 Background: Mutations in pncA and gyrA genes cause pyrazinamide (PZA) and fluroquinolone resistance in Mycobacterium tuberculosis (MTB). In the present study, structures of pyrazinamidase (PZase) and DNA gyrase proteins were studied in resistant and susceptible clinical isolates of MTB. Materials and Methods: Sixty clinical isolates of MTB were used in this study. Polymerase chain reaction (PCR) amplification of pncA and gyrA genes was accomplished on purified DNA. Sequence of the fragments was determined by an Applied Biosystems TM apparatus. Bioinformatic analysis was performed by online software and three-dimensional (3D) structures of proteins was predicted using Molegro Virtual Docker (MVD) Modeler software. Results: Amplified 744 and 194 bp fragments of pncA and gyrA genes, respectively were yielded suitable sequence results. Predicted 3D structures of proteins showed some differences between wild-type and mutant structures. Mutation in amino acid No.31 (T92C) caused an increase in distance from metal ion position to enzyme active site, but it was considered as a polymorphism. Docking results by MVD revealed a relationship in quinolone resistancedetermining regions (QRDR) amino acids in interaction with antibiotic. T92C mutation in PZase from non-polar aliphatic amino acid Ile (ATC) to polar aliphatic amino acid threonine (ACC) was a polymorphism. Conclusion: Structural changes in two important proteins related to drug resistance were proven in clinical isolates of MTB. https://www.tanaffosjournal.ir/article_240218_e35e4d49adb51ac41ed398a6f969287f.pdf