title: Insights into Pyrazinamidase and DNA Gyrase Protein Structures in Resistant and Susceptible Clinical Isolates ofMycobacterium tuberculosis.
abstract: BACKGROUND
  Mutations inpncAandgyrAgenes cause pyrazinamide (PZA) and fluroquinolone resistance inMycobacterium tuberculosis(MTB). In the present study, structures of pyrazinamidase (PZase) and DNA gyrase proteins were studied in resistant and susceptible clinical isolates ofMTB.
  
  
  METHODS
  Sixty clinical isolates ofMTBwere used in this study. Polymerase chain reaction (PCR) amplification ofpncAandgyrAgenes was accomplished on purified DNA. Sequence of the fragments was determined by an Applied BiosystemsTM 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 ofpncAandgyrAgenes, 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 resistance-determining 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.
  
  
  CONCLUSIONS
  Structural changes in two important proteins related to drug resistance were proven in clinical isolates ofMTB.
authors.affiliation: Department of Molecular Genetics, Tarbiat Modares University,; Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran.
authors.forename: Azam
authors.initials: A
authors.lastname: Ahmadi
authors.affiliation: Department of Microbiology, Qom Branch, Islamic Azad University, Qom, Iran.
authors.forename: Raziyeh
authors.initials: R
authors.lastname: Nazari
authors.affiliation: Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Arjomandzadegan
authors.affiliation: Department of Microbiology, Qom Branch, Islamic Azad University, Qom, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zolfaghari
authors.affiliation: Department of Microbiology, Qom Branch, Islamic Azad University, Qom, Iran.
authors.forename: Vahideh
authors.initials: V
authors.lastname: Vahidi
authors.affiliation: Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran.
authors.forename: Toktam
authors.initials: T
authors.lastname: Poolad
authors.affiliation: Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran.
authors.forename: Manijeh
authors.initials: M
authors.lastname: Kahbazi
authors.affiliation: Department of Biology, Payame Noor University, I.R. of Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Sadrnia
authors.affiliation: Department of Cellular and Molecular Medicine, Isfahan University, Isfahan, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Tousheh
authors.affiliation: Infectious Diseases Research Center (IDRC), Arak University of Medical Sciences, Arak, Iran.
authors.forename: Pourya
authors.initials: P
authors.lastname: Rafiee
keywords: DNA Gyrase; Mycobacterium tuberculosis; Protein; Pyrazinamidase