title: Double Mutants in DNA Gyrase Lead to Ofloxacin Resistance in Mycobacterium tuberculosis.
abstract: Fluoroquinolones are among the most important classes of highly effective antibacterial drugs, exhibiting wide range of activity to cure infectious diseases. Ofloxacin is second generation fluoroquinolone approved by FDA for the treatment of tuberculosis by selectively inhibiting DNA gyrase. However, the emergence of drug resistance owing to mutations in DNA gyrase poses intimidating challenge for the effective therapy of this drug. The double mutants GyrAA90VGyrBD500Nand GyrAA90VGyrBT539Nare reported to be implicated in conferring higher levels of OFX resistance. The present study was designed to unravel the molecular principles behind development of resistance by the bug against fluoroquinolones. Our results highlighted that polar interactions play critical role in the development of drug resistance and highlight the significant correlation between the free energy calculations predicted by MM-PBSA and stability of the ligand-bound complexes. Modifications at the OFX binding pocket due to amino acid substitution leads to fewer hydrogen bonds in mutants DNA gyrase-OFX complex, which determined the low susceptibility of the ligand in inhibiting the mutant protein. This study provides a structural rationale to the mutation-based resistance to ofloxacin and will pave way for development potent fluoroquinolone-based resistant-defiant drugs. J. Cell. Biochem. 118: 2950-2957, 2017. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Department of Biotechnology, Panjab University, Chandigarh, 160014, India.
authors.forename: Bharati
authors.initials: B
authors.lastname: Pandey
authors.affiliation: Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India.
authors.forename: Sonam
authors.initials: S
authors.lastname: Grover
authors.affiliation: Department of Microbiology, University of Szeged, Hungary, H-6720 Szeged, Dugonics Square 13, Hungary.
authors.forename: Chetna
authors.initials: C
authors.lastname: Tyagi
authors.affiliation: Department of Bioscience and Biotechnology, Banasthali University, Tonk, 304022, Rajasthan, India.
authors.forename: Sukriti
authors.initials: S
authors.lastname: Goyal
authors.affiliation: Department of Bioscience and Biotechnology, Banasthali University, Tonk, 304022, Rajasthan, India.
authors.forename: Salma
authors.initials: S
authors.lastname: Jamal
authors.affiliation: Department of Biotechnology, TERI University, New Delhi, 110070, India.
authors.forename: Aditi
authors.initials: A
authors.lastname: Singh
authors.affiliation: Department of Biotechnology, Panjab University, Chandigarh, 160014, India.
authors.forename: Jagdeep
authors.initials: J
authors.lastname: Kaur
authors.affiliation: School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
authors.forename: Abhinav
authors.identifier: 0000-0002-3296-7860
authors.initials: A
authors.lastname: Grover
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D027081:DNA Gyrase / Q000235:genetics / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D020125:Mutation, Missense; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000235:genetics; D015242:Ofloxacin
chemical_list: D001426:Bacterial Proteins; D015242:Ofloxacin; D027081:DNA Gyrase
keywords: DNA GYRASE; DOUBLE MUTANT; FLUOROQUINOLONES; MOLECULAR DYNAMICS; MYCOBACTERIUM TUBERCULOSIS