title: Conditional silencing of topoisomerase I gene of Mycobacterium tuberculosis validates its essentiality for cell survival.
abstract: Topoisomerases are an important class of enzymes for regulating the DNA transaction processes. Mycobacterium tuberculosis (Mtb) is one of the most formidable pathogens also posing serious challenges for therapeutic interventions. The organism contains only one type IA topoisomerase (Rv3646c), offering an opportunity to test its potential as a candidate drug target. To validate the essentiality of M. tuberculosis topoisomerase I (TopoI(Mt) ) for bacterial growth and survival, we have generated a conditionally regulated strain of topoI in Mtb. The conditional knockdown mutant exhibited delayed growth on agar plate. In liquid culture, the growth was drastically impaired when TopoI expression was suppressed. Additionally, novobiocin and isoniazid showed enhanced inhibitory potential against the conditional mutant. Analysis of the nucleoid revealed its altered architecture upon TopoI depletion. These studies establish the essentiality of TopoI for the M. tuberculosis growth and open up new avenues for targeting the enzyme.
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
authors.forename: Wareed
authors.initials: W
authors.lastname: Ahmed
authors.forename: Shruti
authors.initials: S
authors.lastname: Menon
authors.forename: Adwait Anand
authors.initials: AA
authors.lastname: Godbole
authors.forename: Pullela V D N B
authors.initials: PV
authors.lastname: Karthik
authors.forename: Valakunja
authors.initials: V
authors.lastname: Nagaraja
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D055785:Gene Knockdown Techniques; D020043:Genes, Essential; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D009675:Novobiocin / Q000494:pharmacology; D010078:Oxazines / Q000494:pharmacology; D013754:Tetracyclines / Q000378:metabolism; D014376:Tuberculosis / Q000382:microbiology*; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C513697:CRP protein, Mycobacterium tuberculosis; D010078:Oxazines; D013754:Tetracyclines; D014966:Xanthenes; D009675:Novobiocin; C005843:resazurin; C016229:4-epianhydrotetracycline; D004264:DNA Topoisomerases, Type I; D007538:Isoniazid
keywords: Mycobacterium tuberculosis; cell growth; conditional silencing; essential genes; topoisomerase I