title: Genetic and chemical validation identifies Mycobacterium tuberculosis topoisomerase I as an attractive anti-tubercular target.
abstract: DNA topoisomerases perform the essential function of maintaining DNA topology in prokaryotes. DNA gyrase, an essential enzyme that introduces negative supercoils, is a clinically validated target. However, topoisomerase I (Topo I), an enzyme responsible for DNA relaxation has received less attention as an antibacterial target, probably due to the ambiguity over its essentiality in many organisms. The Mycobacterium tuberculosis genome harbors a single topA gene with no obvious redundancy in its function suggesting an essential role. The topA gene could be inactivated only in the presence of a complementing copy of the gene in M. tuberculosis. Furthermore, down-regulation of topA in a genetically engineered strain of M. tuberculosis resulted in loss of bacterial viability which correlated with a concomitant depletion of intracellular Topo I levels. The topA knockdown strain of M. tuberculosis failed to establish infection in a murine model of TB and was cleared from lungs in two months post infection. Phenotypic screening of a Topo I overexpression strain led to the identification of an inhibitor, thereby providing chemical validation of this target. Thus, our work confirms the attractiveness of Topo I as an anti-mycobacterial target.
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India. Electronic address: mailsuravi01@gmail.com.
authors.forename: Sudha
authors.initials: S
authors.lastname: Ravishankar
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Anisha
authors.initials: A
authors.lastname: Ambady
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Disha
authors.initials: D
authors.lastname: Awasthy
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Naina Vinay
authors.initials: NV
authors.lastname: Mudugal
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Sreenivasaiah
authors.initials: S
authors.lastname: Menasinakai
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Sandesh
authors.initials: S
authors.lastname: Jatheendranath
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Supreeth
authors.initials: S
authors.lastname: Guptha
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Sreevalli
authors.initials: S
authors.lastname: Sharma
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Gayathri
authors.initials: G
authors.lastname: Balakrishnan
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Radha
authors.initials: R
authors.lastname: Nandishaiah
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Vasanthi
authors.initials: V
authors.lastname: Ramachandran
authors.affiliation: AstraZeneca Infection, Innovative Medicines, 35 Gatehouse Drive, Waltham, MA 02451, United States.
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Eyermann
authors.affiliation: AstraZeneca Infection, Innovative Medicines, 35 Gatehouse Drive, Waltham, MA 02451, United States.
authors.forename: Folkert
authors.initials: F
authors.lastname: Reck
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Suresh
authors.initials: S
authors.lastname: Rudrapatna
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Vasan K
authors.initials: VK
authors.lastname: Sambandamurthy
authors.affiliation: AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
authors.forename: Umender K
authors.initials: UK
authors.lastname: Sharma
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism; D055808:Drug Discovery; D015964:Gene Expression Regulation, Bacterial; D055785:Gene Knockdown Techniques; D005838:Genotype; D006801:Humans; D050296:Microbial Viability; D058990:Molecular Targeted Therapy; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D010641:Phenotype; D013997:Time Factors; D059004:Topoisomerase I Inhibitors / Q000494:pharmacology*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D059004:Topoisomerase I Inhibitors; D004264:DNA Topoisomerases, Type I
keywords: Anziaic acid; Essential; Knockdown; Mycobacterium tuberculosis; Phenotypic screening; Topoisomerase I; Vulnerable