Title | Essential but Not Vulnerable: Indazole Sulfonamides Targeting Inosine Monophosphate Dehydrogenase as Potential Leads against Mycobacterium tuberculosis. |
Publication Type | Journal Article |
Year of Publication | 2017 |
Authors | Park Y, Pacitto A, Bayliss T, Cleghorn LAT, Wang Z, Hartman T, Arora K, Ioerger TR, Sacchettini J, Rizzi M, Donini S, Blundell TL, Ascher DB, Rhee K, Breda A, Zhou N, Dartois V, Jonnala SReddy, Via LE, Mizrahi V, Epemolu O, Stojanovski L, Simeons F, Osuna-Cabello M, Ellis L, MacKenzie CJ, Smith ARC, Davis SH, Murugesan D, Buchanan KI, Turner PA, Huggett M, Zuccotto F, Rebollo-Lopez MJose, Lafuente-Monasterio MJose, Sanz O, Diaz GSantos, Lelièvre J, Ballell L, Selenski C, Axtman M, Ghidelli-Disse S, Pflaumer H, Bösche M, Drewes G, Freiberg GM, Kurnick MD, Srikumaran M, Kempf DJ, Green SR, Ray PC, Read K, Wyatt P, Barry CE, Boshoff HI |
Journal | ACS Infect Dis |
Volume | 3 |
Issue | 1 |
Pagination | 18-33 |
Date Published | 2017 01 13 |
ISSN | 2373-8227 |
Keywords | Animals, Antitubercular Agents, Drug Design, Drug Discovery, Drug Resistance, Bacterial, Gene Expression Regulation, Bacterial, Gene Expression Regulation, Enzymologic, Humans, IMP Dehydrogenase, Mice, Mice, Inbred C57BL, Molecular Structure, Mutation, Mycobacterium tuberculosis, Protein Conformation, Rabbits, Structure-Activity Relationship, Sulfonamides, Tuberculosis |
Abstract | A potent, noncytotoxic indazole sulfonamide was identified by high-throughput screening of >100,000 synthetic compounds for activity against Mycobacterium tuberculosis (Mtb). This noncytotoxic compound did not directly inhibit cell wall biogenesis but triggered a slow lysis of Mtb cells as measured by release of intracellular green fluorescent protein (GFP). Isolation of resistant mutants followed by whole-genome sequencing showed an unusual gene amplification of a 40 gene region spanning from Rv3371 to Rv3411c and in one case a potential promoter mutation upstream of guaB2 (Rv3411c) encoding inosine monophosphate dehydrogenase (IMPDH). Subsequent biochemical validation confirmed direct inhibition of IMPDH by an uncompetitive mode of inhibition, and growth inhibition could be rescued by supplementation with guanine, a bypass mechanism for the IMPDH pathway. Beads containing immobilized indazole sulfonamides specifically interacted with IMPDH in cell lysates. X-ray crystallography of the IMPDH-IMP-inhibitor complex revealed that the primary interactions of these compounds with IMPDH were direct pi-pi interactions with the IMP substrate. Advanced lead compounds in this series with acceptable pharmacokinetic properties failed to show efficacy in acute or chronic murine models of tuberculosis (TB). Time-kill experiments in vitro suggest that sustained exposure to drug concentrations above the minimum inhibitory concentration (MIC) for 24 h were required for a cidal effect, levels that have been difficult to achieve in vivo. Direct measurement of guanine levels in resected lung tissue from tuberculosis-infected animals and patients revealed 0.5-2 mM concentrations in caseum and normal lung tissue. The high lesional levels of guanine and the slow lytic, growth-rate-dependent effect of IMPDH inhibition pose challenges to developing drugs against this target for use in treating TB. |
DOI | 10.1021/acsinfecdis.6b00103 |
Alternate Journal | ACS Infect Dis |
PubMed ID | 27704782 |
PubMed Central ID | PMC5972394 |
Grant List | / / Wellcome Trust / United Kingdom Z99 AI999999 / / Intramural NIH HHS / United States |