title: The Inosine Monophosphate Dehydrogenase, GuaB2, Is a Vulnerable New Bactericidal Drug Target for Tuberculosis.
abstract: VCC234718, a molecule with growth inhibitory activity against Mycobacterium tuberculosis (Mtb), was identified by phenotypic screening of a 15344-compound library. Sequencing of a VCC234718-resistant mutant identified a Y487C substitution in the inosine monophosphate dehydrogenase, GuaB2, which was subsequently validated to be the primary molecular target of VCC234718 in Mtb. VCC234718 inhibits Mtb GuaB2 with a Kiof 100 nM and is uncompetitive with respect to IMP and NAD+. This compound binds at the NAD+site, after IMP has bound, and makes direct interactions with IMP; therefore, the inhibitor is by definition uncompetitive. VCC234718 forms strong pi interactions with the Y487 residue side chain from the adjacent protomer in the tetramer, explaining the resistance-conferring mutation. In addition to sensitizing Mtb to VCC234718, depletion of GuaB2 was bactericidal in Mtb in vitro and in macrophages. When supplied at a high concentration (≥125 μM), guanine alleviated the toxicity of VCC234718 treatment or GuaB2 depletion via purine salvage. However, transcriptional silencing of guaB2 prevented Mtb from establishing an infection in mice, confirming that Mtb has limited access to guanine in this animal model. Together, these data provide compelling validation of GuaB2 as a new tuberculosis drug target.
authors.affiliation: MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine & Department of Pathology, University of Cape Town , Anzio Road, Observatory 7925, South Africa.
authors.forename: Vinayak
authors.initials: V
authors.lastname: Singh
authors.affiliation: Dipartimento di Scienze del Farmaco, University of Piemonte Orientale , Via Bovio 6, 28100 Novara, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Donini
authors.affiliation: Department of Biochemistry, University of Cambridge , 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom.
authors.forename: Angela
authors.initials: A
authors.lastname: Pacitto
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sala
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Ruben C
authors.initials: RC
authors.lastname: Hartkoorn
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Dhar
authors.affiliation: Vichem Chemie , Herman Ottó út 15, Budapest, 1022 Hungary.
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Keri
authors.affiliation: Department of Biochemistry, University of Cambridge , 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom.
authors.forename: David B
authors.initials: DB
authors.lastname: Ascher
authors.affiliation: Sanofi-Aventis Research & Development , Infectious Diseases Unit, Biology Group, Campus Mérieux, 1541 avenue Marcel Mérieux, 69280 Marcy L'Etoile, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Mondésert
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Anthony
authors.initials: A
authors.lastname: Vocat
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Andréanne
authors.initials: A
authors.lastname: Lupien
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Sommer
authors.affiliation: Sanofi-Aventis Research & Development , Infectious Diseases Unit, Biology Group, Campus Mérieux, 1541 avenue Marcel Mérieux, 69280 Marcy L'Etoile, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Vermet
authors.affiliation: Sanofi-Aventis Research & Development , Infectious Diseases Unit, Biology Group, Campus Mérieux, 1541 avenue Marcel Mérieux, 69280 Marcy L'Etoile, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Lagrange
authors.affiliation: Alere (San Diego) , Summer Ridge Road, San Diego, California 92121, United States.
authors.forename: Joe
authors.initials: J
authors.lastname: Buechler
authors.affiliation: MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine & Department of Pathology, University of Cape Town , Anzio Road, Observatory 7925, South Africa.
authors.forename: Digby F
authors.initials: DF
authors.lastname: Warner
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: John D
authors.initials: JD
authors.lastname: McKinney
authors.affiliation: Vichem Chemie , Herman Ottó út 15, Budapest, 1022 Hungary.
authors.forename: Janos
authors.initials: J
authors.lastname: Pato
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, Global Health Institute , Station 19, 1015 Lausanne, Switzerland.
authors.forename: Stewart T
authors.initials: ST
authors.lastname: Cole
authors.affiliation: Department of Biochemistry, University of Cambridge , 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom.
authors.forename: Tom L
authors.initials: TL
authors.lastname: Blundell
authors.affiliation: Dipartimento di Scienze del Farmaco, University of Piemonte Orientale , Via Bovio 6, 28100 Novara, Italy.
authors.forename: Menico
authors.initials: M
authors.lastname: Rizzi
authors.affiliation: MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine & Department of Pathology, University of Cape Town , Anzio Road, Observatory 7925, South Africa.
authors.forename: Valerie
authors.initials: V
authors.lastname: Mizrahi
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D055808:Drug Discovery; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D016680:Genome, Bacterial; D007168:IMP Dehydrogenase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D009161:Mycobacterium / Q000187:drug effects*; D013450:Sulfones / Q000494:pharmacology*; D014376:Tuberculosis / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D013450:Sulfones; C000626192:VCC234718; D007168:IMP Dehydrogenase
keywords: IMPDH; Mycobacterium tuberculosis; drug target; purine nucleotide; purine salvage