Selective small molecule inhibitor of the Mycobacterium tuberculosis fumarate hydratase reveals an allosteric regulatory site.
Enzymes in essential metabolic pathways are attractive targets for the treatment of bacterial diseases, but in many cases, the presence of homologous human enzymes makes them impractical candidates for drug development. Fumarate hydratase, an essential enzyme in the tricarboxylic acid (TCA) cycle, has been identified as one such potential therapeutic target in tuberculosis. We report the discovery of the first small molecule inhibitor, to our knowledge, of the Mycobacterium tuberculosis fumarate hydratase. A crystal structure at 2.0-Å resolution of the compound in complex with the protein establishes the existence of a previously unidentified allosteric regulatory site. This allosteric site allows for selective inhibition with respect to the homologous human enzyme. We observe a unique binding mode in which two inhibitor molecules interact within the allosteric site, driving significant conformational changes that preclude simultaneous substrate and inhibitor binding. Our results demonstrate the selective inhibition of a highly conserved metabolic enzyme that contains identical active site residues in both the host and the pathogen.
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20850; Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom;
Monica
M
Kasbekar
Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom;
Gerhard
G
Fischer
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20850;
Bryan T
BT
Mott
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20850;
Adam
A
Yasgar
Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom;
Marko
M
Hyvönen
National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20850.
Helena I M
HI
Boshoff
Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom;
Chris
C
Abell
National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20850.
Clifton E
CE
Barry
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20850; craigt@mail.nih.gov.
Craig J
CJ
Thomas
D000494:Allosteric Regulation; D018360:Crystallography, X-Ray; D005453:Fluorescence; D005649:Fumarate Hydratase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000201:enzymology*
D005649:Fumarate Hydratase
Mycobacterium tuberculosis; TCA cycle; allosteric regulation; fumarate hydratase; selective inhibition