title: Probing the interaction of the diarylquinoline TMC207 with its target mycobacterial ATP synthase.
abstract: Infections with Mycobacterium tuberculosis are substantially increasing on a worldwide scale and new antibiotics are urgently needed to combat concomitantly emerging drug-resistant mycobacterial strains. The diarylquinoline TMC207 is a highly promising drug candidate for treatment of tuberculosis. This compound kills M. tuberculosis by binding to a new target, mycobacterial ATP synthase. In this study we used biochemical assays and binding studies to characterize the interaction between TMC207 and ATP synthase. We show that TMC207 acts independent of the proton motive force and does not compete with protons for a common binding site. The drug is active on mycobacterial ATP synthesis at neutral and acidic pH with no significant change in affinity between pH 5.25 and pH 7.5, indicating that the protonated form of TMC207 is the active drug entity. The interaction of TMC207 with ATP synthase can be explained by a one-site binding mechanism, the drug molecule thus binds to a defined binding site on ATP synthase. TMC207 affinity for its target decreases with increasing ionic strength, suggesting that electrostatic forces play a significant role in drug binding. Our results are consistent with previous docking studies and provide experimental support for a predicted function of TMC207 in mimicking key residues in the proton transfer chain and blocking rotary movement of subunit c during catalysis. Furthermore, the high affinity of TMC207 at low proton motive force and low pH values may in part explain the exceptional ability of this compound to efficiently kill mycobacteria in different microenvironments.
authors.affiliation: Department of Molecular Cell Biology, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Haagsma
authors.forename: Ioana
authors.initials: I
authors.lastname: Podasca
authors.forename: Anil
authors.initials: A
authors.lastname: Koul
authors.forename: Koen
authors.initials: K
authors.lastname: Andries
authors.forename: Jerome
authors.initials: J
authors.lastname: Guillemont
authors.forename: Holger
authors.initials: H
authors.lastname: Lill
authors.forename: Dirk
authors.initials: D
authors.lastname: Bald
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D000995:Antitubercular Agents / Q000737:chemistry / Q000378:metabolism; D025243:Bacterial Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive / Q000187:drug effects; D064687:Diarylquinolines; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000201:enzymology*; D009570:Nitriles / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018892:Proton-Motive Force; D011522:Protons; D011804:Quinolines / Q000737:chemistry / Q000378:metabolism*; D055672:Static Electricity; D020349:Surface Plasmon Resonance
chemical_list: D000995:Antitubercular Agents; D064687:Diarylquinolines; D007476:Ionophores; D009570:Nitriles; D021122:Protein Subunits; D011522:Protons; D011804:Quinolines; C001784:SF 6847; C493870:bedaquiline; D000255:Adenosine Triphosphate; D025243:Bacterial Proton-Translocating ATPases