Fountain Adam J, Waller Natalie J E, Cheung Chen-Yi, Jowsey William, Chrisp Michael T, Troll Mark, Edelstein Paul H, Cook Gregory M, McNeil Matthew B, Ramakrishnan Lalita
Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom.
Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, Cambridge CB2 0AW, United Kingdom.
Proc Natl Acad Sci U S A. 2025 Apr 22;122(16):e2426827122. doi: 10.1073/pnas.2426827122. Epub 2025 Apr 17.
Bedaquiline is the cornerstone of a new regimen for the treatment of drug-resistant tuberculosis. However, its clinical use is threatened by the emergence of bedaquiline-resistant strains of . Bedaquiline targets mycobacterial ATP synthase but the predominant route to clinical bedaquiline resistance is via upregulation of the MmpS5L5 efflux pump due to mutations that inactivate the transcriptional repressor . Here, we show that the MmpS5L5 efflux pump reduces susceptibility to bedaquiline as well as its new, more potent derivative TBAJ-876 and other antimicrobial substrates, including clofazimine and the DprE1 inhibitors PBTZ-169 and OPC-167832. Furthermore, the increased resistance of mutants stems entirely from increased MmpS5L5 expression. These results highlight the potential of a pharmacological MmpS5L5 inhibitor to increase drug efficacy. Verapamil, primarily used as a calcium channel inhibitor, is known to inhibit diverse efflux pumps and to potentiate bedaquiline and clofazimine activity in . Here, we show that verapamil potentiates the activity of multiple diverse MmpS5L5 substrates. Using biochemical approaches, we demonstrate that verapamil does not exert this effect by acting as a disruptor of the protonmotive force used to power MmpS5L5, as previously proposed, suggesting that verapamil inhibits the function of the MmpS5L5 pump. Finally, norverapamil, the major verapamil metabolite, which has greatly reduced calcium channel activity, has equal potency in reducing resistance to MmpS5L5 substrates. Our findings highlight verapamil's potential for enhancing bedaquiline TB treatment, for preventing acquired resistance to bedaquiline and other MmpS5L5 substrates, while also providing the impetus to identify additional MmpS5L5 inhibitors.
贝达喹啉是治疗耐药结核病新方案的基石。然而，贝达喹啉耐药菌株的出现威胁到了其临床应用。贝达喹啉作用于分枝杆菌ATP合酶，但临床出现贝达喹啉耐药的主要途径是由于使转录阻遏物失活的突变导致MmpS5L5外排泵上调。在此，我们表明MmpS5L5外排泵降低了对贝达喹啉及其新的、更有效的衍生物TBAJ - 876以及其他抗菌底物（包括氯法齐明和DprE1抑制剂PBTZ - 169和OPC - 167832）的敏感性。此外，突变体耐药性增加完全源于MmpS5L5表达的增加。这些结果凸显了药理学上的MmpS5L5抑制剂提高药物疗效的潜力。维拉帕米主要用作钙通道抑制剂，已知其能抑制多种外排泵并增强贝达喹啉和氯法齐明在……中的活性。在此，我们表明维拉帕米增强了多种不同的MmpS5L5底物的活性。通过生化方法，我们证明维拉帕米并非如先前所提出的那样通过作为驱动MmpS5L5的质子动力的破坏剂来发挥这种作用，这表明维拉帕米抑制了MmpS5L5泵的功能。最后，维拉帕米的主要代谢产物去甲维拉帕米，其钙通道活性已大幅降低，但在降低对MmpS5L5底物的耐药性方面具有同等效力。我们的研究结果凸显了维拉帕米在增强贝达喹啉治疗结核病方面的潜力，在预防对贝达喹啉和其他MmpS5L5底物获得性耐药方面的潜力，同时也为鉴定其他MmpS5L5抑制剂提供了动力。
