Kupyaphores─Self-Assembling Diisocyanolipopeptide ZnII Ionophores in Mycobacterium tuberculosis ZnII/CuI/II Homeostasis and Antibacterial Effects

Abstract

Mycobacterium tuberculosis (Mtb), the leading cause of infectious disease mortality from a single pathogen, requires essential metal ions to establish infection and persist in the host. Kupyaphores, a suite of recently identified amphiphilic diisocyanolipopeptides, were reported to assist with ZnII acquisition to support a multitude of ZnII-dependent metalloenzymes critical for Mtb’s survival and pathogenicity. However, compared to well-studied FeIII acquisition systems in Mtb, the mechanisms for ZnII acquisition and homeostasis remain virtually unexplored. Herein, we reveal them as novel metal ionophores in Mtb’s metal-fluctuating lipidic niche. A concise modular scalable synthesis was developed to assess the critical features required for activity. Synthetic kupyaphores were structurally and functionally validated, respectively, via LCMS and chemical complementation of kupyaphore-deficient (Δrv0101) Mtb. MS, NMR, and IR evidence demonstrated that kupyaphores complex ZnII as a bidentate ligand. Fluorescence competition data indicated ZnII/CuI/II binding capabilities, by which Mtb entraps excessive metals within o/w-type micelles against host-induced metal intoxication. The inhibition against Gram-positive Staphylococcus aureus and the low human toxicity imply the potential as a novel antibacterial scaffold. Collectively, this work provides insight into the ZnII/CuI/II homeostasis of Mtb and a chemical basis for the development of mechanistic tools, therapeutic conjugates against Mtb, and antibiotics.