Mutually Exclusive Interactions of Rifabutin with Spatially Distinct Mycobacterial Cell Envelope Membrane Layers Offer Insights into Membrane-Centric Therapy of Infectious Diseases

The mycobacterialcell envelope has spatially resolved inner andouter membrane layers with distinct compositions and membrane properties.However, the functional implication and relevance of this organizationremain unknown. Using membrane biophysics and molecular simulations,we reveal a varied interaction profile of these layers with antibioticRifabutin, underlined by the structural and chemical makeup of theconstituent lipids. The mycobacterial inner membrane displayed thehighest partitioning of Rifabutin, which was located exclusively inthe lipid head group/interfacial region. In contrast, the drug exhibitedspecific interaction sites in the head group/interfacial and hydrophobicacyl regions within the outer membrane. Altogether, we show that thedesign of membrane-active agents that selectively disrupt the mycobacterialouter membrane structure can increase drug uptake and enhance intracellulardrug concentrations. Exploiting the mycobacterium-specific membrane-druginteraction profiles, chemotypes consisting of outer membrane-disruptiveagents and antitubercular drugs can offer new opportunities for combinationaltuberculosis (TB) therapy.