Peptide-induced mycobacterial membrane permeabilization studies to enhance drug uptake.

Anti-tubercular therapy is a long-term process during which the chances of drug resistance are high due to its inaccurate distribution. The bioavailability of the drug is limited due to the pharmacokinetic parameters and cell membrane barriers. Rational designing of the drug is essential to validate the required entry into the target cell to eliminate chances of resistance. Australian frog peptides aurein1.2 and maculatin1.1 have membrane-active properties which could be exploited to enhance the drug uptake in Mycobacterium. This work used a combination of biophysical techniques to study the peptide interaction patterns on mycobacterial cell envelope layers. Atomic force microscopy and surface plasmon resonance studies revealed that aurein1.2 insertion leads to lipid removal in the mycobacterial inner membrane lipids. In contrast, maculatin1.1 insertion leads to the blebbing of the bilayer. Dye-leakage assay performed using confocal microscopy promises aurein1.2 to effectively permeabilize outer and inner mycobacterial membranes, while maculatin1.1 permeabilizes selectively. However, flow cytometry studies indicated greater permeabilization of propidium iodide into the intact Mycobacterium smegmatis when treated with maculatin1.1, indicating the formation of a larger surface area of blebbing compared to the area of lipid removal by aurein1.2. When used in combination with anti-tubercular drugs smaller than the pores formed by the peptides, these molecules can spur up the drug uptake to enhance intracellular drug concentrations. Leveraging the membrane-drug interaction profiles unique to mycobacteria, specific chemotypes consisting of outer membrane-disruptive agents and anti-tubercular drugs may provide strategies for new combinational TB therapies.