Mechanistic Insight into CM18-Tat(11) Peptide Membrane-Perturbing Action by Whole-Cell Patch-Clamp Recording

The membrane-destabilization properties of the recently-introduced endosomolytic CM18-Tat(11) hybrid peptide (KWKLFKKIGAVLKVLTTG-YGRKKRRQRRR, residues 1-7 of cecropin-A, 2-12 of melittin, and 47-57 of HIV-1 Tat protein) are investigated in CHO-K1 cells by using the whole-cell configuration of the patch-clamp technique. CM18-Tat(11), CM18, and Tat(11) peptides are administered to the cell membrane with a computer-controlled micro-perfusion system. CM18-Tat(11) induces irreversible cell-membrane permeabilization at concentrations (>= 4 mu M) at which CM18 triggers transient pore formation, and Tat(11) does not affect membrane integrity. We argue that the addition of the Tat(11) module to CM18 is able to trigger a shift in the mechanism of membrane destabilization from "toroidal" to "carpet", promoting a detergent-like membrane disruption. Collectively, these results rationalize previous observations on CM18-Tat(11) delivery properties that we believe can guide the engineering of new modular peptides tailored to specific cargo-delivery applications.