Real-time topological changes and simultaneous electrical recordings of polycystin-2 (TRPP2) with a combined lipid bilayer-atomic force microscopy platform.

CANTERO MR; CANTIELLO HF

Congreso; Reunión Conjunta de Sociedades de Biociencias.; 2017

Ion channels are transmembrane proteins that mediate ion transport across biological membranes. Ion channels are traditionally characterized by electrical parameters acquired with techniques such as patch-clamping and reconstitution in lipid bilayer membranes (BLM). High resolution structural information of ion channels requires independent technologies, of which atomic force microscopy (AFM) is the only one that provides topological information on functional channel proteins in their native environments. To date, however, no direct correlations exist between electrical features and identifiable structural parameters from functional single channel complexes. The present study reports on preliminary data of polycystin-2 (TRPP2, PC2) channel function and topological features from single channel complexes studied in a platform containing a BLM reconstitution microchamber and an AFM imaging unit. To correlate single channel currents with the topological features of identifiable channel complexes, we simultaneously collected AFM scans and BLM electrical recordings in identifiable single channel complexes. Simultaneous single channel currents and AFM images were matched for the same collection times. Matched data showed an inverse linear correlation between the relative height of the channel complex, and the single channel currents, with a slope of -7.63 ± 1.2 pA/nm, n = 5, (r = 0.9862). The observations were confirmed with a second approach where the PC2 single channel currents collected in the BLM system were directly fed into an I/O analog port of the AFM controller. Again we observed an inverse linear correlation between the two features with a slope of -8.07 ± 0.35 pA/nm, n = 3 (r = 0.9642). The present study provides direct structural-functional correlations from single PC2 channel complexes disclosing topological changes between the open and closed states of the functional channel.Key words: Ion channels, atomic force microscopy, polycystin-2