PNNL

Abstract

Naturally occurring membrane protein pores composed of polypeptide chains that fold into 3-dimensional structures dictated by their sequences can perform a wide variety of functions. Synthetic de novo designed membrane pores could open up almost limitless array of possibilities for new functionality. Here we explore water, solute and ion transport in two de novo designed beta-barrel membrane channels in the 5-10 Å pore size range. We show that these proteins form passive membrane pores with high water transport efficiencies and size rejection characteristics consistent with the pore size encoded into the protein structure. Ion conductance measurements and ion selectivity measurements also show trends consistent with the pore size, with both pores showing weak cation selectivity. MD simulations of water and ion transport and solute size exclusion are consistent with the experimental trends and provide further insights into structure-function correlations in these membrane pores.