Generation of artificial channels by multimerization of β-strands from natural porin

General diffusion porins are passive transmembrane channels in which the transport rate of solutes is proportional to the electrochemical gradient. During the last decade the underlying principles in biological filtering have been transferred to biotechnological application. For this goal bacterial porins and eukaryotic voltage-dependent anion-selective channels (VDAC) are particular interesting due to their stability. We have explored the possibility to create artificial nanopores starting from natural beta-barrel structures. Structural elements of bacterial porins were used to build a series of artificial nanopores whose diameter could be predicted by the number of repeated basic modules present in their composition. The basic module was selected by multi-alignment of general diffusion porins. The sequence corresponds to a highly conserved motif containing amino acids forming two beta strands and their connections, which was obtained from Escherichia coli OmpF. Dimeric to heptameric repeats of the module were obtained through cDNA recombinant technology. The hexameric repeat, comprising 12 predicted beta-strands, was used to test the properties of the construct. The corresponding protein was expressed, purified and tested reconstituted in the planar bilayer membranes. Preliminary results demonstrated that this artificial pore is able to form channels in membranes.