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

General diffusion porins are passive transmembrane channels. 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. The basic module
was selected by multi-alignment of general diffusion porins. The
sequence corresponded to a highly conserved motif containing two
beta-strands, which was obtained from Escherichia coli OmpF. Dimeric to
octameric repeats were obtained through cDNA recombinant technology. The
hexameric repeat was used to test its properties. This protein was
expressed, purified and reconstituted in the planar bilayer membranes.
It was able to form channels in membranes with a conductance of 300 pS
in 150 mM KCl and did not show any relevant voltage-dependence.