Pneumolysin nanopores with a 20 nm diameter characterize the size and shape of individual Tau oligomers
TL;DR
The self-assembly of 35 ± 5 monomers of the pneumolysin (PLY) toxin into stable transmembrane pores with diameters of 20.2 ± 3.0 nm is reported, and excellent low noise characteristics in the context of nanopore-based resistive pulse recordings are reported.
Abstract
Protein nanopores enable the characterization of single proteins in solution without labeling by monitoring the pore’s electrical resistance when protein analytes enter their lumen. A long-standing challenge with biological nanopores, however, is that proteins in their folded conformation are often too large to enter these pores. Here, we report the self-assembly of 35 ± 5 monomers of the pneumolysin (PLY) toxin into stable transmembrane pores with diameters of 20.2 ± 3.0 nm, effective lengths of 9.5 nm, and excellent low noise characteristics in the context of nanopore-based resistive pulse recordings. The exceptionally large diameter of PLY pores enables the characterization of the size and shape of individual proteins, protein complexes, and amyloid oligomers with molecular weights ranging from 50 to 660 kDa. Using PLY nanopores, we followed Tau protein oligomerization in solution by revealing molecular weight, aggregation number, approximate shape, and oligomer concentration over time. At least four characteristics make PLY nanopores attractive for the analysis of heterogeneous amyloid oligomer samples; they: 1) provide stable open pore current with high signal-to-noise ratio; 2) enable label-free analyses of single oligomers without clogging; 3) detect a range of amyloid oligomer sizes, shapes, and aggregation numbers; and 4) reveal the concentration of each oligomer subpopulation.
