Investigation of the interactions between aptamer and misfolded proteins: From monomer and oligomer to fibril by single‐molecule force spectroscopy

Abstract

Increasing knowledge on the understanding interactions of aptamer with misfolded proteins (including monomer, oligomer, and amyloid fibril) is crucial for development of aggregation inhibitors and diagnosis of amyloid diseases. Herein, the interactions of lysozyme monomer-, oligomer-, and amyloid fibril-aptamer were investigated using single-molecule force spectroscopy. The results revealed that the aptamer screened against lysozyme monomer could also bind to oligomer and amyloid fibril, in spite of the recognition at a lower binding probability. It may be attributed to the inherent structural differences of misfolded proteins and the flexible conformation of aptamer. In addition, dynamic force spectra showed that there were similar dissociation paths in the dissociation process of lysozyme monomer-, oligomer-, and amyloid fibril-aptamer complexes. It showed that the dissociation only passed 1 energy barrier from the binding state to the detachment. However, the dynamic parameters suggested that the oligomer- and amyloid fibril-aptamer were more stable than lysozyme monomer-aptamer. The phenomena may result from the exposure of aptamer-recognized sequences on the surface and the electrostatic interactions. This work demonstrated that single-molecule force spectroscopy could be a powerful tool to study the binding behavior of the aptamer with misfolded proteins at single-molecule level, providing abundant information for researches and comprehensive applications of aptamer probes in diagnosis of amyloid diseases.

Investigation of the interaction between split aptamer and vascular endothelial growth factor 165 using single molecule force spectroscopy

“…All force curves were analyzed with JPK image processing. The force maps were measured with a stay time of 0.5 second and a resolution of 32 × 32 pixels on a scan area of 5 μm × 5 μm . The loading rates were changed from 8.77 to 87.7 nN/s for investigating the influence of loading rate on the reaction.…”

“…The force maps were measured with a stay time of 0.5 second and a resolution of 32 × 32 pixels on a scan area of 5 μm × 5 μm. 31 The loading rates were changed from 8.77 to 87.7 nN/s for investigating the influence of loading rate on the reaction. The number of curves analyzed were higher than 3000, which were obtained from three autocephalous experiments for each unbinding force histogram.…”

Research progress of single molecule force spectroscopy technology based on atomic force microscopy in polymer materials: Structure, design strategy and probe modification

“…As shown in Figure 11D, if the gold substrate or the AFM tip was blocked, the specific force peak in the force‐distance curve would disappear. [ 140 ]…”

“…D, Before and after the closed system has been modified by a protein or a free aptamer (the description for Figure 11D see inset figure), representative force curve obtained on a gold substrate with a modified protein by the functionalized probe tip, reprinted with permission from Ref. [ 140 ] Copyright 2018, Wiley‐VCH…”

“…D, Before and after the closed system has been modified by a protein or a free aptamer (the description for Figure 11D see inset figure), representative force curve obtained on a gold substrate with a modified protein by the functionalized probe tip, reprinted with permission from Ref. [140] Copyright 2018, Wiley-VCH of aptamer and misfolded protein. In addition, blocking test and control experiments were utilized to distinguish between specific adhesion and non-specific adhesion.…”