Local Mechanical Perturbation Provides an Effective Means to Regulate the Growth and Assembly of Functional Peptide Fibrils

Abstract

Mucin 1 (MUC1) peptide fused with Q11 (MUC1-Q11) having 35 residues has previously been shown to form amyloid fibrils. Using time-dependent and high-resolution atomic force microscopy (AFM) imaging, it is revealed that the formation of individual MUC1-Q11 fibrils entails nucleation and extension at both ends. This process can be altered by local mechanical perturbations using AFM probes. This work reports two specific perturbations and outcomes. First, by increasing load while maintaining tip-surface contact, the fibrils are cut during the scan due to shearing. Growth of fibrils occurs at the newly exposed termini, following similar mechanism of the MUC1-Q11 nucleation growth. As a result, branched fibrils are seen on the surface whose orientation and length can be controlled by the nuclei orientation and reaction time. In contrast to the "one-time-cut", fibrils can be continuously fragmented by modulation at sufficiently high amplitude. As a result, short and highly branched fibrils accumulate and pile on surfaces. Since the fibril formation and assembly of MUC1-Q11 can be impacted by local mechanical force, this approach offers a nonchemical and label-free means to control the presentation of MUC1 epitopes, and has promising application in MUC1 fibril-based immunotherapy.

Impact of membrane curvature on amyloid aggregation

“…The hierarchical structures of amyloid fibrils elucidated using X-ray crystallography and solid-state NMR spectroscopy appear to be very stable [125–129]; however, amyloid fibrils showed nearly complete denaturation (i.e., depolymerization or dissociation) to monomers or other types of aggregates. External perturbations, including temperature [119, 122], chemical denaturants [130, 131], pressure [65, 66], mechanical perturbation [132], and the presence of additives, including polyphenols [133, 134], destabilized and denatured amyloid fibrils (several tens of kJ mol −1 of a change in Gibbs free energy) (Fig. 9).…”

Direct Visualization of the Binding of Transforming Growth Factor Beta 1 with Cartilage Oligomeric Matrix Protein via High-Resolution Atomic Force Microscopy

“…We investigated the interaction of TGF-β1 and COMP by comparing high-resolution AFM images of the COMP, TGF-β1, and their mixtures after immobilization onto mica(0001) surfaces. Mica(0001) surfaces were chosen as the support because they are atomically flat structures. ,,, In Figure , the characteristic AFM topographical images for all three systems are displayed side-by-side, using the same scanning size of 500 × 500 nm 2 .…”

“…Mica(0001) surfaces were chosen as the support because they are atomically flat structures. 4,22,28,29 In Figure 1, the characteristic AFM topographical images for all three systems are displayed side-by-side, using the same scanning size of 500 × 500 nm 2 .…”

“…Mica(0001) surfaces were chosen as the support because they are atomically flat structures. 4,22,28,29 In Figure 1, the characteristic AFM topographical images for all three systems are displayed side-by-side, using the same scanning size of 500 x 500 nm 2 In Figure 1A, 100 βl of 2 nM COMP solution was deposited onto mica(0001) for 2 minutes, followed by washing with milli-Q water and drying with compressed air before AFM imaging. Individual COMP molecules were clearly separated and visualized.…”

In Situ Atomic Force Microscopy Studies on Nucleation and Self-Assembly of Biogenic and Bio-Inspired Materials

“…Although AFM imaging force is normally kept small to prevent sample damage, people can also apply a higher force to initiate new events. Liu's group used an AFM probe to mechanically cut the amyloid fibrils, which are formed by mucin 1 peptide fused with Q11 (MUC1-Q11), and observed growth of fibrils at the newly exposed termini using in situ AFM [148]. They showed that orientation and length of branched fibrils can be controlled by the nuclei orientation and reaction time.…”