Super-resolution Imaging of Amyloid Structures over Extended Times by Using Transient Binding of Single Thioflavin T Molecules

Abstract

<p class="first" id="P1">Oligomeric amyloid structures are crucial therapeutic targets in Alzheimer’s and other amyloid diseases. However, these oligomers are too small to be resolved by standard light microscopy. We have developed a simple and versatile tool to image amyloid structures using Thioflavin T without the need for covalent labeling or immunostaining. Dynamic binding of single dye molecules generates photon bursts that are used for fluorophore localization on a nanometer scale. Thus, photobleaching cannot degrade image quality, allowing for extended observation times. Super-resolution Transient Amyloid Binding (TAB) microscopy promises to directly image native amyloid using standard probes and record amyloid dynamics over minutes to days. We imaged amyloid fibrils from multiple polypeptides, oligomeric, and fibrillar structures formed during different stages of amyloid-β aggregation, as well as the structural remodeling of amyloid-β fibrils by the compound epi-gallocatechin gallate (EGCG). </p><p id="P2"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/a01b6026-d63b-490b-8868-e94b3af40ec8/PubMedCentral/image/nihms-1003734-f0005.jpg"/> </div> </p><p id="P3"> <b>Transient amyloid binding (TAB) imaging</b> resolves amyloid structures at a nanometer scale using standard probes, Thioflavin T (ThT), without the need for covalent modification or immunostaining of amyloids. Binding dynamics and blinking of ThT molecules on amyloids enables continuous imaging over extended times without image degradation due to photobleaching, and gives robust imaging to various amyloid structures and imaging conditions. </p>