Exploring Tau Conformations at the Single-Molecule Level in a Microfluidic Trap

The conformational dynamics of intrinsically disordered proteins (IDP's) are inextricably linked to their roles in signaling, regulation, folding, and diseases. Single-molecule methods can contribute valuable information on the conformational dynamics of biomolecules because they allow the observation of unsynchronized dynamics and characterization of diverse populations. Typically, target biomolecules are immobilized to allow study over a longer time window. However, biomolecules with more fluid structures, like IDP's, are highly susceptible to having their structure dominated by the immobilization environment. A method of studying single solution-phase biomolecules for prolonged periods of time would be highly useful for elucidating protein dynamics over many timescales.In this study, we present the use of a microfluidic trap that is capable of canceling Brownian motion to allow the observation of solution-phase dynamics of IDP's over multiple seconds. We will focus on Tau, a protein contributor to the etiology of Alzheimer's disease. Solution-phase conformations of the monomer and small aggregates will be described. The details of the technique, dynamics of the biomolecule targets, and future applications and directions will be discussed.