Dynamical structure of αB-crystallin

The human small heat-shock protein alphaB-crystallin is an extremely difficult molecule to study, with its inherent structural dynamics posing unique challenges to all biophysical and structural biology techniques. Here we highlight how the polydispersity and quaternary dynamics of alphaB-crystallin are intrinsically inter-twined, and how this can impact on measurements of the oligomeric distribution. We show that, in spite of these difficulties, considerable understanding of the varied fluctuations alphaB-crystallin undergoes at equilibrium has emerged in the last few years. By reporting on data obtained from a variety of biophysical techniques, we demonstrate how the alphaB-crystallin solution ensemble is governed by molecular motions of varying amplitude and time-scales spanning several orders of magnitude. We describe how these diverse measurements are being used to construct an integrated view of the dynamical structure of alphaB-crystallin, and highlight areas that require further interrogation. With its study motivating the refinement of experimental techniques, and the development of new approaches to combine the hybrid datasets, we conclude that alphaB-crystallin continues to represent a paradigm for dynamical biology.