Enzyme activation by urea reveals the interplay between conformational dynamics and substrate binding: a single-molecule FRET study.

Proteins often harness extensive motions of domains and subunits to promote their function. Deciphering how these movements impact activity is key for understanding life's molecular machinery. The enzyme adenylate kinase is an intriguing example for this relationship; it ensures efficient catalysis by large-scale domain motions that lead to the enclosure of the bound substrates ATP and AMP.

NMR and Single-Molecule FRET Insights into Fast Protein Motions and Their Relation to Function.

Proteins often undergo large-scale conformational transitions, in which secondary and tertiary structure elements (loops, helices, and domains) change their structures or their positions with respect to each other. Simple considerations suggest that such dynamics should be relatively fast, but the functional cycles of many proteins are often relatively slow. Sophisticated experimental methods are starting to tackle this dichotomy and shed light on the contribution of large-scale conformational dynamics to protein function.

Single-molecule FRET probes allosteric effects on protein-translocating pore loops of a AAA+ machine.

AAA+ proteins (ATPases associated with various cellular activities) comprise a family of powerful ring-shaped ATP-dependent translocases that carry out numerous vital substrate-remodeling functions. ClpB is a AAA+ protein disaggregation machine that forms a two-tiered hexameric ring, with flexible pore loops protruding into its center and binding to substrate proteins. It remains unknown whether these pore loops contribute only passively to substrate-protein threading or have a more active role.

From Microstates to Macrostates in the Conformational Dynamics of GroEL: A Single-Molecule Förster Resonance Energy Transfer Study.

The chaperonin GroEL is a multisubunit molecular machine that assists in protein folding in the cytosol. Past studies have shown that GroEL undergoes large allosteric conformational changes during its reaction cycle. Here, we report single-molecule Förster resonance energy transfer measurements that directly probe the conformational transitions of one subunit within GroEL and its single-ring variant under equilibrium conditions.