Unfolded states under folding conditions accommodate sequence-specific conformational preferences with random coil-like dimensions
Year: 2019
Type: article
Abstract: Proteins are marginally stable molecules that fluctuate between folded and unfolded states. Here, we provide a high-resolution description of unfolded states under refolding conditions for the N-terminal domain of the L9 protein (NTL9). We use a combination of time-resolved Förster resonance energy transfer (FRET) based on multiple pairs of minimally perturbing labels, time-resolved small-angle X-ray scattering (SAXS), all-atom simulations, and polymer theory. Upon dilution from high denaturant, the unfolded state undergoes rapid contraction. Although this contraction occurs before the folding transition, the unfolded state remains considerably more expanded than the folded state and accommodates a range of local and nonlocal contacts, including secondary structures and native and nonnative interactions. Paradoxically, despite discernible sequence-specific conformational preferences, the ensemble-averaged properties of unfolded states are consistent with those of canonical random coils, namely polymers in indifferent (theta) solvents. These findings are concordant with theoretical predictions based on coarse-grained models and inferences drawn from single-molecule experiments regarding the sequence-specific scaling behavior of unfolded proteins under folding conditions.
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Awards: G1017699072, G102163711, G107546177, IDBR Type A: Optimization of microsecond mixing devices for biological kinetics via simulation and experiment, G1313983767, G1664757510, G2008846556, The Biophysics Collaborative Access Team, G2287611682, Multiscale Modeling of Phase Transitions Driven by Multivalency and Disordered Proteins, G262962599, G3075337988, Elucidating the molecular logic of membrane-free compartment function and assembly, G409777406, Structure, Dynamics and Energetics of Protein Unfolded States, G498139845, G513797252, G5499275266, G5607048534, The molecular basis of islet amyloid induced beta-cell death and the inhibition of islet amyloid induced toxicity, Research Coordination Network: Protein Folding and Dynamics, G6848031779, G6868616705, G6918803902, Folding Mechanisms of Dihydrofolate Reductase and the Response Regulators, G9000275877, G969889393, G993149817
OpenAlex ID: W2948216821