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Abstract

Intrinsically disordered proteins experience a diverse spectrum of motions that are difficult to characterize with a single experimental technique. Here we combine high- and low-field nuclear spin relaxation, nanosecond fluorescence correlation spectroscopy (nsFCS) and long molecular dynamics simulations of alpha-synuclein, a paradigmatic IDP involved in Parkinson disease, to obtain a comprehensive picture of its conformational dynamics. The combined analysis shows that fast motions below 2 ns caused by local dihedral angle fluctuations and conformational sampling within and between Ramachandran substates decorrelate most of the backbone N-H orientational memory. However, slow motions with correlation times of up to ~13 ns from segmental dynamics are present throughout the alpha-synuclein chain, in particular in its C-terminal domain, and global chain reconfiguration occurs on a timescale of ~ 60 ns. Our study demonstrates that the combination of high- and low-field nuclear spin relaxation together with nsFCS and molecular dynamics simulations is a powerful strategy to determine residue-specific protein dynamics in IDPs at different time and length scales.