Minimal Nucleation State of alpha-Synuclein Is Stabilized by Dynamic Threonine - Water Networks

作者:Romo Tod D; Lewis Andrew K; Braun Anthony R; Grossfield Alan; Sachs Jonathan N*
来源:ACS Chemical Neuroscience, 2017, 8(9): 1859-1864.
DOI:10.1021/acschemneuro.7b00171

摘要

The first structures of a-synuclein (alpha Syn) fibrils have recently been solved. Here, we use a unique combination of molecular dynamics simulation strategies to address the minimal nucleation size of the 11-amino acid NAC protofibril solved by X-ray and to interrogate the dynamic behavior of unexpected crystal waters in the steric zipper. We found that protofibrils of >8 chains are thermodynamically stabilized due to protection of the fibril core from solvent influx and ordering of the end strands by the fibril core. In these stable oligomers, water molecules resolved in the crystal structure freely exchange with bulk solvent but are, on average, stably coordinated along the beta-sheet by inward-facing Thr72 and Thr75. We confirm the persistence of this water coordination via simulations of the full-length Greek-key structure solved by NMR and speculate that these Thr water networks are important in the context of enhanced fibril nucleation in the familial A53T mutation.

  • 出版日期2017-9