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Exploring the Impact of Physiological C-Terminal Truncation on α-Synuclein Conformations to Unveil Mechanisms Regulating Pathological Aggregation

<p><span>Emerging evidence suggests that <a name="_Hlk179101300"></a>physiological C-terminal truncation of &alpha;-synuclein (&alpha;S) plays a critical role in regulating <a name="_Hlk178755669"></a>liquid&ndash;liquid phase separation and promoting amyloid aggregation, processes implicated in neurodegenerative diseases such as Parkinson&rsquo;s disease (PD). However, the molecular mechanisms through which C-terminal truncation influences &alpha;S conformation and modulates its aggregation remain poorly understood. In this study, we investigated the impact of C-terminal truncation on &alpha;S conformational dynamics by comparing full-length &alpha;S<sub>1-140</sub> with truncated &alpha;S<sub>1-103</sub> monomers using atomistic discrete molecular dynamics (DMD) simulations. Our findings revealed that both &alpha;S<sub>1-140</sub> and &alpha;S<sub>1-103</sub> primarily adopted helical conformations around residues 7&ndash;32, while residues 35-95, located in the second half of the N-terminal and NAC domains, predominantly formed a dynamic &beta;-sheet core. The C-terminus of &alpha;S<sub>1-140</sub> was largely unstructured and dynamically wrapped around the &beta;-sheet core. While residues 1-95 exhibited similar secondary structure propensities in both &alpha;S<sub>1-140</sub> and &alpha;S<sub>1-103</sub>, the dynamic capping by the C-terminus in &alpha;S<sub>1-140</sub> slightly enhanced &beta;-sheet formation around residues 35-95. In contrast, key aggregation-driving regions (residues 2-9, 36-42, 45-57, and 68-78) were dynamically shielded by the C-terminus in &alpha;S<sub>1-140</sub>, reducing their exposure and potentially preventing inter-peptide interactions that drive aggregation. C-terminal truncation, on the other hand, increased the exposed surface area of these aggregation-prone regions, thereby enhancing inter-peptide interactions, phase separation, and amyloid aggregation. Overall, our simulations provide valuable insights into the conformational effects of C-terminal truncation on &alpha;S and its role in promoting pathological aggregation.</span></p>

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32/100

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4
Harmonization
4
Access
16
Reuse readiness
8
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0