Mutation-induced change in chignolin stability from π-turn to α-turn
Yutaka Maruyama1, Shunpei Koroku2, Misaki Imai3
1Architecture Development Team, FLAGSHIP 2020 Project, RIKEN Center for Computational Science Kobe 650-0047 Japan.
Mutating the 8th residue of chignolin to neutral amino acids stabilizes the misfolded state. This peptide engineering strategy successfully created stable misfolded structures, demonstrating control over protein folding pathways.
Area of Science:
- Protein folding dynamics
- Computational biophysics
- Peptide structure-function relationships
Background:
- Chignolin exhibits two stable states: native (π-turn) and misfolded (α-turn).
- Previous studies indicated Thr8 is crucial for native state stability via hydrogen bonding.
- The misfolded state does not involve Thr8 in stabilization.
Purpose of the Study:
- To investigate the effect of mutating the 8th residue (Thr8) on chignolin's native and misfolded states.
- To test the hypothesis that mutating Thr8 to neutral residues stabilizes the misfolded structure.
- To explore the conformational behavior of mutants, particularly T8P, using molecular dynamics and NMR.
Main Methods:
- Performed 4 μs molecular dynamics simulations for 19 mutants of the 8th residue.
- Analyzed the structural stability of native and misfolded states under various conditions.
- Utilized Nuclear Magnetic Resonance (NMR) spectroscopy for mutant analysis.
Main Results:
- Mutants T8I, T8F, T8P, T8N, and T8Y exclusively formed the misfolded structure at room temperature.
- The T8P mutant did not form the native structure even at high temperatures due to steric hindrance from proline.
- The T8P mutant exhibited trans and cis conformations at high temperatures, with the trans conformation linked to the misfolded state.
Conclusions:
- Mutation of Thr8 to neutral residues is an effective strategy to stabilize the misfolded state of chignolin.
- Steric hindrance from proline in the T8P mutant prevents native structure formation.
- Conformational flexibility in Gly7-Pro8 is key to understanding the misfolded state's dynamics.
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