Disulfide-Bond-Induced Structural Frustration and Dynamic Disorder in a Peroxiredoxin from MAS NMR

Area of Science:

• Biochemistry and Molecular Biology
• Protein Dynamics and Structure
• Cellular Redox Regulation

Background:

• Disulfide bonds are crucial for protein structure and intracellular oxidation state regulation.
• Peroxiredoxins (PRDXs) detoxify reactive oxygen species via a catalytic cycle involving cysteine oxidation and reduction.
• PRDXs undergo conformational changes, including oligomerization, upon cysteine oxidation, potentially mediating chaperone functions.

Purpose of the Study:

• To investigate the impact of disulfide bond formation on the dynamics of PRDXs.
• To elucidate the structural basis of PRDXs' poorly understood chaperone activities.
• To understand the timescale and nature of conformational rearrangements in PRDXs.

Main Methods:

• Magic-angle spinning (MAS) NMR spectroscopy on the 216 kDa Tsa1 decameric assembly.
• Solution-NMR spectroscopy on a designed dimeric PRDX mutant.
• Analysis of protein dynamics on the microsecond (μs) timescale.

Main Results:

• Disulfide bond formation during the PRDX catalytic cycle induces extensive μs-timescale dynamics.
• Conformational dynamics were observed in both large decameric and designed dimeric PRDX assemblies.
• These dynamics are attributed to structural frustration, arising from competing constraints on protein mobility.

Conclusions:

• Disulfide bond formation in PRDXs is a key driver of significant protein dynamics.
• Structural frustration explains the observed conformational flexibility despite disulfide bond constraints.
• These findings provide a structural basis for understanding PRDXs' roles in redox regulation and molecular chaperoning.