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Local and long-range stability in tandemly arrayed tetratricopeptide repeats
Ewan R G Main1, Katherine Stott, Sophie E Jackson
1Department of Molecular Biophysics, Yale University, 266 Whitney Avenue, New Haven, CT 06520, USA.
Summary
Designed tetratricopeptide repeat (TPR) proteins demonstrate stable folding and a defined core structure. Their stability correlates with the number of TPR repeats, offering insights into protein design and function.
Area of Science:
- Protein Engineering
- Structural Biology
- Biophysics
Background:
- Tetratricopeptide repeats (TPR) are common alpha-helical motifs in proteins, forming tandem arrays that act as molecular scaffolds and mediate protein-protein interactions.
- Natural TPR proteins contain 3 to 16 or more TPR motifs.
Purpose of the Study:
- To investigate the thermodynamic properties and folding kinetics of designed TPR proteins (CTPR1, CTPR2, CTPR3).
- To understand how the number of tandem TPR repeats influences protein stability and folding.
- To validate the design of TPR proteins based on an idealized consensus motif.
Main Methods:
- Chemical denaturation monitored by Circular Dichroism (CD) and fluorescence spectroscopy to assess global stability.
- Nuclear Magnetic Resonance (NMR)-detected amide proton exchange to probe residue-specific stability.
- High-resolution crystal structure analysis of designed TPR proteins.
Main Results:
- Designed TPR proteins adopt the canonical TPR fold, confirmed by crystal structures.
- A stable core structure was identified within individual TPR motifs, contributing to overall protein stability.
- Protein stability and folding characteristics were found to be dependent on the number of tandem TPR repeats.
Conclusions:
- Designed TPR proteins exhibit predictable folding and stability based on their consensus motif and repeat number.
- The study validates the strategy of designing functional TPR domains using idealized repeats.
- Findings provide a foundation for understanding the relationship between sequence, structure, stability, and folding in TPR proteins.