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Functionally accepted insertions of proteins within protein domains
B Collinet1, M Herve, F Pecorari
1Laboratoire de Modélisation et d'Ingénierie des Protéines, EP1088 Université de Paris-Sud, F-91405 Orsay Cedex, France.
The Journal of Biological Chemistry
|April 5, 2000
Summary
Protein structures tolerate large folded insertions, challenging the need for sequence continuity in domain folding. This opens new avenues for screening folded proteins in randomized sequences.
Area of Science:
- Protein Engineering
- Structural Biology
- Biochemistry
Background:
- Protein domains are typically considered continuous sequences essential for proper folding.
- Understanding the limits of protein structural tolerance to insertions is crucial for protein design.
Purpose of the Study:
- To investigate the tolerance of protein structure and folding to large, folded protein insertions within a structural domain.
- To assess the functionality of chimeric proteins composed of multiple folded domains.
Main Methods:
- Insertion of two model proteins, dihydrofolate reductase and beta-lactamase, into four different positions of phosphoglycerate kinase.
- Overexpression and functional analysis of the resulting chimeric proteins.
Main Results:
- All generated chimeric proteins were successfully overexpressed.
- Both the host (phosphoglycerate kinase) and the inserted proteins (dihydrofolate reductase, beta-lactamase) retained their functionality.
- Functional coupling between fused protein partners was observed in some chimeras, though not explicitly designed.
Conclusions:
- Protein structures exhibit a greater tolerance to large, folded insertions than previously anticipated.
- The natural sequence continuity of a structural domain is not a prerequisite for the folding process.
- These findings suggest novel experimental strategies for screening folded proteins within randomized polypeptide sequences.