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Functional properties of calbindin D9K mutants with exchanged Ca2+ binding sites
P Brodin1, C Johansson, S Forsén
1Department of Applied Cell and Molecular Biology, University of Umeå, Sweden.
The Journal of Biological Chemistry
|July 5, 1990
Summary
Engineered calbindin proteins with modified calcium binding sites retain strong calcium binding affinity. These structural modifications demonstrate the robustness of calcium-binding protein design.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Engineering
Background:
- Calbindin D9K is a calcium-binding protein with two EF-hand motifs.
- Understanding the structure-function relationship of calcium-binding sites is crucial for protein engineering.
Purpose of the Study:
- To engineer calbindin D9K by altering its calcium binding sites.
- To investigate the impact of these alterations on calcium binding affinity and structural integrity.
Main Methods:
- Construction of three engineered calbindin D9K variants.
- Modification involved site-exchanging or identical amino acid sequencing of calcium binding sites.
- Analysis of ion binding characteristics and Ca2+ ligand sphere structure.
Main Results:
- Engineered proteins largely retained ion binding characteristics.
- The basal structure of the Ca2+ ligand sphere remained intact in the new environment.
- An engineered protein with interchanged sites (30/75 amino acids altered) exhibited high calcium binding affinity.
Conclusions:
- The calcium binding sites of calbindin D9K are robust to significant engineering.
- Structural modifications, including site interchange, do not abolish high-affinity calcium binding.
- This work provides insights into the design principles of calcium-binding proteins.