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Amide exchange shows calcium-induced conformational changes are transmitted to the dimer interface of S100B
Nicole M Marlatt1, Gary S Shaw
1Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1.
Biochemistry
|June 1, 2007
Summary
This study reveals how calcium binding alters the structure of S100B protein. Calcium binding destabilizes the dimer interface, impacting protein interactions and conformational changes.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Dynamics
Background:
- S100B is a calcium-binding protein involved in various cellular processes.
- It forms a homodimer with EF-hands and undergoes conformational changes upon calcium binding.
- These changes expose hydrophobic residues, mediating interactions with target molecules.
Purpose of the Study:
- To investigate the calcium-sensitive conformational changes in S100B.
- To elucidate the role of amide exchange rates in apo- and Ca-S100B.
- To compare S100B's calcium-induced changes with monomeric S100 proteins.
Main Methods:
- Fast 1H-15N HSQC experiments.
- Water-transfer methods to monitor amide exchange.
- Comparison with chemical denaturation and monomeric S100 protein data.
Main Results:
- In apo-S100B, helix III shows lower protection factors than other helices.
- Calcium binding decreases protection factors for helices I and IV, indicating dimer interface destabilization.
- Helix II protection factors increase, suggesting reduced surface exposure.
Conclusions:
- Calcium binding to S100B alters dimer interface stability and helix exposure.
- A balance in amide exchange rates between helices II and III is maintained, distinct from monomeric proteins.
- These findings highlight the mechanism of calcium-induced conformational changes in S100B.
