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Updated: Jul 7, 2026
Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
Interaction between the C-terminal region of human myelin basic protein and calmodulin: analysis of complex formation
Viivi Majava1, Maxim V Petoukhov, Nobuhiro Hayashi
1Department of Biochemistry, University of Oulu, Oulu, Finland. viivi.majava@oulu.fi
Insights
Researchers studied the interaction between myelin basic protein peptide and calmodulin, finding they bind with low micromolar affinity. This interaction involves a conformational change in calmodulin, revealing a novel binding mode relevant to the nervous system.
Area of Science:
- Neuroscience
- Biochemistry
- Structural Biology
Background:
- Myelin basic protein (MBP) is crucial for myelin sheath formation and nerve impulse conduction.
- MBP is an intrinsically disordered protein known to interact with calmodulin.
- This study investigates a specific peptide from human MBP's C-terminus binding to calmodulin.
Purpose of the Study:
- To structurally elucidate the interaction between a human myelin basic protein peptide and calmodulin.
- To characterize the binding affinity and mode of interaction between these two key nervous system proteins.
Main Methods:
- Affinity chromatography to confirm MBP-calmodulin interaction.
- Isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) for binding kinetics and thermodynamics.
- NMR spectroscopy and small-angle X-ray scattering (SAXS) for structural mapping and solution structure determination.
Main Results:
- The MBP peptide binds to calmodulin with a dissociation constant (Kd) in the low micromolar range.
- Binding induces a conformational change in calmodulin, with the peptide interacting primarily with the C-terminal lobe.
- SAXS data reveals the peptide binds within the interlobal groove, maintaining calmodulin's extended conformation.
Conclusions:
- The study provides detailed structural insights into the interaction of calmodulin with a C-terminal MBP segment.
- A novel calmodulin-target protein interaction mode is suggested, where calmodulin remains extended.
- The observed binding affinity is physiologically relevant due to the high abundance of MBP and calmodulin in the nervous system.
Background:
The myelin sheath is a multilamellar membrane structure wrapped around the axon, enabling the saltatory conduction of nerve impulses in vertebrates. Myelin basic protein, one of the most abundant myelin-specific proteins, is an intrinsically disordered protein that has been shown to bind calmodulin. In this study, we focus on a 19-mer synthetic peptide from the predicted calmodulin-binding segment near the C-terminus of human myelin basic protein.
Results:
The interaction of native human myelin basic protein with calmodulin was confirmed by affinity chromatography. The binding of the myelin basic protein peptide to calmodulin was tested with isothermal titration calorimetry (ITC) in different temperatures, and Kd was observed to be in the low muM range, as previously observed for full-length myelin basic protein. Surface plasmon resonance showed that the peptide bound to calmodulin, and binding was accompanied by a conformational change; furthermore, gel filtration chromatography indicated a decrease in the hydrodynamic radius of calmodulin in the presence of the peptide. NMR spectroscopy was used to map the binding area to reside mainly within the hydrophobic pocket of the C-terminal lobe of calmodulin. The solution structure obtained by small-angle X-ray scattering indicates binding of the myelin basic protein peptide into the interlobal groove of calmodulin, while calmodulin remains in an extended conformation.
Conclusion:
Taken together, our results give a detailed structural insight into the interaction of calmodulin with a C-terminal segment of a major myelin protein, the myelin basic protein. The used 19-mer peptide interacts mainly with the C-terminal lobe of calmodulin, and a conformational change accompanies binding, suggesting a novel mode of calmodulin-target protein interaction. Calmodulin does not collapse and wrap around the peptide tightly; instead, it remains in an extended conformation in the solution structure. The observed affinity can be physiologically relevant, given the high abundance of both binding partners in the nervous system.
