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Conformation of bovine myelin basic protein purified with bound lipids
E Polverini1, A Fasano, F Zito
1Istituto Nazionale per la Fisica della Materia, Università di Parma, Italy. paolo.cavatorta@fis.unipr.it
Abstract:
The basic protein of myelin (called MBP) is an extrinsic protein of the myelin membrane. Its structure and function are still unknown. MBP has been extensively studied in its water-soluble form, but it is also known in a detergent-soluble form, which is purified with endogenous myelin lipids and should correspond to the native form of the protein in the membrane. In order to acquire insight into the structure of MBP, we have carried out circular dichroism (CD) experiments on the protein both in the lipid-free and in the lipid-bound form. Our data clearly show that lipid-free MBP is mainly disordered with only a small amount having alpha-helix and beta-sheet motifs. On the other hand, the lipid-bound form of MBP appears to have a consistent amount of ordered secondary structure. Theoretical predictions, made using different computational methods, substantially confirm the tendency of the protein to assume an ordered secondary structure in accordance with our CD results.
Insights
The basic protein of myelin (MBP) is mostly disordered when free of lipids. However, MBP gains ordered structure when bound to myelin lipids, suggesting lipids are crucial for its native conformation.
Area of Science:
- Neuroscience
- Biochemistry
- Structural Biology
Background:
- The basic protein of myelin (MBP) is essential for myelin membrane structure.
- MBP's native structure and function remain largely unknown.
- MBP exists in both water-soluble and lipid-bound (native) forms.
Purpose of the Study:
- To investigate the secondary structure of MBP in its lipid-free and lipid-bound states.
- To understand how lipid binding influences MBP's structural conformation.
Main Methods:
- Circular dichroism (CD) spectroscopy was used to analyze MBP structure.
- Experiments were conducted on both lipid-free and lipid-bound MBP.
- Computational methods were employed for theoretical structure prediction.
Main Results:
- Lipid-free MBP exhibited predominantly disordered structure with minimal alpha-helix and beta-sheet content.
- Lipid-bound MBP demonstrated a significant increase in ordered secondary structure.
- Computational predictions corroborated the CD data, supporting lipid-induced structural ordering.
Conclusions:
- Lipid binding induces a more ordered secondary structure in MBP.
- This finding provides insight into the native conformation of MBP within the myelin membrane.
- Understanding MBP's structure is key to elucidating its function in myelin.