Mapping intramolecular distances of the 18.5-kDa Myelin Basic Protein under various conditions by Förster Resonance Energy Transfer

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Anonna, Prioti

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University of Guelph


The predominant 18.5-kDa isoform of Myelin Basic Protein (MBP) is essential for the development of myelin in the central nervous system (CNS), and is hyper-deiminated in multiple sclerosis. We have previously obtained intramolecular distances between several single Cys-substituted sites in unmodified and pseudo-deiminated MBP variants, and a single internal Trp residue, by Förster Resonance Energy Transfer (FRET). I have obtained additional constraints by FRET of fluorophores attached to double- and single-Cys-substituted residues in the presence of dodecylphosphocholine (DPC) and Zn2+ (to mimic the myelin membrane per se). The quenching of Trp fluorescence by the acceptor showed that Zn2+ in the presence of DPC at its critical micelle concentration of 1.25 mM affected MBP’s local tertiary fold, but FRET distances indicated a negligible effect on global structure. We showed that DPC, like trifluoroethanol (TFE), caused slight compaction and extension. No significant differences between the two variants were seen.



multiple sclerosis, myelin basic protein, FRET