Letter to the Editor: Backbone resonance assignments of the 18.5 kDa isoform of murine myelin basic protein (MBP)

Myelin basic protein (MBP) is a family of developmentally-regulated and translocatable isoforms involved in formation of the myelin sheath of the central nervous system (Campagnoni and Skoff, 2001). The 18.5 kDa isoform of MBP is the most common in adult humans and exists as a series of highly post-translationally modified charge isomers (Kim et al., 2003). The in vivo environment of this isoform is the major dense line of myelin, where it maintains the cytoplasmic leaflets of the oligodendrocyte membrane in close apposition. Deiminated MBP is a candidate autoantigen in multiple sclerosis. Other MBP isoforms potentially have roles in signalling pathways during myelin development, yet our understanding of these phenomena is limited by the lack of detailed structural knowledge. All MBP isoforms are ‘intrinsically unstructured’ to facilitate their interactions with diverse ligands (Hill et al., 2002). The protein is primarily a flexible coil in aqueous solution, but attains ordered secondary structure in the presence of detergents and lipids, as well as in organic solvents such as trifluorethanol (TFE) (Liebes et al., 1975). Recently, site-directed spin labelling and electron paramagnetic resonance experiments on a recombinant form of the 18.5 kDa isoform of murine MBP (rmMBP, 176 residues, Mr 19421.5 Da) in protein-vesicle pellets have defined how different regions of the protein interact with myelin-like membranes (Bates et al., 2004). We have turned to solution NMR in order to define its tertiary struc∗To whom correspondence should be addressed. E-mail: gharauz@uoguelph.ca. ture, and present here the first NMR assignment of the backbone of uniformly 13C15N-labelled rmMBP.