Structural and Functional Characterization of Human Peripheral Nervous System Myelin Protein P2

Abstract

The myelin sheath is a tightly packed multilayered membrane structure insulating selected axons in the central and the peripheral nervous systems. Myelin is a biochemically unique membrane, containing a specific set of proteins. In this study, we expressed and purified recombinant human myelin P2 protein and determined its crystal structure to a resolution of 1.85 Å. A fatty acid molecule, modeled as palmitate based on the electron density, was bound inside the barrel-shaped protein. Solution studies using synchrotron radiation indicate that the crystal structure is similar to the structure of the protein in solution. Docking experiments using the high-resolution crystal structure identified cholesterol, one of the most abundant lipids in myelin, as a possible ligand for P2, a hypothesis that was proven by fluorescence spectroscopy. In addition, electrostatic potential surface calculations supported a structural role for P2 inside the myelin membrane. The potential membrane-binding properties of P2 and a peptide derived from its N terminus were studied. Our results provide an enhanced view into the structure and function of the P2 protein from human myelin, which is able to bind both monomeric lipids inside its cavity and membrane surfaces.

Myelin-derived and putative molecular mimic peptides share structural properties in aqueous and membrane-like environments

“…The N terminus of MOBP is predicted to have a membrane-associated FYVE domain [43]. The peripheral myelin protein P2 acts in the formation of myelin membrane stacks, with the two α helices involved in membrane contacts [41,44]. MOG and PLP are transmembrane proteins, in which both the extracellular and cytoplasmic domains may interact with the next apposing lipid bilayer.…”

“…The MOG-derived peptides, as well as the Influenza hemagglutinin peptide (IA mimic), were predicted to harbor β strands, whereas other MBPmimicking peptides (HSV mimic, EB mimic, and PA mimic) as well as the P2-derived peptide P2gbs, contained an α helix as the dominant predicted secondary structure. The latter corresponds to α helix 1 in the crystal structure of human P2 [41,44]. Peptides from PLP were predicted to consist of α-helical parts with a β strand (PLPintra1) or disordered sequences (Table 1), while MOBP15-36 and MOBP37-60 were predicted to have β strand and α helix, respectively, in addition to disordered regions (Table 1).…”

“…The peptide studied here corresponds to the GBS epitope characterized earlier [78], and in the crystal structure, it comprises the first α helix of the lid of the 10-stranded β-barrel structure [44] (Fig. 7a).…”

Interaction of brain fatty acid-binding protein with the polyunsaturated fatty acid environment as a potential determinant of poor prognosis in malignant glioma

“…Fatty acids have also been postulated to enter the brain by passive diffusion and protein-mediated transport by membrane-associated proteins, such as fatty acid transport proteins and fatty acid translocases (CD36) [22]. Inside the cell, long chain fatty acids are transported by a group of intracellular lipid binding proteins called fatty acid binding proteins (FABPs) which are expressed in most tissues [25][26][27][28][29][30][31][32][33][34] (Table 1).…”

DichroCalc: Improvements in Computing Protein Circular Dichroism Spectroscopy in the Near-Ultraviolet

“…Simulations of a phosphate binding protein labeled with two rhodamine fluorophores have been conducted [19], because the protein was not amenable to study by X-ray crystallography or NMR spectroscopy; comparison with experimental biophysical data was facilitated by computing the CD from the MD simulations. A similar approach has been adopted to help design mutants of the coiled-coil domain of the oncoprotein Bcl-Abl [20]; vacuum-UV CD spectrum of human myelin P2 protein has been computed [21] using DichroCalc and qualitatively agreed with experimental measurements made using synchrotron radiation. Simulations and DichroCalc have been used to predict the loss of helicity for peptides binding to the surface of silica [22].…”