Cryo-EM, X-ray diffraction, and atomistic simulations reveal determinants for the formation of a supramolecular myelin-like proteolipid lattice
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Details
| Original language | English |
|---|---|
| Pages (from-to) | 8692-8705 |
| Number of pages | 14 |
| Journal | The Journal of biological chemistry |
| Volume | 295 |
| Issue number | 26 |
| DOIs | |
| Publication status | Published - 26 Jun 2020 |
| Publication type | A1 Journal article-refereed |
Abstract
Myelin protein P2 is a peripheral membrane protein of the fatty acid-binding protein family that functions in the formation and maintenance of the peripheral nerve myelin sheath. Several P2 gene mutations cause human Charcot-Marie-Tooth neuropathy, but the mature myelin sheath assembly mechanism is unclear. Here, cryo-EM of myelin-like proteolipid multilayers revealed an ordered three-dimensional (3D) lattice of P2 molecules between stacked lipid bilayers, visualizing supramolecular assembly at the myelin major dense line. The data disclosed that a single P2 layer is inserted between two bilayers in a tight intermembrane space of ∼3 nm, implying direct interactions between P2 and two membrane surfaces. X-ray diffraction from P2-stacked bicelle multilayers revealed lateral protein organization, and surface mutagenesis of P2 coupled with structure-function experiments revealed a role for both the portal region of P2 and its opposite face in membrane interactions. Atomistic molecular dynamics simulations of P2 on model membrane surfaces suggested that Arg-88 is critical for P2-membrane interactions, in addition to the helical lid domain. Negatively charged lipid headgroups stably anchored P2 on the myelin-like bilayer surface. Membrane binding may be accompanied by opening of the P2 β-barrel structure and ligand exchange with the apposing bilayer. Our results provide an unprecedented view into an ordered, multilayered biomolecular membrane system induced by the presence of a peripheral membrane protein from human myelin. This is an important step toward deciphering the 3D assembly of a mature myelin sheath at the molecular level.
ASJC Scopus subject areas
Keywords
- Charcot-Marie-Tooth disease, membrane bilayer, membrane biophysics, membrane protein, membrane structure, molecular dynamics, myelin, neuropathy, protein structure, proteolipid