University of Oulu

Salla Ruskamo, Oda C. Krokengen, Julia Kowal, Tuomo Nieminen, Mari Lehtimäki, Arne Raasakka, Venkata P. Dandey, Ilpo Vattulainen, Henning Stahlberg, Petri Kursula, Cryo-EM, X-ray diffraction, and atomistic simulations reveal determinants for the formation of a supramolecular myelin-like proteolipid lattice, Journal of Biological Chemistry, Volume 295, Issue 26, 2020, Pages 8692-8705, ISSN 0021-9258,

Cryo-EM, X-ray diffraction, and atomistic simulations reveal determinants for the formation of a supramolecular myelin-like proteolipid lattice

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Author: Ruskamo, Salla1,2; Krokengen, Oda C.3; Kowal, Julia4;
Organizations: 1Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
2Biocenter Oulu, University of Oulu, 90014 Oulu, Finland
3Department of Biomedicine, University of Bergen, 5020 Bergen, Norway
4Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, 4058 Basel, Switzerland
5Computational Physics Laboratory, Tampere University, 33014 Tampere, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: American Society for Biochemistry and Molecular Biology, 2020
Publish Date: 2021-03-05


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.

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Series: Journal of biological chemistry
ISSN: 0021-9258
ISSN-E: 1083-351X
ISSN-L: 0021-9258
Volume: 295
Issue: 26
Pages: 8692 - 8705
DOI: 10.1074/jbc.RA120.013087
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: Beamtime and user support at EMBL/DESY and ISA are gratefully acknowledged. Travel to synchrotrons was supported by the Norwegian Research Council (SYNKNØYT Project 247669) and the European Union Horizon 2020 programs iNEXT (Grant 653706) and CALIPSOplus (Grant 730872).
EU Grant Number: (653706) iNEXT - Infrastructure for NMR, EM and X-rays for translational research
Copyright information: © 2020 Ruskamo et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology. This is an Open Access article under the CC BY license.