PMID: 24419389

Authors:

Ruskamo S, Yadav RP, Sharma S, Lehtimaki M, Laulumaa S, Aggarwal S, Simons M, Burck J, Ulrich AS, Juffer AH, Kursula I, Kursula P

Title:

Atomic resolution view into the structure-function relationships of the human myelin peripheral membrane protein P2.

Journal:

Acta Crystallogr D Biol Crystallogr. 2014 Jan;70(Pt 1):165-76. doi:, 10.1107/S1399004713027910. Epub 2013 Dec 31.

Abstract:

P2 is a fatty acid-binding protein expressed in vertebrate peripheral nerve myelin, where it may function in bilayer stacking and lipid transport. P2 binds to phospholipid membranes through its positively charged surface and a hydrophobic tip, and accommodates fatty acids inside its barrel structure. The structure of human P2 refined at the ultrahigh resolution of 0.93 A allows detailed structural analyses, including the full organization of an internal hydrogen-bonding network. The orientation of the bound fatty-acid carboxyl group is linked to the protonation states of two coordinating arginine residues. An anion-binding site in the portal region is suggested to be relevant for membrane interactions and conformational changes. When bound to membrane multilayers, P2 has a preferred orientation and is stabilized, and the repeat distance indicates a single layer of P2 between membranes. Simulations show the formation of a double bilayer in the presence of P2, and in cultured cells wild-type P2 induces membrane-domain formation. Here, the most accurate structural and functional view to date on P2, a major component of peripheral nerve myelin, is presented, showing how it can interact with two membranes simultaneously while going through conformational changes at its portal region enabling ligand transfer.