Self-assembling peptides form nanodiscs that stabilize membrane proteins

Abstract

New methods to handle membrane bound proteins, e.g. G-protein coupled receptors (GPCRs), are highly desirable. Recently, apoliprotein A1 (ApoA1) based lipoprotein particles have emerged as a new platform for studying membrane proteins, and it has been shown that they can self-assemble in combination with phospholipids to form discoidal shaped particles that can stabilize membrane proteins. In the present study, we have investigated an ApoA1 mimetic peptide with respect to its solution structure when in complex with phospholipids. This was achieved using a powerful combination of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) supported by coarse-grained molecular dynamics simulations. The detailed structure of the discs was determined in unprecedented detail and it was found that they adopt a discoidal structure very similar to the ApoA1 based nanodiscs. We furthermore show that, like the ApoA1 and derived nanodiscs, these peptide discs can accommodate and stabilize a membrane protein. Finally, we exploit their dynamic properties and show that the 18A discs may be used for transferring membrane proteins and associated phospholipids directly and gently into phospholipid nanodiscs.

Self-assembled peptide-based nanostructures: Smart nanomaterials toward targeted drug delivery

“…ApoA1 is the main constituent in high-density lipoproteins (HDLs) and is known to form discoidal particles when associated with lipids. Midtgaard et al examined an ApoA1 mimetic peptide referred to as A18, and its solution structure [86]. A18 is an 18-amino-acid amphipathic a-helical peptide of class A, assembled synthetically into bicelles to mimic the in vivo properties of ApoA1 (Fig.…”

Small-Angle X-Ray Scattering of the Cholesterol Incorporation into Human ApoA1-POPC Discoidal Particles

“…This has sparked new structural methods and better data analysis procedures, allowing for a much more detailed structural description of the different variants of ApoA1 (3,14) and similar systems (15).…”

Biomembranes research using thermal and cold neutrons

“…In its simplest use, SANS can determine the low resolution structure and conformation of detergent solubilized membrane proteins in solution, or more elegantly, to investigate protein structure, oligomerization and interactions when reconstituted into lipid carriers and biomimetic assemblies such as bicelles and nanodiscs (Midtgaard, Pedersen et al 2014). Careful contrast matching then allows scattering from the protein and surrounding detergent or lipid molecules to be measured and distinguished, and for composite models of the protein, lipid and/or detergent components to be determined.…”