Skip to main content
SpringerLink
Log in

How Amphipols Embed Membrane Proteins: Global Solvent Accessibility and Interaction with a Flexible Protein Terminus

  • Published:
The Journal of Membrane Biology Aims and scope Submit manuscript

Abstract

Amphipathic polymers called amphipols provide a valuable alternative to detergents for keeping integral membrane proteins soluble in aqueous buffers. Here, we characterize spatial contacts of amphipol A8-35 with membrane proteins from two architectural classes: The 8-stranded β-barrel outer membrane protein OmpX and the α-helical protein bacteriorhodopsin. OmpX is well structured in A8-35, with its barrel adopting a fold closely similar to that in dihexanoylphosphocholine micelles. The accessibility of A8-35-trapped OmpX by a water-soluble paramagnetic molecule is highly similar to that in detergent micelles and resembles the accessibility in the natural membrane. For the α-helical protein bacteriorhodopsin, previously shown to keep its fold and function in amphipols, NMR data show that the imidazole protons of a polyhistidine tag at the N-terminus of the protein are exchange protected in the presence of detergent and lipid bilayer nanodiscs, but not in amphipols, indicating the absence of an interaction in the latter case. Overall, A8-35 exhibits protein interaction properties somewhat different from detergents and lipid bilayer nanodiscs, while maintaining the structure of solubilized integral membrane proteins.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4

Similar content being viewed by others

Abbreviations

A8-35:

Polyacrylate-based amphipol, carrying ~25 % octylamide chains, ~40 % isopropyl-amide ones, and ~35 % free carboxylates

APol:

Amphipol

BR:

Bacteriorhodopsin

DDM:

n-Dodecyl-β-d-maltopyranoside

DHPC:

1,2-Dihexanoyl-sn-glycero-3-phosphocholine

DMPC:

1,2-Dimyristoyl-sn-glycero-3-phosphocholine

Gd(DOTA)− = DOTAREM:

A gadolinium ion chelated with 1,4,7,10-tetraazocyclododecane-N,N′,N″,N′″-tetraacetic acid

OmpX:

Outer membrane protein X

References

  • Althoff T, Mills DJ, Popot J-L, Kühlbrandt W (2011) Assembly of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1. EMBO J 30:4652–4664

    Article  CAS  Google Scholar 

  • Bayburt TH, Sligar SG (2010) Membrane protein assembly into nanodiscs. FEBS Lett 584:1721–1727

    Article  CAS  Google Scholar 

  • Bayburt TH, Grinkova YV, Sligar SG (2002) Self-assembly of discoidal phospholipid bilayer nanoparticles with membrane scaffold proteins. Nano Lett 2:853–856

    Article  CAS  Google Scholar 

  • Caravan P, Ellison JJ, McMurry TJ, Lauffer RB (1999) Gadolinium(III) chelates as MRI contrast agents: structure, dynamics, and applications. Chem Rev 99:2293–2352

    Article  CAS  Google Scholar 

  • Catoire LJ, Zoonens M, van Heijenoort C, Giusti F, Popot J-L, Guittet E (2009) Inter- and intramolecular contacts in a membrane protein/surfactant complex observed by heteronuclear dipole-to-dipole cross-relaxation. J Magn Res 197:91–95

    Article  CAS  Google Scholar 

  • Catoire LJ, Zoonens M, van Heijenoort C, Giusti F, Guittet E, Popot J-L (2010) Solution NMR mapping of water-accessible residues in the transmembrane β-barrel of OmpX. Eur Biophys J 39:623–630

    Article  CAS  Google Scholar 

  • Champeil P, Menguy T, Tribet C, Popot J-L, le Maire M (2000) Interaction of amphipols with the sarcoplasmic reticulum Ca2+-ATPase. J Biol Chem 275:18623–18637

    Article  CAS  Google Scholar 

  • Dahmane T, Rappaport F, Popot J-L (2013) Amphipol-assisted folding of bacteriorhodopsin in the presence and absence of lipids. Functional consequences. Eur Biophys J 42:85–101

    Article  CAS  Google Scholar 

  • Elter, S, Raschle, T, Arens, S, Gelev, V, Etzkorn, M, Wagner, G (2014). The use of amphipols for NMR structural characterization of 7-TM proteins. (submitted to same issue of J. Membr. Biol.)

  • Etzkorn M, Raschle T, Hagn F, Gelev V, Rice AJ, Walz T, Wagner G (2013) Cell-free expressed bacteriorhodopsin in different soluble membrane mimetics: biophysical properties and NMR accessibility. Structure 21:394–401

    Article  CAS  Google Scholar 

  • Fernández C, Hilty C, Wider G, Guntert P, Wüthrich K (2004) NMR structure of the integral membrane protein OmpX. J Mol Biol 336:1211–1221

    Article  Google Scholar 

  • Gohon Y, Pavlov G, Timmins P, Tribet C, Popot J-L, Ebel C (2004) Partial specific volume and solvent interactions of amphipol A8-35. Anal Biochem 334:318–334

    Article  CAS  Google Scholar 

  • Gohon Y, Giusti F, Prata C, Charvolin D, Timmins P, Ebel C, Tribet C, Popot J-L (2006) Well-defined nanoparticles formed by hydrophobic assembly of a short and polydisperse random terpolymer, amphipol A8-35. Langmuir 22:1281–1290

    Article  CAS  Google Scholar 

  • Gohon Y, Dahmane T, Ruigrok R, Schuck P, Charvolin D, Rappaport F, Timmins P, Engelman DM, Tribet C, Popot J-L, Ebel C (2008) Bacteriorhodopsin/amphipol complexes: structural and functional properties. Biophys J 94:3523–3537

    Article  CAS  Google Scholar 

  • Hilty C, Wider G, Fernández C, Wüthrich K (2004) Membrane protein–lipid interactions in mixed micelles studied by NMR spectroscopy with the use of paramagnetic reagents. ChemBioChem 5:467–473

    Article  CAS  Google Scholar 

  • Huynh, KW, Cohen, MR, Moiseenkova-Bell, VY (2014). Application of amphipols for structure–functional analysis of TRP channels. Submitted for publication to the same issue of J. Membr. Biol

  • Lee D, Hilty C, Wider G, Wüthrich K (2006) Effective rotational correlation times of proteins from NMR relaxation interference. J Magn Reson 178:72–76

    Article  CAS  Google Scholar 

  • Liao M, Cao E, Julius D, Cheng Y (2013) Structure of the TRPV1 ion channel determined by electron cryo-microscopy. Nature 504:107–112

    Article  CAS  Google Scholar 

  • Martinez KL, Gohon Y, Corringer P-J, Tribet C, Mérola F, Changeux J-P, Popot J-L (2002) Allosteric transitions of Torpedo acetylcholine receptor in lipids, detergent and amphipols: molecular interactions vs. physical constraints. FEBS Lett 528:251–256

    Article  CAS  Google Scholar 

  • Pautsch A, Vogt J, Model K, Siebold C, Schulz GE (1999) Strategy for membrane protein crystallization exemplified with OmpA and OmpX. Proteins 34:167–172

    Article  CAS  Google Scholar 

  • Perlmutter, JD, Popot, J-L, Sachs, JN (2014). Molecular dynamics simulations of a membrane protein/amphipol complex. (submitted to same issue of J. Membr. Biol.)

  • Picard M, Dahmane T, Garrigos M, Gauron C, Giusti F, le Maire M, Popot J-L, Champeil P (2006) Protective and inhibitory effects of various types of amphipols on the Ca2+-ATPase from sarcoplasmic reticulum: a comparative study. Biochemistry 45:1861–1869

    Article  CAS  Google Scholar 

  • Planchard, N, Point, E, Dahmane, T, Giusti, F, Renault, M, Le Bon, C, Durand, G, Milon, A, Guittet, E, Zoonens, M, Popot, J-L, Catoire, LJ (2014). The use of amphipols for solution NMR studies of membrane proteins: advantages and limitations as compared to other solubilizing media. (submitted to same issue of J. Membr. Biol.)

  • Plesniak LA, Mahalakshmi R, Rypien C, Yang Y, Racic J, Marassi FM (2011) Expression, refolding, and initial structural characterization of the Y. pestis Ail outer membrane protein in lipids. Biochim Biophys Acta 1808:482–489

    Article  CAS  Google Scholar 

  • Popot J-L (2010) Amphipols, nanodiscs, and fluorinated surfactants: three non-conventional approaches to studying membrane proteins in aqueous solutions. Annu Rev Biochem 79:737–775

    Article  CAS  Google Scholar 

  • Popot J-L, Althoff T, Bagnard D, Banères J-L, Bazzacco P, Billon-Denis E, Catoire LJ, Champeil P, Charvolin D, Cocco MJ, Crémel G, Dahmane T, de la Maza LM, Ebel C, Gabel F, Giusti F, Gohon Y, Goormaghtigh E, Guittet E, Kleinschmidt JH, Kühlbrandt W, Le Bon C, Martinez KL, Picard M, Pucci B, Rappaport F, Sachs JN, Tribet C, van Heijenoort C, Wien F, Zito F, Zoonens M (2011) Amphipols from A to Z. Annu Rev Biophys 40:379–408

    Article  CAS  Google Scholar 

  • Raschle T, Hiller S, Etzkorn M, Wagner G (2010) Nonmicellar systems for solution NMR spectroscopy of membrane proteins. Curr Opin Struct Biol 20:471–479

    Article  CAS  Google Scholar 

  • Tribet C, Audebert R, Popot J-L (1996) Amphipols: polymers that keep membrane proteins soluble in aqueous solutions. Proc Natl Acad Sci USA 93:15047–15050

    Article  CAS  Google Scholar 

  • Vogt J, Schulz GE (1999) The structure of the outer membrane protein OmpX from Escherichia coli reveals possible mechanisms of virulence. Structure 7:1301–1309

    Article  CAS  Google Scholar 

  • Zhou HX, Cross TA (2013) Influences of membrane mimetic environments on membrane protein structures. Annu Rev Biophys 42:361–392

    Article  CAS  Google Scholar 

  • Zoonens M, Popot J-L (2014). Amphipols for each season. (to be submitted to same issue of J. Membr. Biol.)

  • Zoonens M, Catoire LJ, Giusti F, Popot J-L (2005) NMR study of a membrane protein in detergent-free aqueous solution. Proc Natl Acad Sci USA 102:8893–8898

    Article  CAS  Google Scholar 

Download references

Acknowledgments

We thank Profs. Kurt Wüthrich and Gerhard Wagner for their kind support of materials and instrument time, Prof. Gerhard Wider for helpful discussions and F. Giusti (UMR 7099) for the synthesis of deuterated A8-35. This work was supported by grants from the German Academic Exchange Service (DAAD) and the DFG (ET 103/2-1) to M.E., as well as the Swiss National Science Foundation (Grant PP00P3_128419) and the European Research Council (FP7 contract MOMP 281764) to S.H., by the French Centre National de la Recherche Scientifique, Université Paris-7, and grants from the CNRS interdisciplinary program Physique et Chimie du Vivant, from the EU (BIO4-CT98-0269), from the Human Frontier Science Program Organization (Grant RG00223/2000-M), and from E.U. Specific Targeted Research Project IMPS (Innovative tools for membrane protein structural proteomics) to J.L.P.

Author information

Authors and Affiliations

  1. Institute of Physical Biology, Heinrich Heine University, Universitätsstr. 1, 40225, Düsseldorf, Germany

    Manuel Etzkorn

  2. UMR 7099, Institut de BiologiePhysico-Chimique, CNRS/Université Paris-7, FRC 550, 13 rue Pierre et Marie Curie, 75005, Paris, France

    Manuela Zoonens, Laurent J. Catoire & Jean-Luc Popot

  3. Biozentrum, University of Basel, Klingelbergstr. 70, 4056, Basel, Switzerland

    Sebastian Hiller

Authors
  1. Manuel Etzkorn
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Manuela Zoonens
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Laurent J. Catoire
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jean-Luc Popot
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Sebastian Hiller
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Sebastian Hiller.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Etzkorn, M., Zoonens, M., Catoire, L.J. et al. How Amphipols Embed Membrane Proteins: Global Solvent Accessibility and Interaction with a Flexible Protein Terminus. J Membrane Biol 247, 965–970 (2014). https://doi.org/10.1007/s00232-014-9657-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00232-014-9657-9

Keywords

Search

Navigation