Professor
Biochemistry and Molecular Biology
Faculty of Medicine
University of Marseilles, France, 1990, BSc
University of Marseilles, France, 1994, PhD
Dartmouth Medical School, USA, 1998, Postdoctoral Fellow
CNRS-University of Paris-Sud, France, 2004,
Principle Investigator
phone: 6048225975
phone: 6048225245
Life Sciences Centre, Office 5407
2350 Health Sciences Mall
Vancouver, BC V6T 1Z3
Canada

Investigating Membrane Protein Structure, Function and Interactions using the Peptidisc

Membrane proteins represent ~60% of medical drug targets and encompass 1/5th of the human proteome; yet these proteins are vastly under-represented in structure and interaction databases. This discrepancy is due to biochemical and biophysical studies requiring proteins in a water-soluble state, while membrane proteins are naturally sequestered in a hydrophobic lipid environment. In order to render membrane proteins into a soluble state, that is amenable for their study, researchers generally use detergents to extract and purify these proteins. However, these surfactants have many undesired effects on protein structure, function and downstream analysis.   Work from our group and others has focused on developing nanotechnology-based reconstitution systems to try replacing the natural lipid bilayer while maintaining water-solubility. These membrane mimetics, either protein-based scaffolds or synthetic polymers, have been around for a decade, yet their utilities did not reach the expected potential due to the optimization and adaptation required for each membrane protein system. Recently, our laboratory developed a “one-size-fits-all” formulation known as the Peptidisc— the Peptidisc is made by multiple copies of an amphipathic peptide that spontaneously associate around transmembrane domains of proteins upon removal of detergent. The peptide number adapts spontaneously to fit the size and shape of the protein, allowing for minimal reconstitution optimization.   The end result is a membrane protein that is stable, free of detergent effects, and soluble in aqueous solution. The Peptidisc is a new tool that we hope will allow more researchers, including those who are not expert biochemists, to study membrane proteins. This will yield a better understanding of the structure and function of the cellular membrane as it interacts with the environment. Since the approach is both simple and easy to apply, more membrane proteins may now be included in high-throughput searches for potential new drugs that may help treat various medical conditions.

Dalal, K., Chan, C.S., Sligar, S.G., and Duong, F. (2012) Two copies of the SecY channel are necessary to activate the SecA translocation ATPase. Submitted.

Zhang, X.X., Chan, C.S., Bao, H., Fang, Y., Foster, L.J., and Duong, F. (2011). Nanodiscs and SILAC-Based Mass Spectrometry to Identify a Membrane Protein Interactome. J. Proteome Res. In press.

Dalal, K., and Duong, F. (2011). The SecY complex: conducting the orchestra of protein translocation. Trends Cell Biol. 9, 506-514.

Dalal, K., Bao, H., and Duong, F. (2010). Modulation of the SecY channel permeability by pore mutations and trivalent cations. Channels (Austin) 2, 83-86.

Dalal, K., and Duong, F. (2010). Reconstitution of the SecY translocon in nanodiscs. Methods Mol. Biol. 145-156.

Gold, V.A., Robson, A., Bao, H., Romantsov, T., Duong, F., and Collinson, I. (2010). The action of cardiolipin on the bacterial translocon. Proc. Natl. Acad. Sci. U. S. A. 22, 10044-10049.

Dalal, K., and Duong, F. (2009). The SecY complex forms a channel capable of ionic discrimination. EMBO Rep. 7, 762-768.

Dalal, K., Nguyen, N., Alami, M., Tan, J., Moraes, T.F., Lee, W.C., Maurus, R., Sligar, S.S., Brayer, G.D., and Duong, F. (2009). Structure, binding, and activity of Syd, a SecY-interacting protein. J. Biol. Chem. 12, 7897-7902.

Duong, F. (2007). Cell biology: fraternal twins. Nature 7137, 741-743.

Alami, M., Dalal, K., Lelj-Garolla, B., Sligar, S.G., and Duong, F. (2007). Nanodiscs unravel the interaction between the SecYEG channel and its cytosolic partner SecA. EMBO J. 8, 1995-2004.

Maillard, A.P., Lalani, S., Silva, F., Belin, D., and Duong, F. (2007). Deregulation of the SecYEG translocation channel upon removal of the plug domain. J. Biol. Chem. 2, 1281-1287.

Gold, V.A., Duong, F., and Collinson, I. (2007). Structure and function of the bacterial Sec translocon. Mol. Membr. Biol. 5-6, 387-394.

Tam, P.C., Maillard, A.P., Chan, K.K., and Duong, F. (2005). Investigating the SecY plug movement at the SecYEG translocation channel. EMBO J. 19, 3380-3388.

Tziatzios, C., Schubert, D., Lotz, M., Gundogan, D., Betz, H., Schagger, H., Haase, W., Duong, F., and Collinson, I. (2004). The bacterial protein-translocation complex: SecYEG dimers associate with one or two SecA molecules. J. Mol. Biol. 3, 513-524.

Eichler, J., and Duong, F. (2004). Break on through to the other side–the Sec translocon. Trends Biochem. Sci. 5, 221-223.

Duong, F. (2003). Binding, activation and dissociation of the dimeric SecA ATPase at the dimeric SecYEG translocase. EMBO J. 17, 4375-4384.

Bessonneau, P., Besson, V., Collinson, I., and Duong, F. (2002). The SecYEG preprotein translocation channel is a conformationally dynamic and dimeric structure. EMBO J. 5, 995-1003.

Collinson, I., Breyton, C., Duong, F., Tziatzios, C., Schubert, D., Or, E., Rapoport, T., and Kuhlbrandt, W. (2001). Projection structure and oligomeric properties of a bacterial core protein translocase. EMBO J. 10, 2462-2471.

Duong, F., Bonnet, E., Geli, V., Lazdunski, A., Murgier, M., and Filloux, A. (2001). The AprX protein of Pseudomonas aeruginosa: a new substrate for the Apr type I secretion system. Gene 1-2, 147-153.

Duong, F., and Wickner, W. (1999). The PrlA and PrlG phenotypes are caused by a loosened association among the translocase SecYEG subunits. EMBO J. 12, 3263-3270.

Duong, F., and Wickner, W. (1998). Sec-dependent membrane protein biogenesis: SecYEG, preprotein hydrophobicity and translocation kinetics control the stop-transfer function. EMBO J. 3, 696-705.

Duong, F., Eichler, J., Price, A., Leonard, M.R., and Wickner, W. (1997). Biogenesis of the gram-negative bacterial envelope. Cell 5, 567-573.

Duong, F., and Wickner, W. (1997). Distinct catalytic roles of the SecYE, SecG and SecDFyajC subunits of preprotein translocase holoenzyme. EMBO J. 10, 2756-2768.

Duong, F., and Wickner, W. (1997). The SecDFyajC domain of preprotein translocase controls preprotein movement by regulating SecA membrane cycling. EMBO J. 16, 4871-4879.

Price, A., Economou, A., Duong, F., and Wickner, W. (1996). Separable ATPase and membrane insertion domains of the SecA subunit of preprotein translocase. J. Biol. Chem. 49, 31580-31584.

Duong, F., Lazdunski, A., and Murgier, M. (1996). Protein secretion by heterologous bacterial ABC-transporters: the C-terminus secretion signal of the secreted protein confers high recognition specificity. Mol. Microbiol. 3, 459-470.

Duong, F., Soscia, C., Lazdunski, A., and Murgier, M. (1994). The Pseudomonas fluorescens lipase has a C-terminal secretion signal and is secreted by a three-component bacterial ABC-exporter system. Mol. Microbiol. 6, 1117-1126.