Meine neue Veröffentlichung „Cell-free synthesis of membrane proteins: Tailored cell models out of microsomes“

Meine neue Veröffentlichung „Cell-free synthesis of membrane proteins: Tailored cell models out of microsomes“
9. Dezember 2013 Rita

My first publication: “Synthesis of membrane proteins in eukaryotic cell-free systems”. It is all about membrane protein synthesis in eukaryotic Spodoptera frugiperda based cell-free systems, posttranslational modification and fluorescence labelling with non-canonical amino acids.

If you don’t know what that means, it is one more reason to read it!

Highlights

  • Cell-free expression of various membrane proteins into endogenous microsomes
  • Electroswelling of hybrid-GUVs from microsomes in the presence of synthetic lipids
  • Synthetic lipids accelerate the electroswelling process.
  • Single-molecule microscopy of hybrid-GUVs indicates the dimerization of GPCRs.
  • Presentation of advanced cell models to study transmembrane proteins in situ

Abstract

Incorporation of proteins in biomimetic giant unilamellar vesicles (GUVs) is one of the hallmarks towards cell models in which we strive to obtain a better mechanistic understanding of the manifold cellular processes. The reconstruction of transmembrane proteins, like receptors or channels, into GUVs is a special challenge. This procedure is essential to make these proteins accessible to further functional investigation. Here we describe a strategy combining two approaches: cell-free eukaryotic protein expression for protein integration and GUV formation to prepare biomimetic cell models. The cell-free protein expression system in this study is based on insect lysates, which provide endoplasmic reticulum derived vesicles named microsomes. It enables signal-induced translocation and posttranslational modification of de novo synthesized membrane proteins. Combining these microsomes with synthetic lipids within the electroswelling process allowed for the rapid generation of giant proteo-liposomes of up to 50 μm in diameter. We incorporated various fluorescent protein-labeled membrane proteins into GUVs (the prenylated membrane anchor CAAX, the heparin-binding epithelial growth factor like factor Hb-EGF, the endothelin receptor ETB, the chemokine receptor CXCR4) and thus presented insect microsomes as functional modules for proteo-GUV formation. Single-molecule fluorescence microscopy was applied to detect and further characterize the proteins in the GUV membrane. To extend the options in the tailoring cell models toolbox, we synthesized two different membrane proteins sequentially in the same microsome. Additionally, we introduced biotinylated lipids to specifically immobilize proteo-GUVs on streptavidin-coated surfaces. We envision this achievement as an important first step toward systematic protein studies on technical surfaces.

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