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Semisynthesis of membrane-attached prion proteins
Nam Ky Chu1, Christian F W Becker
1Technische Universität München, Department of Chemistry, Protein Chemistry Group, Garching, Germany.
Methods in Enzymology
|July 28, 2009
Summary
Researchers developed protein semisynthesis to create membrane-attached prion protein (PrP) variants. This method yields sufficient quantities for studying PrP
Area of Science:
- Biochemistry
- Neuroscience
- Molecular Biology
Background:
- Prion diseases involve the conversion of cellular prion protein (PrP(C)) to a pathological form (PrP(Sc)).
- Studying membrane-associated PrP and its behavior is challenging due to difficulties in expressing and purifying modified variants.
- Recombinantly expressed PrP (rPrP) has been used, but post-translationally modified forms are limited.
Purpose of the Study:
- To develop a method for producing milligram quantities of membrane-attached recombinant PrP (rPrP) variants.
- To investigate the properties and behavior of these modified PrP variants in vitro and in vivo.
- To overcome challenges in studying lipidated PrP, crucial for understanding prion disease mechanisms.
Main Methods:
- Protein semisynthesis using E. coli expression of rPrP fused to inteins (Mycobacterium xenopi GyrA or Synechocystis sp. DnaE).
- Chemical synthesis of palmitoylated membrane anchor peptides (for rPrP(Palm)) or glycosylphosphatidylinositol (GPI) anchors (for rPrP(GPI)).
- Overcoming solubility issues with polyethylene glycol tags or liposome incorporation.
Main Results:
- Successfully produced rPrP(Palm) and rPrP(GPI) variants with membrane anchors.
- rPrP(Palm) showed high liposome affinity and an increased aggregation lag phase compared to standard rPrP.
- rPrP(GPI) demonstrated efficient membrane attachment with a single alkyl chain.
- In vivo studies confirmed efficient uptake of double-lipidated rPrP(Palm) into neuronal and kidney cell membranes.
Conclusions:
- Protein semisynthesis is an effective strategy for generating substantial amounts of membrane-associated PrP variants.
- Lipidated PrP variants exhibit altered biophysical properties, including enhanced membrane interaction and modified aggregation kinetics.
- These findings provide valuable tools for in-depth investigation of prion protein's role in disease pathogenesis.
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