In vitro prion protein conversion in detergent-solubilized membranes

Area of Science:

• Neuroscience
• Biochemistry
• Molecular Biology

Background:

• Prion diseases are linked to the misfolding of cellular prion protein (PrP(C)) into infectious PrP(Sc).
• Protein Misfolding Cyclic Amplification (PMCA) is an in vitro method to amplify PrP(Sc)-like molecules (PrPres).
• Understanding the requirements for PrP(C) conversion is crucial for modeling prion pathogenesis.

Purpose of the Study:

• To investigate whether membrane association is necessary for PrP(C) conversion into PrPres in vitro.
• To determine if detergent-solubilized membrane preparations can support PrPres amplification.
• To assess the feasibility of purifying factors involved in prion conversion.

Main Methods:

• Utilized a modified Protein Misfolding Cyclic Amplification (PMCA) technique.
• Employed membrane fractionation to isolate synaptic plasma membrane preparations enriched in PrP(C).
• Performed detergent solubilization experiments on membrane preparations.

Main Results:

• Purified synaptic plasma membranes, depleted of endosomal/lysosomal markers, supported PrPres amplification.
• Specific detergents allowed for the creation of soluble PrP(C) preparations that fully supported PrPres amplification.
• The ability of detergent-solubilized preparations to amplify PrPres was dependent on detergent concentration.

Conclusions:

• Membrane attachment is not essential for efficient in vitro conversion of PrP(C) to PrPres.
• Detergent-solubilized membrane preparations containing PrP(C) can serve as a model for prion conversion.
• These findings suggest that biochemical purification of prion conversion factors from brain homogenates is a viable strategy.