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Interaction of prion peptide HuPrP106-126 with nucleic acid
1Institut National de la Recherche Agronomique, Pathologie Infectieuse et Immunologie, Nouzilly, France.
Abstract:
Synthetic prion peptide PrP106-126 has been used as a model to understand prion diseases. The conformation of the peptide depends on the environmental conditions and it forms amyloid in vitro. The potential of this prion peptide to interact with nucleic acids has been studied using a fluorescent labelled nucleic acid by kinetic and equilibrium methods. A decrease in the fluorescence of the labelled DNA induced by the peptide with time is observed which is pH, ionic strength and temperature dependent. The activation energy of the reactions is approximately 100 kJ mol-1. Lysine tripeptide and spermidine, carrying the same number of positive charges as the prion peptide, do not show an appreciable effect on the DNA. The binding constant between the prion peptide and DNA has a value of > 10(6) M-1 in phosphate buffer, pH 8 which is of the same order of magnitude as the binding of a retroviral protein, p10, with model nucleic acids. It is tempting to speculate that this interaction might play a role in the prion diseases.
Insights
Synthetic prion peptide PrP106-126 interacts with DNA, forming amyloid structures relevant to prion diseases. This peptide-nucleic acid interaction is pH, ionic strength, and temperature-dependent, with a high binding affinity.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Prion diseases are linked to misfolded prion proteins.
- Synthetic prion peptide PrP106-126 serves as a model for studying these diseases.
- PrP106-126 can form amyloid structures influenced by environmental conditions.
Purpose of the Study:
- To investigate the interaction between the synthetic prion peptide PrP106-126 and nucleic acids.
- To characterize the binding kinetics and thermodynamics of this interaction.
- To explore the potential role of this interaction in prion disease pathogenesis.
Main Methods:
- Utilized a fluorescently labeled nucleic acid to study peptide-nucleic acid interactions.
- Employed kinetic and equilibrium methods to analyze binding.
- Investigated the influence of pH, ionic strength, and temperature on the interaction.
Main Results:
- Observed a time-dependent decrease in nucleic acid fluorescence upon addition of PrP106-126.
- The interaction is sensitive to pH, ionic strength, and temperature, with an activation energy of approximately 100 kJ mol-1.
- PrP106-126 exhibited a high binding constant (> 10^6 M-1) with DNA, comparable to retroviral protein p10.
- Control peptides (lysine tripeptide, spermidine) did not show significant effects on DNA.
Conclusions:
- The synthetic prion peptide PrP106-126 binds strongly to nucleic acids.
- This interaction is influenced by environmental factors and shows high affinity.
- The findings suggest a potential role for peptide-nucleic acid interactions in the mechanisms underlying prion diseases.