A quantitative characterization of interaction between prion protein with nucleic acids

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Prion proteins are implicated in neurodegenerative diseases.
• The role of nucleic acids in prion protein interactions and potential conversion to infectious forms remains an area of investigation.

Purpose of the Study:

• To investigate the binding interactions between recombinant prion protein and various structured RNAs.
• To elucidate the influence of RNA composition, structure, and solution pH on these binding dynamics.

Main Methods:

• Studied prion protein-RNA binding using fluorescence anisotropy of intrinsic tryptophan residues.
• Analyzed changes in fluorescence anisotropy to determine binding affinities and site numbers.
• Investigated binding parameters across different pH conditions and RNA types.

Main Results:

• Prion protein exhibited comparable binding affinities and site numbers for diverse RNAs (mRNA pseudoknots, tRNA, polyA).
• Binding parameters were largely independent of RNA composition and structure, but pH-dependent.
• At pH 5, larger nucleoprotein complexes formed, driven by nonpolar group interactions, contrasting with electrostatic dominance at neutral pH.
• Species-specific interactions were observed between prion protein and its cognate mRNA pseudoknots, suggesting structural recognition.

Conclusions:

• Prion protein-RNA interactions are robust across different nucleic acid types, primarily dictated by RNA structure rather than sequence.
• pH significantly modulates the binding mechanism, shifting from electrostatic to nonpolar interactions.
• These findings offer insights into potential roles of nucleic acids in prion protein function and pathogenesis.