Bending and unwinding of nucleic acid by prion protein

A. Bera, A. C. Roche, P. K. Nandi

Research output: Contribution to journalArticle

Abstract

Nucleic acid induces conformational changes in the prion protein (23-231 amino acids) to a structure resembling its pathological isoform. The prion protein, in turn, facilitates DNA strand transfer and acts as a DNA chaperone which is modulated by the N-terminal unstructured basic segment of the protein. Here we have studied the prion protein induced conformational changes in DNA using oligonucleotides covalently labeled with the energy donor fluorescein and the acceptor rhodamine moieties by fluorescence resonance energy transfer (FRET) and by thermal stability of the unlabeled oligonucleotides. The protein induces a strong FRET effect in the oligonucleotides evidenced from the simultaneous quenching of fluorescence intensity of the donor and increase in the fluorescence intensity of the acceptor, which indicate bending of the oligonucleotides by the prion protein. The energy transfer efficiency induced by the protein is greater for the larger oligonucleotide. The prion protein also induces significant structural destabilization of the oligonucleotides observed from the lowering of their melting temperatures in the presence of the protein. The truncated globular prion protein 121-231 fragment neither induces FRET effect on the oligonucleotides nor destabilizes their structures, indicating that the N-terminal segment of the prion protein is essential for the DNA bending process. Equilibrium binding and kinetics of FRET show that the protein binding to the oligonucleotides and their bending occur simultaneously. The DNA structural changes observed in the presence of the prion protein are similar to those caused by proteins involved in initiation and regulation for protein synthesis.

Original languageEnglish (US)
Pages (from-to)1320-1328
Number of pages9
JournalBiochemistry®
Volume46
Issue number5
DOIs
StatePublished - Feb 6 2007
Externally publishedYes

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Oligonucleotides
Nucleic Acids
Fluorescence Resonance Energy Transfer
DNA
Proteins
Fluorescence
Rhodamines
Prion Proteins
Prions
Energy Transfer
Fluorescein
Protein Binding
Energy transfer
Freezing
Melting point
Quenching
Protein Isoforms
Thermodynamic stability
Hot Temperature
Amino Acids

ASJC Scopus subject areas

  • Biochemistry

Cite this

Bera, A., Roche, A. C., & Nandi, P. K. (2007). Bending and unwinding of nucleic acid by prion protein. Biochemistry®, 46(5), 1320-1328. https://doi.org/10.1021/bi0620050

Bending and unwinding of nucleic acid by prion protein. / Bera, A.; Roche, A. C.; Nandi, P. K.

In: Biochemistry®, Vol. 46, No. 5, 06.02.2007, p. 1320-1328.

Research output: Contribution to journalArticle

Bera, A, Roche, AC & Nandi, PK 2007, 'Bending and unwinding of nucleic acid by prion protein', Biochemistry®, vol. 46, no. 5, pp. 1320-1328. https://doi.org/10.1021/bi0620050
Bera, A. ; Roche, A. C. ; Nandi, P. K. / Bending and unwinding of nucleic acid by prion protein. In: Biochemistry®. 2007 ; Vol. 46, No. 5. pp. 1320-1328.
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