NR AWBZ
AU Bera,A.; Roche,A.C.; Nandi,P.K.
TI Prion protein induces sequence dependent condensation of nucleic acids
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions S-02
PT Konferenz-Poster
AB We found earlier that prion protein accelerates hybridization of complementary DNA strands by biochemical methods and induces a time-dependent change in the nucleic acid morphology leading to the ordered aggregation of condensed DNA molecules which appeared as globules by ultra structural studies. The prion protein-induced ordered nucleic acid globules are different from other known morphologically altered nucleic acid structures induced by other DNA-binding cellular proteins. We report here the initial step of DNA condensation in the presence of prion protein by biophysical methods by using the fluorescence properties of an oxazole yellow dye, YOYO, intercalated in DNA. The protein induces fluorescence quenching of the dye which is greater with DNA containing only GC bases compared to the DNA containing equimolar concentrations of four bases. Interestingly, the prion protein is without any significant effect on the fluorescence properties of the dye intercalated in DNA containing only AT bases. Biological polyamines which condenses DNA are less effective than prion protein in quenching of YOYO fluorescence bound to DNA. Prion protein induces only marginal quenching of fluorescence of the dye bound to oligonucleotides which are generally resistant to condensation. Studies also show that interaction of the protein with DNA induces greater exposure of the bases to the bulk solvent with DNA containing GC bases compared to the one containing four nucleic acid bases. This probably can explain the increased association and condensation of the GC DNA in the presence of the prion protein. The increased base exposure and condensation of GC-rich DNA by prion protein may suggest a biological function of the prion protein and a role in its pathogenesis.
AD A. Bera, P.K. Nandi: Infectiologie Animale et Santé Publique, Institut National de la Recherche Agronomique, 37380 Nouzilly, France; A.-C. Roche: Glycobiologie, Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique, 45071 Orléans Cedex, France. E-mail: nandi@tours.inra.fr
SP englisch
PO Italien