NR AXVS
AU Sakasegawa,Y.; Hachiya,N.S.; Kaneko,K.; Doh-ura,K.
TI HSP90 Family Proteins Modify the Comformation of Copper-Loaded Prion Protein in a Nucleotide-Dependent Manner
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Protein Misfolding P01.09
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB The quality control system prevents proteins from misfolding/aggregating states, and its dysfunction is apparently involved in the development of prion diseases. The causative agent of prion diseases is suggested to be a disease isoform of prion protein (PrPsc), which is produced by a conformational change of a cellular prion protein (PrPc), but the mechanism of this process is yet unknown. To find cellular components modifying the conformation of PrPc, we constructed an assay system using a-helixrich, 3F4-tagged recombinant prion protein (rPrP) as a substrate. This assay system is composed of two reactions; 1) denaturation of the rPrP with candidate subcellular fractions, 2) subsequent digestion with a low concentration of trypsin which can degrade trypsin-sensitive sites of the rPrP. Consequently, we purified the activity by three chromatography steps and identified it as heat shock protein 90 (Hsp90) by TOF/MS/MS. Hsp90 is a 90-kDa chaperone protein abundantly expressed in the cytosolic and nuclear compartments. In the in vitro assay, no nucleotides such as ATP were necessary for Hsp90-assisted conformational modification of the rPrP. In the presence of 0.1 mM copper, however, rPrP was converted into a conformation that was more resistant to the trypsin digestion, of which the Hsp90-assisted conformational modification required ATP or ADP, but not AMP. Nonhydrolyzable ATP analogues, ATP-gS and AMP-PNP also enabled Hsp90 to modify the conformation of copper-loaded rPrP, suggesting that the hydrolysis of ATP is not required for the reaction in the presence of copper. In addition, Grp94, an endoplasmic-resident homologue of Hsp90, also modified the conformation of the copper-loaded rPrP in the presence of ATP or ADP. These results suggest that Hsp90 family proteins may be related to the conformational modification of copper-loaded PrPc in a nucleotidedependent manner.
AD Y. Sakasegawa, K. Doh-ura, Tohoku University Graduate School of Medicine, Department of Prion Research, Japan; N.S. Hachiya, K. Kaneko, Tokyo Medical University, Department of Neurophysiology, Japan
SP englisch
PO Schottland