NR ARDW
AU Leliveld,S.R.; Klingenstein,R.; Lingappa,V.R.; Korth,C.
TI Copper-dependent interactions of the prion protein
QU TSE-Forum, 4. Kongress - Nationale TSE-Forschungsplattform, Düsseldorf 28.10.-29.10.2004, Poster GL-05
PT Konferenz-Poster
AB
Although the biological role of the normal prion protein (PrPc) is currently unknown, copper binding by the highly conserved N-terminal octarepeat (OR) or (PHGGGWGQ)4 domain is likely to be of importance in PrP's physiological function. Insertion of up to nine additional octarepeats into the human PrP gene has been genetically linked to familial Creutzfeldt Jakob disease. Here, we present our findings on the effect of copper-dependent interactions of PrP with itself and with other proteins.
As a ligand for the octarepeat region, we have isolated a monoclonal antibody (mAB), termed 7VC, that distinguishes between copper-free and -bound octarepeats. As determined by surface plason resonance, an epitope shielding effect in the presence of copper or zinc was only observed for peptides containing more than two consecutive octarepeats, suggesting that 7VC is a conformation-dependent ligand that senses the structural rearrangement that occurs in the octarepeat domain upon copper binding. The copper-dependent decrease of PrP binding was also observed in immuno-precipitation experiments from hamster brain homogenates. We observed that part of the epitope shielding effect was caused by intermolecular interactions between octarepat regions from different PrP molecules. Remarkably, the binding affinity but not the copper sensitivity of 7VC were found to be diminished when expanded octarepeat fragments were tested.
These data suggest that copper/zinc binding induces PrPc molecules to adopt one or more conformations, a property that can be thought of as a "copper switch", that have distinct reversible interactions with other proteins, such as 7VC, or with other PrP molecules. The latter interaction may allow PrPc molecules to form clusters in vivo, an event that might feature in either cellular homeostasis or formation of prions.
Supported by the BMBF, Germany, and a grant from the NINDS of the NIH, USA
AD S. Rutger Leliveld, Ralf Klingenstein, Carsten Korth, Institute for Neuropathology, Heinrich Heine University of Duesseldorf, Germany; Vishwanath R. Lingappa, Departments of Physiology and Medicine, University of California, San Francisco, USA
SP englisch
PO Deutschland
OR Tagungsband