NR ATHS
AU Treiber,C.; Pipkorn,R.; Simons,A.; Özel,M.; Multhaup,G.
TI Protease-resistant PrP molecules generated in yeast
QU International Conference - Prion 2005: Between fundamentals and society's needs - 19.10.-21.10.2005, Congress Center Düsseldorf - Poster Session: Cell Biology of PrPc and PrPsc CELL-24
PT Konferenz-Poster
AB
There is overwhelming evidence that the prion protein PrPc is a metallo protein. Whereas over-expression of PrPc does not have a dramatic effect on Cu metabolism, crude membranes and synaptosomal fractions of the brains of mice lacking the expression of PrPc have a major deficit in Cu. In vitro, Mn binding to PrPc leads to its conversion into an abnormal form of PrP rich in beta-sheet and with resistance to proteinase K digestion. It was suggested that an imbalance in brain trace elements, such as the loss of Cu and an excess of Mn might result in conditions that lead to the formation of PrPsc.
Expression of PrP23-230 per se led to a doubling of intracellular Cu levels whereas Mn levels decreased 2-fold. Under these conditions PrP23-230 was almost completely proteinase K sensitive. Analysis of yeast cells grown in Cu or Mn supplemented medium further supported an active role for PrP23-230 in metal ion homeostasis, especially in decreasing intracellular Cu levels. The treatment with proteinase K revealed that Cu or Mn was required for the structural transition of recombinant PrP molecules into the protease-resistant PrP conformation in yeast cells.
In contrast to protease-resistant conformations of PrP generated in vitro, the formation of new protease-resistant PrP molecules generated in vivo were structurally not interconvertible. PrP charged with Cu and/or Mn in vivo during cellular growth maintained its protease-resistant PrPres conformation even in the presence of EDTA. This effect was specific for Cu and Mn because other PrP binding metal ions such as Co did not induce PrPres formation. Our discovery that PrPres molecules generated in vivo have stable structures indicates that differences may exist in protease resistance even between PrPsc molecules. PrPres molecules from yeast may thus rather resemble the prions deposited in the brains of patients than PrPres with interconvertible molecular structures previosly produced in vitro.
AD C.Treiber, A.Simons, G.Multhaup, FU-Berlin, Germany; R.Pipkorn, DKFZ-German Cancer Research Center, Germany; M.Özel, Robert Koch Institut, Germany
SP englisch
PO Deutschland