NR AWXU
AU Kenward,A.G.; Bartolotti,L.J.; Burns,C.S.
TI Copper and zinc promote interactions between membrane-anchored peptides of the metal binding domain of the prion protein
QU Biochemistry 2007 Apr 10; 46(14): 4261-71
PT journal article; research support, non-u.s. gov't; research support, u.s. gov't, non-p.h.s.
AB The prion protein (PrP) has been identified as a metalloprotein capable of binding multiple copper ions and possibly zinc. Recent studies now indicate that prion self-recognition may be an important factor in both the normal function and misfunction of this protein. We have developed fluorescently labeled models of the prion protein that allow prion-prion interactions and metal binding to be investigated on the molecular level. Peptides encompassing the full metal binding region were anchored to the surface of small unilamellar vesicles, and PrP-PrP interactions were monitored by fluorescence spectroscopy as a function of added metal. Both Cu2+ and Zn2+ were found to cause an increase in the level of PrP-PrP interactions, by 117 and 300%, respectively, whereas other metals such as Ni2+, Co2+, and Ca2+ had no effect. The binding of either of these cofactors appears to act as a switch that induces PrP-PrP interactions in a reversible manner. Both glutamine and tryptophan residues, which occur frequently in the metal binding region of PrP, were found to be important in mediating PrP-PrP interactions. Experiments demonstrate that tryptophan residues are also responsible for the low level of PrP-PrP interactions observed in the absence of Cu2+ and Zn2+, and this is further supported by molecular modeling. Overall, our results indicate that PrP may be a bifunctional molecule capable of responding to fluctuations in both neuronal Cu2+ and Zn2+ levels.
MH Amino Acid Sequence; Binding Sites; Computer Simulation; Copper/*chemistry/metabolism; Crystallography, X-Ray; Dimyristoylphosphatidylcholine/chemistry; Electrostatics; Glutamic Acid/chemistry/metabolism; Liposomes; Models, Molecular; Molecular Sequence Data; Molecular Structure; Peptide Fragments/chemical synthesis/chemistry/*metabolism; Prions/*chemistry/metabolism; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Pyrenes/chemistry; Solvents/chemistry; Spectrometry, Fluorescence; Tryptophan/chemistry/metabolism; Water/chemistry; Zinc/*chemistry/metabolism
AD Department of Chemistry, East Carolina University, Greenville, North Carolina 27858, USA.
SP englisch
PO USA