Interaction of selected divalent metal ions with human ataxin-3 Q36.
The mode of interaction of ataxin-3 Q36 (AT-3 Q36) with selected endogenous and exogenous metal ions, namely, Zn(2+), Cu(2+), Ni(2+), and Cd(2+), was examined. Metal-ion-induced structural changes of the protein were monitored by fluorescence as well as Fourier transform Raman spectroscopy. We found that the cations tested lead to a decrease in alpha-helical content and a concurrent increase in beta-sheet as well as undefined (beta-turn and random-coil) structures. The most evident effect was observed for copper and nickel cations. After titration with these cations, the AT3 Q36 secondary structure content (27% alpha-helices in the presence of either ion, 31 and 27% beta-sheets for Cu(2+) and Ni(2+), respectively) was similar to that observed for the aggregated form of the protein (27% alpha-helices, 36% beta-sheets). Using the 1-anilinonaphthalene-8-sulfonate hydrophobic fluorescence probe, we showed that the presence of the metal ions tested led to the formation of solvent-exposed hydrophobic patches of AT-3 Q36, and that such an effect decreased with increasing ionic radius.
Stawoska
Iwona
I
Department of Inorganic Chemistry, Faculty of Chemistry, Jagiellonian University, 30-060 Kraków, Poland. stawoska@chemia.uj.edu.pl
Wesełucha-Birczyńska
Aleksandra
A
Regonesi
Maria Elena
ME
Riva
Matteo
M
Tortora
Paolo
P
Stochel
Grazyna
G
D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D000818:Animals; D001059:Apoproteins / Q000737:chemistry; D000067699:Ataxin-3; D002413:Cations, Divalent / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D006736:Horses; D006801:Humans; D008670:Metals / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics; D020033:Protein Isoforms / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics; D013050:Spectrometry, Fluorescence
D000817:Anilino Naphthalenesulfonates; D001059:Apoproteins; D002413:Cations, Divalent; D005456:Fluorescent Dyes; D008670:Metals; D009211:Myoglobin; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D012097:Repressor Proteins; C010857:apomyoglobin; C027132:1-anilino-8-naphthalenesulfonate; C092341:ATXN3 protein, human; D000067699:Ataxin-3