Effects of divalent metal ions on the alphaB-crystallin chaperone-like activity: spectroscopic evidence for a complex between copper(II) and protein.
AlphaB-crystallin is a small heat shock protein, showing chaperone-like activity, that is expressed in the lens and in several other tissues. The role of some metal ions in the alphaB-crystallin biology starts to be well documented. In some neuro-degenerative pathologies, like Parkinson and Alzheimer's diseases, alphaB-crystallin is expressed at high levels. In the same pathologies an accumulation of divalent metal cations is observed. In order to investigate the interactions between human alphaB-crystallin and divalent metal ions, the effect of copper, zinc and calcium on the chaperone-like activity of the protein has been studied. Copper and zinc at concentrations 0.1 and 1 mM significantly increase the chaperone-like activity, whereas calcium 1 mM completely inhibits activity. Electron paramagnetic resonance (EPR) and circular dichroism (CD) spectra indicate the possible complex formation between Cu(II) and protein at physiological pH. Molecular modeling calculations, carried out for the probable Cu(II) binding site, suggest that a complex with three histidine residues is possible.
Ganadu
Maria Luisa
ML
Dipartimento di Chimica, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy. ganadu@ssmain.uniss.it
Aru
Michaela
M
Mura
Giovanni Maria
GM
Coi
Alessio
A
Mlynarz
Piotr
P
Kozlowski
Henryk
H
D000544:Alzheimer Disease / Q000378:metabolism; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007381:Intermediate Filament Proteins / Q000737:chemistry* / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D010300:Parkinson Disease / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D038203:alpha-Crystallin B Chain
C059215:CRYAB protein, human; D007381:Intermediate Filament Proteins; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; D038203:alpha-Crystallin B Chain; D003300:Copper; D011494:Protein Kinases