A zinc-finger like metal binding site in the nucleosome.
UV spectroscopy demonstrated that chicken mononucleosomes bind Co(II) and Zn(II) ions at submicromolar concentrations in a tetrahedral mode, at a conserved zinc finger-like site, composed of Cys110 and His113 residues of both H3 molecules. Neither of these metal ions substituted for another, indicating a limited binding reversibility. Molecular modeling indicated that the tetrahedral site is formed by unhindered rotations around Calpha-Cbeta bonds in the side chains of the zinc binding residues. The resulting local rearrangement of the protein structure shields the bound metal ion from the solvent, explaining the observed lack of reversibility of the binding. Consequences of these findings for zinc homeostasis, metal toxicology and nucleosomal regulation are discussed.
Adamczyk
Małgorzata
M
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland.
Poznański
Jarosław
J
Kopera
Edyta
E
Bal
Wojciech
W
D000818:Animals; D001665:Binding Sites; D002645:Chickens; D003035:Cobalt / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006657:Histones / Q000737:chemistry*; D008958:Models, Molecular; D009707:Nucleosomes / Q000737:chemistry*; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D015032:Zinc / Q000737:chemistry*; D016335:Zinc Fingers
D006657:Histones; D009707:Nucleosomes; D003035:Cobalt; D006639:Histidine; D015032:Zinc; D003545:Cysteine