Binding of Ni2+ to a histidine- and glutamine-rich protein, Hpn-like

Zeng, Yi-Bo, Zhang, Dong-Mei, Li, Hongyan and Sun, Hongzhe 2008. Binding of Ni2+ to a histidine- and glutamine-rich protein, Hpn-like. Journal of Biological Inorganic Chemistry 13 (7) , 1121. 10.1007/s00775-008-0397-0

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Abstract

Hpn-like (Hpnl) protein, encoded by the hpnl gene in Helicobacter pylori and featuring a histidine-rich and two glutamine-rich motifs, can render nickel tolerance to H. pylori when the external nickel level reaches toxic limits. We found that the recombinant Hpnl exists as an oligomer in the native state and binds to two molar equivalents of nickel ions per monomer with a dissociation constant of 3.8 μM. Nickel could be released from Hpnl either at acidic pH (pH1/2 4.6) or in the presence of chelate ligands, such as EDTA (t 1/2 = 220, 355, and 716 min at pH 6.0, 7.0, and 7.5, respectively). Our combined spectroscopic data show that nickel ion coordinates to a nitrogen of a histidine residue possibly with a coordination number of four (square-planar geometry) or five. The growth of Escherichia coli cells with or without the hpnl gene implied a protective role of Hpnl under higher concentrations of external nickel ions. Hpnl may serve a role in binding/storage or detoxification of excess nickel ions.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Publisher:	Springer Verlag (Germany)
ISSN:	0949-8257
Date of Acceptance:	4 June 2008
Last Modified:	03 Feb 2021 15:16
URI:	https://orca.cardiff.ac.uk/id/eprint/138156

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