title: Selective interaction of Hpn-like protein with nickel, zinc and bismuth in vitro and in cells by FRET.
abstract: Hpn-like (Hpnl) is a unique histidine- and glutamine-rich protein found only in Helicobacter pylori and plays a role on nickel homeostasis. We constructed the fluorescent sensor proteins CYHpnl and CYHpnl_1-48 (C-terminal glutamine-rich region truncated) using enhanced cyan and yellow fluorescent proteins (eCFP and eYFP) as the donor-acceptor pair to monitor the interactions of Hpnl with metal ions and to elucidate the role of conserved Glu-rich sequence in Hpnl by fluorescence resonance energy transfer (FRET). CYHpnl and CYHpnl_1-48 exhibited largest responses towards Ni(II) and Zn(II) over other metals studied and the binding of Bi(III) to CYHpnl was observed in the presence of an excess amount of Bi(III) ions (Kd=115±4.8 μM). Moreover, both CYHpnl and CYHpnl_1-48 showed positive FRET responses towards the binding to Ni(II) and Zn(II) in Escherichia coli cells overexpressing CYHpnl and CYHpnl_1-48, whereas a decrease in FRET upon Bi(III)-binding in E. coli cells overexpressing the latter. Our study provides clear evidence on Hpnl binding to nickel in cells, and intracellular interaction of Hpnl with Bi(III) could disrupt the protein function, thus probably contributing to the efficacy of Bi(III) drugs against H. pylori.
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Yuen-Yan
authors.initials: YY
authors.lastname: Chang
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Yau-Tsz
authors.initials: YT
authors.lastname: Lai
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Tianfan
authors.initials: T
authors.lastname: Cheng
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China. Electronic address: hsun@hku.hk.
authors.forename: Hongzhe
authors.initials: H
authors.lastname: Sun
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001729:Bismuth / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D016480:Helicobacter pylori; D019216:Metals, Heavy / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D015032:Zinc / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D019216:Metals, Heavy; D009532:Nickel; D015032:Zinc; D001729:Bismuth
keywords: FRET; Metal selectivity; Metallodrugs; Metalloproteins; Nickel storage