title: The -Cys-Cys- motif in Helicobacter pylori's Hpn and HspA proteins is an essential anchoring site for metal ions.
abstract: The Hpn and HspA proteins from H. pylori are significant for nickel homeostasis and protect the cells from higher concentrations of external metal ions. Both proteins have a unique histidine- and cysteine-rich domain at the C terminus. The interactions of Ni(2+), Bi(3+), Zn(2+) and Cd(2+) ions with C-terminal Ac-CCSTSDSHHQ-NH(2) and Ac-EEGCCHGHHE-NH(2) fragments from Hpn and the Ac-GSCCHTGNHD-NH(2) sequence from HspA were studied by potentiometry, mass spectrometry, circular dichroism and UV-Vis spectroscopy. Ac-CC-NH(2) was used as a reference peptide. The studies have shown that nickel ions form planar complexes with a {2S(-),N(-)} binding mode. The thiol sulfurs of the -Cys-Cys- motif are also the anchoring sites for Bi(3+), Zn(2+) and Cd(2+) ions. The studied protein fragments have the highest affinity for Bi(3+) ions. The thermodynamic stability of Ni(2+) is much higher then that of Zn(2+).
authors.affiliation: Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50383, Wroclaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Rowinska-Zyrek
authors.forename: Danuta
authors.initials: D
authors.lastname: Witkowska
authors.forename: Sylwia
authors.initials: S
authors.lastname: Bielinska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kamysz
authors.forename: Henryk
authors.initials: H
authors.lastname: Kozlowski
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001729:Bismuth / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry; D002942:Circular Dichroism; D056831:Coordination Complexes / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D016480:Helicobacter pylori / Q000378:metabolism*; D007477:Ions / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D008969:Molecular Sequence Data; D009532:Nickel / Q000737:chemistry; D011199:Potentiometry; D011485:Protein Binding; D013056:Spectrophotometry, Ultraviolet; D015032:Zinc / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D056831:Coordination Complexes; D004151:Dipeptides; D006360:Heat-Shock Proteins; C113725:HspA protein, bacteria; D007477:Ions; D008670:Metals; D002104:Cadmium; C046557:cysteinylcysteine; D009532:Nickel; D015032:Zinc; D001729:Bismuth