The zinc-binding fragment of HypA from Helicobacter pylori: a tempting site also for nickel ions

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 42; no. 17; pp. 6012 - 6020
• Main Authors: Rowinska-Zyrek, Magdalena, Potocki, Slawomir, Witkowska, Danuta, Valensin, Daniela, Kozlowski, Henryk
• Format: Journal Article
• Language: English
• Published: England 07.05.2013
• Subjects: Amino Acid Motifs; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Cadmium; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Circular Dichroism; Coordination Complexes - chemistry; Coordination Complexes - metabolism; Helicobacter pylori; Helicobacter pylori - metabolism; Ions - chemistry; Molecular Sequence Data; Nickel - chemistry; Nickel - metabolism; Protein Binding; Sequence Alignment; Thermodynamics; Zinc - chemistry; Zinc - metabolism
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt32195e

HypA, a nickel accessory protein from H. pylori, binds a zinc ion in it's structural site, a loop with two conserved CXXC motifs (Ac-ELECKDCSHVFKPNALDYGVCEKCHS-NH(2)). There are at least three hypotheses on the binding mode of this ion. In this paper, we try to understand how Zn(2+) binds to this fragment and why Ni(2+), a metal with quite a high affinity towards thiolic sites, doesn't compete with zinc in the binding to this motif. Potentiometric titrations, mass spectrometry, NMR, UV-Vis and CD spectroscopy help us to compare the coordination modes in both metal complexes and discuss their thermodynamic stabilities.