Non-thiolate ligation of nickel by nucleotide-free UreG of Klebsiella aerogenes
| Autor: | Scott B. Mulrooney, Crisjoe A. Joseph, Jodi L. Boer, Robert P. Hausinger, Vlad Martin-Diaconescu, Michael J. Maroney |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Multiprotein complex Stereochemistry Dimer Protomer Enterobacter aerogenes Biochemistry Article Inorganic Chemistry 03 medical and health sciences Residue (chemistry) chemistry.chemical_compound Bacterial Proteins Nickel Klebsiella Imidazole Nucleotide Binding site chemistry.chemical_classification Binding Sites 030102 biochemistry & molecular biology biology Chemistry Phosphate-Binding Proteins biology.organism_classification Zinc 030104 developmental biology Carrier Proteins |
| Zdroj: | JBIC Journal of Biological Inorganic Chemistry. 22:497-503 |
| ISSN: | 1432-1327 0949-8257 |
| Popis: | Nickel-dependent ureases are activated by a multiprotein complex that includes the GTPase UreG. Prior studies showed that nucleotide-free UreG from Klebsiella aerogenes is monomeric and binds one nickel or zinc ion with near-equivalent affinity using an undefined binding site, whereas nucleotide-free UreG from Helicobacter pylori selectively binds one zinc ion per dimer via a universally conserved Cys-Pro-His motif in each protomer. Iodoacetamide-treated K. aerogenes UreG was nearly unaffected in nickel binding compared to non-treated sample, suggesting the absence of thiolate ligands to the metal. X-ray absorption spectroscopy of nickel-bound UreG showed the metal possessed four-coordinate geometry with all O/N donor ligands including one imidazole, thus confirming the absence of thiolate ligation. The nickel site in Strep-tag II-modified protein possessed six-coordinate geometry, again with all O/N donor ligands, but now including two or three imidazoles. An identical site was noted for the Strep-tag II-modified H74A variant, substituted in the Cys-Pro-His motif, ruling out coordination by this His residue. These results are consistent with metal binding to both His6 and a His residue of the fusion peptide in Strep-tagged K. aerogenes UreG. We conclude that the nickel- and zinc-binding site in nucleotide-free K. aerogenes UreG is distinct from that of nucleotide-free H. pylori UreG and does not involve the Cys-Pro-His motif. Further, we show the Strep-tag II can perturb metal coordination of this protein. |
| Databáze: | OpenAIRE |
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