A [3Cu:2S] cluster provides insight into the assembly and function of the CuZ site of nitrous oxide reductase
Autor: | Lin Zhang, Eckhard Bill, Oliver Einsle, Peter M. H. Kroneck |
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Jazyk: | angličtina |
Rok vydání: | 2021 |
Předmět: |
chemistry.chemical_classification
Denitrification biology Sulfide 010405 organic chemistry Chemistry Hydrogen bond Stereochemistry chemistry.chemical_element Nitrous-oxide reductase General Chemistry 010402 general chemistry biology.organism_classification 01 natural sciences Copper 0104 chemical sciences Pseudomonas stutzeri ddc:570 Binding site Histidine |
Popis: | Nitrous oxide reductase (N2OR) is the only known enzyme reducing environmentally critical nitrous oxide (N2O) to dinitrogen (N2) as the final step of bacterial denitrification. The assembly process of its unique catalytic [4Cu:2S] cluster CuZ remains scarcely understood. Here we report on a mutagenesis study of all seven histidine ligands coordinating this copper center, followed by spectroscopic and structural characterization and based on an established, functional expression system for Pseudomonas stutzeri N2OR in Escherichia coli. While no copper ion was found in the CuZ binding site of variants H129A, H130A, H178A, H326A, H433A and H494A, the H382A variant carried a catalytically inactive [3Cu:2S] center, in which one sulfur ligand, SZ2, had relocated to form a weak hydrogen bond to the sidechain of the nearby lysine residue K454. This link provides sufficient stability to avoid the loss of the sulfide anion. The UV-vis spectra of this cluster are strikingly similar to those of the active enzyme, implying that the flexibility of SZ2 may have been observed before, but not recognized. The sulfide shift changes the metal coordination in CuZ and is thus of high mechanistic interest. published |
Databáze: | OpenAIRE |
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