Download MendeleyA [3Cu:2S] cluster provides insight into the assembly and function of the Cu Z site of nitrous oxide reductase.
Zhang, L., Bill, E., Kroneck, P.M.H., Einsle, O.(2021) Chem Sci 12: 3239-3244
- PubMed: 34164092
- DOI: https://doi.org/10.1039/d0sc05204c
- Primary Citation of Related Structures:
6Y6Y, 6Y71, 6Y72, 6Y77, 6Y7D, 6Y7E, 7AQA - PubMed Abstract:
Nitrous oxide reductase (N 2 OR) is the only known enzyme reducing environmentally critical nitrous oxide (N 2 O) to dinitrogen (N 2 ) as the final step of bacterial denitrification. The assembly process of its unique catalytic [4Cu:2S] cluster Cu Z 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 N 2 OR in Escherichia coli . While no copper ion was found in the Cu Z 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, S Z2 , 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 S Z2 may have been observed before, but not recognized. The sulfide shift changes the metal coordination in Cu Z and is thus of high mechanistic interest.
Organizational Affiliation:
Institut für Biochemie, Albert-Ludwigs-Universität Freiburg Albertstrasse 21 79104 Freiburg im Breisgau Germany [email protected].
