Superoxide reduction by a superoxide reductase lacking the highly conserved lysine residue
- Univ. Nova de Lisboa, Oeiras (Portugal)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Univ. Nova de Lisboa, Oeiras (Portugal); Karolinska Inst., Stockholm (Sweden)
- Univ. Regensburg, Regensburg (Germany)
Superoxide reductases (SORs) are the most recently identified superoxide detoxification systems, being found in microorganisms from the three domains of life. These enzymes are characterized by a catalytic mononuclear iron site, with one cysteine and four histidine ligands of the ferrous active form. A lysine residue in the –EKHVP– motif, located close to the active site, has been considered to be essential for the enzyme function, by contributing to the positive surface patch that attracts the superoxide anion and by controlling the chemistry of the catalytic mechanism through a hydrogen bond network. However, we show here that this residue is substituted by non-equivalent amino acids in several putative SORs from Archaea and unicellular Eukarya. In this work, we focus on mechanistic and spectroscopic studies of one of these less common enzymes, the SOR from the hyperthermophilic crenarchaeon Ignicoccus hospitalis. We employ pulse radiolysis fast kinetics and spectroscopic approaches to study the wild-type enzyme (₋E₂₃T₂₄HVP₋), and two mutants, T24K and E23A, the later mimicking enzymes lacking both the lysine and glutamate (a ferric ion ligand) of the motif. The efficiency of the wild type protein and mutants in reducing superoxide is comparable to other SORs, revealing the robustness of these enzymes to single mutations.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC00112704
- OSTI ID:
- 1182506
- Report Number(s):
- BNL-107428-2015-JA; R&D Project: CO-004; KC0304030
- Journal Information:
- JBIC Journal of Biological Inorganic Chemistry, Vol. 20, Issue 1; ISSN 0949-8257
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Rational redox tuning of transition metal sites: learning from superoxide reductase
|
journal | January 2019 |
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