Abreu, Isabel A. and Saraiva, Ligia M. and Carita, Joao and Huber, H. and Stetter, Karl Otto and Cabelli, Diane and Teixeira, Miguel (2000) Oxygen detoxification in the strict anaerobic archaeon Archaeoglobus fulgidus: superoxide scavenging by Neelaredoxin. MOLECULAR MICROBIOLOGY, 38 (2). pp. 322-334. ISSN 0950-382X
Full text not available from this repository. (Request a copy)Abstract
Archaeoglobus fulgidus is a hyperthermophilic sulphate-reducing archaeon. It has an optimum growth temperature of 83 degreesC and is described as a strict anaerobe. Its genome lacks any homologue of canonical superoxide (O-2 .(-)) dismutases. In this work, we show that neelaredoxin (Nlr) is the main O-2 .(-) scavenger in A. fulgidus, by studying both the wild-type and recombinant proteins. Nlr is a 125-amino-acid blue-coloured protein containing a single iron atom/molecule, which in the oxidized state is high spin ferric. This iron centre has a reduction potential of +230 mV at pH 7.0. Nitroblue tetrazolium-stained gel assays of cell-soluble extracts show that Nlr is the main protein from A. fulgidus which is reactive towards O-2 .(-). Furthermore, it is shown that Nlr is able to both reduce and dismutate O-2 .(-), thus having a bifunctional reactivity towards O-2 .(-). Kinetic and spectroscopic studies indicate that Nlr's superoxide reductase activity may allow the cell to eliminate O-2 .(-) quickly in a NAD(P)H-dependent pathway. On the other hand, Nlr's superoxide dismutation activity will allow the cell to detoxify O-2 .(-) independently of the cell redox status. Its superoxide dismutase activity was estimated to be 59 U mg(-1) by the xanthine/xanthine oxidase assay at 25 degreesC. Pulse radiolysis studies with the isolated and reduced Nlr proved unambiguously that it has superoxide dismutase activity; at pH 7.1 and 83 degreesC, the rate constant is 5 x 10(6) M-1 s(-1). Besides the superoxide dismutase activity, soluble cell extracts of A. fulgidus also exhibit catalase and NAD(P)H/oxygen oxidoreductase activities. By putting these findings together with the entire genomic data available, a possible oxygen detoxification mechanism in A. fulgidus is discussed.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DESULFOVIBRIO-DESULFURICANS ATCC-27774; NONHEME IRON PROTEIN; RBO GENE-PRODUCT; ESCHERICHIA-COLI; GIGAS; RUBREDOXIN; DISMUTASE; DESULFOFERRODOXIN; DESULFOREDOXIN; PURIFICATION; |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie > Lehrstuhl für Mikrobiologie (Archaeenzentrum) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 23 Mar 2022 06:08 |
| Last Modified: | 23 Mar 2022 06:08 |
| URI: | https://pred.uni-regensburg.de/id/eprint/42186 |
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