The Mechanism of Superoxide Scavenging by Archaeoglobus fulgidus Neelaredoxin

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

Neelaredoxin is a mononuclear iron protein wide-spread among prokaryotic anaerobes and facultative aerobes, including human pathogens. It has superoxide scavenging activity, but the exact mechanism by which this process occurs has been controversial. In this report, we present the study of the reaction of superoxide with the reduced form of neelaredoxin from the hyperthermophilic archaeon Archaeoglobus fulgidus by pulse radiolysis. This protein reduces superoxide very efficiently (k = 1.5 × 109 m-1s -1), and the dismutation activity is rate-limited, in steady-state conditions, by the much slower superoxide oxidation step. These data show unambiguously that the superfamily of neelaredoxin-like proteins (including desulfoferrodoxin) presents a novel type of reactivity toward superoxide, a result of particular relevance for the understanding of both oxygen stress response mechanisms and, in particular, how pathogens may respond to the oxidative burst produced by the defense cells in eukaryotes. The actual in vivo functioning of these enzymes will depend strongly on the cell redox status. Further insight on the catalytic mechanism was obtained by the detection of a transient intermediate ferric species upon oxidation of neelaredoxin by superoxide, detectable by visible spectroscopy with an absorption maximum at 610 nm, blue-shifted ∼50 nm from the absorption of the resting ferric state. The role of the iron sixth ligand, glutamate-12, in the reactivity of neelaredoxin toward superoxide was assessed by studying two site-directed mutants: E12Q and E12V.

Original languageEnglish
Pages (from-to)38995-39001
Number of pages7
JournalJournal of Biological Chemistry
Volume276
Issue number42
DOIs
Publication statusPublished - 19 Oct 2001

Keywords

  • Radiolysis
  • Scavenging
  • Enzymes
  • Cells
  • Mutagenesis
  • Proteins

Fingerprint

Dive into the research topics of 'The Mechanism of Superoxide Scavenging by Archaeoglobus fulgidus Neelaredoxin'. Together they form a unique fingerprint.

Cite this