Thermal perturbation of the dicluster ferredoxin from Acidianus ambivalens was investigated employing a toolbox of spectroscopic methods. FTIR and visible CD were used for assessing changes of the secondary structure and coarse alterations of the [3Fe4S] and [4Fe4S] cluster moieties, respectively. Fine details of the disassembly of the metal centers were revealed by paramagnetic NMR and resonan...

The 7598-bp plasmid pDL10 from the extremely thermophilic, acidophilic, and chemolithoautotrophic Archaeon Acidianus ambivalens was sequenced. It contains 10 open reading frames (ORFs) organized in five putative operons. The deduced amino acid sequence of the largest ORF (909 aa) showed similarity to bacterial Rep proteins known from phages and plasmids with rolling-circle (RC) replication. Fro...

BACKGROUND The sulfur oxygenase reductase (SOR) is the initial enzyme of the sulfur oxidation pathway in the thermoacidophilic Archaeon Acidianus ambivalens. The SOR catalyzes an oxygen-dependent sulfur disproportionation to H(2)S, sulfite and thiosulfate. The spherical, hollow, cytoplasmic enzyme is composed of 24 identical subunits with an active site pocket each comprising a mononuclear non-...

The hyperthermophilic archaeon Acidianus ambivalens expresses a membrane-bound aa(3)-type quinol oxidase, when grown aerobically, that we have studied by resonance Raman spectroscopy. The purified aa(3) oxidase, which does not contain bound quinol, undergoes a reversible slow conformational change at heme a(3) upon reduction, as indicated by a change in the frequency of its heme formyl stretchi...

The biological insertion of iron-sulfur clusters (Fe-S) involves the interaction of (metallo) chaperons with a partly folded target polypeptide. In this respect, the study of nonnative protein conformations in iron-sulfur proteins is relevant for the understanding of the folding process and cofactor assembly. We have investigated the formation of a molten globule state in the [3Fe4S][4Fe4S] fer...