Arsenite oxidase, an ancient bioenergetic enzyme?
ATPase Electron transfer chain H+H+
Hélice transmembranaire Cluster [2Fe-2S] Domaine soluble
Ellis et al Structure 9, arsenite oxidase from Alcaligenes faecalis
Distribution of arsenite oxidases on the phylo tree of species
ssu-rRNA:
Chloroflexus aurantiacus - thermophilic photosynthetic bacterium (affiliated to Thermus-group) - isolated from a Yellowstone Park hot spring - earliest branching phototroph in standard ssu rRNA-trees - genome sequenced no bc-complex in Chloroflexus (genome), sole Rieske protein in the arsenite oxidase operon Inital results: - Rieske protein is membrane-associated (no RPE signal in supernatant) - Rieske protein can be light-oxidised, i.e. electrons from As III oxidation enter the photosynthetic electron transfer chain
ATPase Electron transfer chain H+H+
ATPase H+H+ Chloroflexus in the presence of arsenite h arsox AuCy mena- quinone ? As III As V photo- system + -
Mo ? [3Fe4S] Rieske AuCy P/P + (photosystem) E m (mV) ? 300 Mo [3Fe4S] Rieske cyt c oxidase Alcaligenes faecalis As III / As V Chloroflexus aurantiacus ?
BIP 09/CNRS Marseile Frauke Baymann (CR1) Anne-Lise Ducluzeau (Mastère) Simon Duval (Mastère) Evelyne Lebrun (CR1) Wolfgang Nitschke (DR2) Barbara Schoepp (CR1)