A new sulfurtransferase from the hyperthermophilic bacterium Aquifex aeolicus

Abstract

Sulfur is a functionally important element of living matter. Rhodanese is involved in the enzymatic production of the sulfane sulfur which has been suggested as the biological relevant active sulfur species. Rhodanese domains are ubiquitous structural modules occurring in the three major evolutionary phyla. We characterized a new single‐domain rhodanese with a thiosulfate : cyanide transferase activity, Aq‐477. Aq‐477 can also use tetrathionate and polysulfide. Thermoactivity and thermostability studies show that in solution Aquifex sulfurtranferase exists in equilibrium between monomers, dimers and tetramers, shifting to the tetrameric state in the presence of substrate. We show that oligomerization is important for thermostability and thermoactivity. This is the first characterization of a sulfurtransferase from a hyperthermophilic bacterium, which moreover presents a tetrameric organization. Oligomeric Aq‐477 may have been selected in hyperthermophiles because subunit association provides extra stabilization.

Nutritional stress induces exchange of cell material and energetic coupling between bacterial species

“…The experiments were carried out at least in triplicate. H 2 S concentration was determined as described in Giuliani et al 51 Real-time qPCR. After extraction of genomic DNA from D. vulgaris and C. acetobutylicum using the Wizard Genomic DNA Purification Kit (Promega), DNA purity and concentration were determined and the number of copies was determined by qPCR as described by Savichtcheva et al 52 The primers used for the qPCR (dsrA and endoG) are listed in Supplementary Reverse transcription PCR.…”

Rhodanese Functions as Sulfur Supplier for Key Enzymes in Sulfur Energy Metabolism

“…Escherichia coli BL21-CodonPlus (DE3)-RIPL, transformed with the pET22aq477 or pET22SOR plasmids, was grown in LB medium at 37°C supplemented with 0.5 mM ampicillin (12,26).…”

“…SbdP Purification-Recombinant SbdP was obtained from E. coli as described previously (26). Previous studies showed that recombinant SbdP behaves similarly to SbdP from A. aeolicus (26).…”

“…The presence of a rhodanese (Aq-477) of unknown function in the cytoplasmic compartment of A. aeolicus raised our curiosity about its potential role in this metabolism. Aq-477 presents in vitro the classical thiosulfate cyanide sulfurtransferase activity (26). Previous biochemical characterizations of Aq-477 have shown that it can also use in vitro at 85°C tetrathionate (S 4 O 6 2Ϫ ) and polysulfide instead of thiosulfate (S 2 O 3 2Ϫ ) as sulfur donor (26).…”

“…Aq-477 presents in vitro the classical thiosulfate cyanide sulfurtransferase activity (26). Previous biochemical characterizations of Aq-477 have shown that it can also use in vitro at 85°C tetrathionate (S 4 O 6 2Ϫ ) and polysulfide instead of thiosulfate (S 2 O 3 2Ϫ ) as sulfur donor (26). The existence of an equilibrium between monomers, dimers, and tetramers of Aq-477 has also been observed, and this oligomerization appears important for thermostability and thermoactivity, which is not surprising for a protein present in a hyperthermophilic bacterium (27,28).…”