rdlA, a new gene encoding a rhodanese-like protein in Halanaerobium congolense and other thiosulfate-reducing anaerobes.
The recently described anaerobic moderately halophilic bacterium Halanaerobium congolense has been shown to reduce thiosulfate and sulfur-but not sulfate-into sulfide. When cultivated in the presence of thiosulfate as terminal electron acceptor, H. congolense possesses a highly active thiosulfate:cyanide sulfur-transferase activity (rhodanese-like enzyme). A gene library of H. congolense (DSM 11287T) was constructed, and a 3.1-kb Sau3A DNA that encompassed a thiosulfate:cyanide sulfur-transferase-encoding gene was isolated in Escherichia coli. This fragment contains 2 orfs, which were separately subcloned in E. coli. The 900-bp gene encoding the rhodanese-like protein was named rdlA. RdlA differs from other known rhodanese-like proteins by having two potential catalytic sites, one N-terminal and one C-terminal, both harboring a cysteine. The two putative active sites are preceded by a highly-conserved region of unknown function. Closely related genes were also characterized in other thiosulfate-reducing non-sulfate-reducing anaerobes belonging to phylogenetically distant microorganisms, thus suggesting that RdlA is of importance in the mechanism of thiosulfate reduction by numerous members of the domain Bacteria.
Ravot
Gilles
G
Sanofi-Synthélabo Recherche, 31676 Labège Cedex, France.
Casalot
Laurence
L
Ollivier
Bernard
B
Loison
Gérard
G
Magot
Michel
M
D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017422:Sequence Analysis, DNA; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013885:Thiosulfates / Q000378:metabolism*
D001426:Bacterial Proteins; D013885:Thiosulfates; D013884:Thiosulfate Sulfurtransferase