A novel NADPH-dependent oxidoreductase with a unique domain structure in the hyperthermophilic Archaeon, Thermococcus litoralis.
Thermococcus litoralis, a hyperthermophilic Archaeon, is able to reduce elemental sulfur during fermentative growth. An unusual gene cluster (nsoABCD) was identified in this organism. In silico analysis suggested that three of the genes (nsoABC) probably originated from Eubacteria and one gene (nsoD) from Archaea. The putative NsoA and NsoB are similar to NuoE- and NuoF-type electron transfer proteins, respectively. NsoC has a unique domain structure and contains a GltD domain, characteristic of glutamate synthase small subunits, which seems to be integrated into a NuoG-type sequence. Flavin and NAD(P)H binding sites and conserved cysteines forming iron-sulfur clusters binding motifs were identified in the protein sequences deduced. The purified recombinant NsoC contains one FAD cofactor per protein molecule and catalyzes the reduction of polysulfide with NADPH as an electron donor and it also reduces oxygen. It was concluded that the Nso complex is a new type of NADPH-oxidizing enzyme using sulfur and/or oxygen as an electron acceptor.
Tóth
András
A
Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary.
Takács
Mária
M
Groma
Géza
G
Rákhely
Gábor
G
Kovács
Kornél L
KL
D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D007700:Kinetics; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D009876:Operon; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019712:Thermococcus / Q000737:chemistry / Q000201:enzymology*; D024363:Transcription Initiation Site
D019843:Archaeal Proteins; D011994:Recombinant Proteins; D010088:Oxidoreductases; D009247:NADH, NADPH Oxidoreductases; C074883:polysulfide reductase