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A 35 kDa NAD(P)H oxidase previously isolated from the archaeon Sulfolobus solfataricus is instead a thioredoxin reductase.
- Source :
-
Biochimie [Biochimie] 2004 Dec; Vol. 86 (12), pp. 883-92. - Publication Year :
- 2004
-
Abstract
- A thioredoxin reductase (TrxR) has been identified in the hyperthermophilic archaeon Sulfolobus solfataricus (Ss). This enzyme is a homodimeric flavoprotein that was previously identified as NADH oxidase in the same micro-organism ('Biotechnol. Appl. Biochem. 23 (1996) 47'). The primary structure of SsTrxR is made of 323 amino acid residues and contains two putative betaalphabeta regions for the binding of FAD, and a NADP(H) binding consensus sequence in the proximity of a CXXC motif. These findings indicate that SsTrxR is structurally related to the class II of the pyridine nucleotide-disulphide oxidoreductases family. Moreover, the enzyme exhibits a NADP(H) dependent thioredoxin reductase activity requiring the presence of FAD. Surprisingly, the reductase activity of SsTrxR is reduced in the presence of a specific inhibitor of mammalian TrxR. This finding demonstrates that the archaeal enzyme, although structurally related to eubacterial TrxR, is functionally closer to eukaryal enzymes. Experimental evidences indicate that a disulphide bridge is required for the reductase but also for the NADH oxidase activity of the enzyme. These results are further supported by the significantly reduced activities exerted by the C147A mutant. The integrity of the CXXC motif is also involved in the stability of the enzyme.
- Subjects :
- Amino Acid Motifs
Amino Acid Sequence
Amino Acid Substitution
Base Sequence
Binding Sites
Cloning, Molecular
Consensus Sequence
Cysteine metabolism
Disulfides chemistry
Enzyme Stability
Flavin-Adenine Dinucleotide analysis
Kinetics
Molecular Sequence Data
Molecular Weight
Mutation
NADH, NADPH Oxidoreductases analysis
NADH, NADPH Oxidoreductases chemistry
NADH, NADPH Oxidoreductases genetics
NADH, NADPH Oxidoreductases metabolism
NADPH Oxidases
Sequence Homology, Amino Acid
Sulfolobus solfataricus chemistry
Sulfolobus solfataricus genetics
Temperature
Thioredoxin-Disulfide Reductase analysis
Thioredoxin-Disulfide Reductase genetics
Thioredoxin-Disulfide Reductase isolation & purification
Thioredoxin-Disulfide Reductase metabolism
Archaea enzymology
Archaea metabolism
NADH, NADPH Oxidoreductases isolation & purification
Sulfolobus solfataricus enzymology
Thioredoxin-Disulfide Reductase chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 0300-9084
- Volume :
- 86
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- Biochimie
- Publication Type :
- Academic Journal
- Accession number :
- 15667938
- Full Text :
- https://doi.org/10.1016/j.biochi.2004.10.008