Abstract
Those aerobic archaea whose genomes have been sequenced possess a single 4-gene operon that, by sequence comparisons with Bacteria and Eukarya, appears to encode the three component enzymes of a 2-oxoacid dehydrogenase multienzyme complex. However, no catalytic activity of any such complex has ever been detected in the Archaea. In the current paper, we have cloned and expressed the first two genes of this operon from the thermophilic archaeon, Thermoplasma acidophilum. We demonstrate that the protein products form an alpha2beta2 hetero-tetramer possessing the decarboxylase catalytic activity characteristic of the first component enzyme of a branched-chain 2-oxoacid dehydrogenase multienzyme complex. This represents the first report of the catalytic function of these putative archaeal multienzyme complexes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Archaeal Proteins / chemistry
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Archaeal Proteins / genetics
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Archaeal Proteins / metabolism*
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Base Sequence
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Catalysis
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Chromatography, Gel
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Cloning, Molecular
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Codon, Initiator / chemistry
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Computational Biology
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Densitometry
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Escherichia coli / genetics
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Gene Expression
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Genes, Bacterial
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Ketone Oxidoreductases / chemistry
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Ketone Oxidoreductases / genetics
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Ketone Oxidoreductases / metabolism*
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Kinetics
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Molecular Sequence Data
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Multienzyme Complexes / chemistry
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Multienzyme Complexes / genetics
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Multienzyme Complexes / metabolism*
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Open Reading Frames
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Operon
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Spectrophotometry
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Thermoplasma / enzymology*
Substances
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Archaeal Proteins
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Codon, Initiator
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Multienzyme Complexes
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Recombinant Proteins
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Ketone Oxidoreductases