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The 2‐oxoacid dehydrogenase multi‐enzyme complex of the archaeon Thermoplasma acidophilum − recombinant expression, assembly and characterization
Author(s) -
Heath Caroline,
Posner Mareike G.,
Aass Hans C.,
Upadhyay Abhishek,
Scott David J.,
Hough David W.,
Danson Michael J.
Publication year - 2007
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.06067.x
Subject(s) - thermoplasma acidophilum , biochemistry , archaea , enzyme , thermophile , biology , dehydrogenase , recombinant dna , gene
The aerobic archaea possess four closely spaced, adjacent genes that encode proteins showing significant sequence identities with the bacterial and eukaryal components comprising the 2‐oxoacid dehydrogenase multi‐enzyme complexes. However, catalytic activities of such complexes have never been detected in the archaea, although 2‐oxoacid ferredoxin oxidoreductases that catalyze the equivalent metabolic reactions are present. In the current paper, we clone and express the four genes from the thermophilic archaeon, Thermoplasma acidophilum , and demonstrate that the recombinant enzymes are active and assemble into a large ( M r = 5 × 10 6 ) multi‐enzyme complex. The post‐translational incorporation of lipoic acid into the transacylase component of the complex is demonstrated, as is the assembly of this enzyme into a 24‐mer core to which the other components bind to give the functional multi‐enzyme system. This assembled complex is shown to catalyze the oxidative decarboxylation of branched‐chain 2‐oxoacids and pyruvate to their corresponding acyl‐CoA derivatives. Our data constitute the first proof that the archaea possess a functional 2‐oxoacid dehydrogenase complex.