TAILIEUCHUNG - Báo cáo khoa học: The 2-oxoacid dehydrogenase multi-enzyme complex of the archaeon Thermoplasma acidophilum ) recombinant expression, assembly and characterization

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. | ễFEBS Journal The 2-oxoacid dehydrogenase multi-enzyme complex of the archaeon Thermoplasma acidophilum - recombinant expression assembly and characterization Caroline Heath1 Mareike G. Posner1 Hans C. Aass1 Abhishek Upadhyay2 David J. Scott3 David W. Hough1 and Michael J. Danson1 1 Centre for Extremophile Research Department of Biology and Biochemistry University of Bath UK 2 Department of Biology and Biochemistry University of Bath UK 3 NationalCentre for Macromolecular Hydrodynamics Schoolof Biosciences University of Nottingham Sutton Bonington UK Keywords Archaea metabolism multi-enzyme complex 2-oxoacid dehydrogenase thermophile Correspondence M. J. Danson Centre for Extremophile Research Department of Biology and Biochemistry University of Bath Bath BA2 7AY UK Fax 44 1225 386779 Tel 44 1225 386509 E-mail Received 29 June 2007 revised 23 August 2007 accepted 24 August 2007 doi 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 multienzyme complexes. However catalytic activities of such complexes have never been detected in the archaea although 2-oxoacid ferredoxin oxidore-ductases 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 Mr 5 X 106 multienzyme 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 .

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