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Members of the 2-oxoacid dehydrogenase multienzyme complex family play a key role in the pathways of central metabolism. Post-translational lipoylation of the dihydrolipoyl acyltransferase component of these com-plexes is essential for their activity, the lipoyllysine moiety performing the transfer of substrates and intermediates between the different active sites within these multienzyme systems. | A unique lipoylation system in the Archaea Lipoylation in Thermoplasma acidophilum requires two proteins Mareike G. Posner1 Abhishek Upadhyay2 Stefan Bagby2 David W. Hough1 and Michael J. Danson1 1 Centre for Extremophile Research University of Bath UK 2 Department of Biology and Biochemistry University of Bath UK Keywords 2-oxoacid dehydrogenase multienzyme complex Archaea lipoylation post-translationalmodification 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 m.j.danson@bath.ac.uk Website http www.bath.ac.uk cer Received 18 March 2009 revised 18 May 2009 accepted 22 May 2009 doi 10.1111 j.1742-4658.2009.07110.x Members of the 2-oxoacid dehydrogenase multienzyme complex family play a key role in the pathways of central metabolism. Post-translational lipoylation of the dihydrolipoyl acyltransferase component of these complexes is essential for their activity the lipoyllysine moiety performing the transfer of substrates and intermediates between the different active sites within these multienzyme systems. We have previously shown that the thermophilic archaeon Thermoplasma acidophilum has a four-gene cluster encoding the components of such a complex which when recombinantly expressed in Escherichia coli can be assembled into an active multienzyme in vitro. Crucially the E. coli host carries out the required lipoylation of the archaeal dihydrolipoyl acyltransferase component. Because active 2-oxoacid dehydrogenase multienzyme complexes have never been detected in any archaeon the question arises as to whether Archaea possess a functional lipoylation system. In this study we report the cloning and heterologous expression of two genes from Tp. acidophilum whose protein products together show significant sequence identity with the single lipoate protein ligase enzyme of bacteria. We demonstrate that both recombinantly .
