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Restricted motion of the lipoyl-lysine swinging arm in the pyruvate dehydrogenase complex of Escherichia coli†,‡

Jones, D. Dafydd ORCID:, Stott, Katherine M., Howard, Mark J. and Perham, Richard N. 2000. Restricted motion of the lipoyl-lysine swinging arm in the pyruvate dehydrogenase complex of Escherichia coli†,‡. Biochemistry 39 (29) , 8448–8459. 10.1021/bi992978i

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The three lipoyl (E2plip) domains of the dihydrolipoyl acetyltransferase component of the pyruvate dehydrogenase (PDH) complex of Escherichia coli house the lipoyl-lysine side chain essential for active-site coupling and substrate channelling within the complex. The structure of the unlipoylated form of the innermost domain (E2plipapo) was determined by multidimensional NMR spectroscopy and found to resemble closely that of a nonfunctional hybrid domain determined previously [Green et al. (1995) J. Mol. Biol. 248, 328−343]. The domain comprises two four-stranded β-sheets, with the target lysine residue residing at the tip of a type-I β-turn in one of the sheets; the N- and C-termini lie close together at the opposite end of the molecule in the other β-sheet. Measurement of 15N NMR relaxation parameters and backbone hydrogen/deuterium (H/D) exchange rates reveals that the residues in and surrounding the lipoyl-lysine β-turn in the E2plipapo form of the domain become less flexible after lipoylation of the lysine residue. This implies that the lipoyl-lysine side chain may not sample the full range of conformational space once thought. Moreover, reductive acetylation of the lipoylated domain (E2plipholo → E2plipredac) was accompanied by large changes in chemical shift between the two forms, and multiple resonances were observed for several residues. This implies a change in conformation and the existence of multiple conformations of the domain on reductive acetylation, which may be important in stabilizing this catalytic intermediate.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Publisher: American Chemical Society
ISSN: 0006-2960
Last Modified: 09 Nov 2022 10:23

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