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The structure of L-ribulose-5-phosphate 4-epimerase: An aldolase-like platform for epimerization

TitleThe structure of L-ribulose-5-phosphate 4-epimerase: An aldolase-like platform for epimerization
Publication TypeJournal Article
Year of Publication2001
AuthorsLuo, Y, Samuel, J, Mosimann, SC, Lee, JE, Tanner, ME, Strynadka, NCJ
JournalBiochemistry
Volume40
Pagination14763-14771
Date PublishedDec
Type of ArticleArticle
ISBN Number0006-2960
KeywordsCHEMISTRY, CLASS-II, CLEAVAGE, ENZYME, ESCHERICHIA-COLI, EVOLUTION, GALACTOSE, L-FUCULOSE-1-PHOSPHATE ALDOLASE, MECHANISM, SEQUENCE, SUPERFAMILIES
Abstract

The structure of L-ribulose-5 -phosphate 4-epimerase from E. coli has been solved to 2.4 Angstrom resolution using X-ray diffraction data. The structure is homo-tetrameric and displays C-4 symmetry. Each subunit has a single domain comprised of a central beta -sheet flanked on either side by layers of alpha -helices. The active site is identified by the position of the catalytic zinc residue and is located at the interface between two adjacent subunits. A remarkable feature of the structure is that it shows a very close resemblance to that of L-fuculose-1-phosphate aldolase. This is consistent with the notion that both enzymes belong to a superfamily of epimerases/aldolases that catalyze carbon-carbon bond cleavage reactions via a metal-stabilized enolate intermediate. Detailed inspection of the epimerase structure, however, indicates that despite the close overall structural similarity to class II aldolases, the enzyme has evolved distinct active site features that promote its particular chemistry.

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