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'''THE CRYSTAL STRUCTURE OF ADP-L-GLYCERO-D-MANNOHEPTOSE 6-EPIMERASE''' | '''THE CRYSTAL STRUCTURE OF ADP-L-GLYCERO-D-MANNOHEPTOSE 6-EPIMERASE''' | ||
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[[Category: Jr., W G.Coleman.]] | [[Category: Jr., W G.Coleman.]] | ||
[[Category: Ni, Y S.]] | [[Category: Ni, Y S.]] | ||
[[Category: | [[Category: C-terminal mixed alpha/beta domain]] | ||
[[Category: | [[Category: N-terminal domain rossmann fold]] | ||
[[Category: | [[Category: Short-chain dehydrogenase/reductase fold]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:23:39 2008'' | |||
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Revision as of 15:23, 2 May 2008
THE CRYSTAL STRUCTURE OF ADP-L-GLYCERO-D-MANNOHEPTOSE 6-EPIMERASE
OverviewOverview
BACKGROUND: ADP-L-glycero--mannoheptose 6-epimerase (AGME) is required for lipopolysaccharide (LPS) biosynthesis in most genera of pathogenic and non-pathogenic Gram-negative bacteria. It catalyzes the interconversion of ADP-D-glycero-D-mannoheptose and ADP-L-glycero-D-mannoheptose, a precursor of the seven-carbon sugar L-glycero-mannoheptose (heptose). Heptose is an obligatory component of the LPS core domain; its absence results in a truncated LPS structure resulting in susceptibility to hydrophobic antibiotics. Heptose is not found in mammalian cells, thus its biosynthetic pathway in bacteria presents a unique target for the design of novel antimicrobial agents. RESULTS: The structure of AGME, in complex with NADP and the catalytic inhibitor ADP-glucose, has been determined at 2.0 A resolution by multiwavelength anomalous diffraction (MAD) phasing methods. AGME is a homopentameric enzyme, which crystallizes with two pentamers in the asymmetric unit. The location of 70 crystallographically independent selenium sites was a key step in the structure determination process. Each monomer comprises two domains: a large N-terminal domain, consisting of a modified seven-stranded Rossmann fold that is associated with NADP binding; and a smaller alpha/beta C-terminal domain involved in substrate binding. CONCLUSIONS: The first structure of an LPS core biosynthetic enzyme leads to an understanding of the mechanism of the conversion between ADP-D-glycero--mannoheptose and ADP-L-glycero-D-mannoheptose. On the basis of its high structural similarity to UDP-galactose epimerase and the three-dimensional positions of the conserved residues Ser116, Tyr140 and Lys144, AGME was classified as a member of the short-chain dehydrogenase/reductase (SDR) superfamily. This study should prove useful in the design of mechanistic and structure-based inhibitors of the AGME catalyzed reaction.
About this StructureAbout this Structure
1EQ2 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of ADP-L-glycero-D-mannoheptose 6-epimerase: catalysis with a twist., Deacon AM, Ni YS, Coleman WG Jr, Ealick SE, Structure. 2000 May 15;8(5):453-62. PMID:10896473 Page seeded by OCA on Fri May 2 15:23:39 2008