2hp0
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Crystal structure of iminodisuccinate epimerase
OverviewOverview
Iminodisuccinate (IDS) epimerase catalyzes the epimerisation of R,R-, S,S-, and R,S- iminodisuccinate, one step in the biodegradation of the chelating, agent iminodisuccinate by Agrobacterium tumefaciens BY6. The enzyme is a, member of the MmgE/PrpD protein family, a diverse and little characterized, class of proteins of prokaryotic and eukaryotic origin. IDS epimerase does, not show significant overall amino acid sequence similarity to any other, protein of known three-dimensional structure. The crystal structure of, this novel epimerase has been determined by multi-wavelength diffraction, to 1.5 A resolution using selenomethionine-substituted enzyme. In the, crystal, the enzyme forms a homo-dimer, and the subunit consists of two, domains. The larger domain, not consecutive in sequence and comprising, residues Met1-Lys266 and Leu400-Pro446, forms a novel all alpha-helical, fold with a central six-helical bundle. The second, smaller domain folds, into an alpha+beta domain, related in topology to chorismate mutase by a, circular permutation. IDS epimerase is thus not related in, three-dimensional structure to other known epimerases. The fold of the IDS, epimerase is representative for the whole MmgE/PrpD family. The putative, active site is located at the interface between the two domains of the, subunit, and is characterized by a positively charged surface, consistent, with the binding of a highly negatively charged substrate such as, iminodisuccinate. Docking experiments suggest a two-base mechanism for the, epimerisation reaction.
About this StructureAbout this Structure
2HP0 is a Protein complex structure of sequences from Agrobacterium tumefaciens with , and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional structure of iminodisuccinate epimerase defines the fold of the MmgE/PrpD protein family., Lohkamp B, Bauerle B, Rieger PG, Schneider G, J Mol Biol. 2006 Sep 22;362(3):555-66. Epub 2006 Jul 29. PMID:16934291
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