5j84
Crystal structure of L-arabinonate dehydratase in holo-form
Structural highlights
FunctionARAD_RHILW Catalyzes the dehydration of L-arabinonate to 2-dehydro-3-deoxy-L-arabinonate during L-arabinose degradation. Can also dehydrate D-galactonate and D-fuconate with good catalytic efficiency. Has weak activity with D-xylonate and D-gluconate.[1] Publication Abstract from PubMedWe present a novel crystal structure of the IlvD/EDD family enzyme, l-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii (RlArDHT, EC 4.2.1.25), which catalyzes the conversion of l-arabinonate to 2-dehydro-3-deoxy-l-arabinonate. The enzyme is a tetramer consisting of a dimer of dimers, where each monomer is composed of two domains. The active site contains a catalytically important [2Fe-2S] cluster and Mg(2+) ion and is buried between two domains, and also at the dimer interface. The active site Lys129 was found to be carbamylated. Ser480 and Thr482 were shown to be essential residues for catalysis, and the S480A mutant structure showed an unexpected open conformation in which the active site was more accessible for the substrate. This structure showed the partial binding of l-arabinonate, which allowed us to suggest that the alkoxide ion form of the Ser480 side chain functions as a base and the [2Fe-2S] cluster functions as a Lewis acid in the elimination reaction. The Crystal Structure of a Bacterial l-Arabinonate Dehydratase Contains a [2Fe-2S] Cluster.,Rahman MM, Andberg M, Thangaraj SK, Parkkinen T, Penttila M, Janis J, Koivula A, Rouvinen J, Hakulinen N ACS Chem Biol. 2017 Jul 21;12(7):1919-1927. doi: 10.1021/acschembio.7b00304. Epub, 2017 Jun 13. PMID:28574691[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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