4ehu | pdb_00004ehu

Activator of the 2-Hydroxyisocaproyl-CoA Dehydratase from Clostridium difficile with bound ADPNP

spinqualitylabelsall models 4ehu, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4ehu is a 2 chain structure with sequence from Clostridioides difficile. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, ANP, MG, NA, SF4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [HADI_CLODI] Involved in the reductive branch of L-leucine fermentation. Required for the activation of (R)-2-hydroxyisocaproyl-CoA dehydratase. The reduced activator transfers one electron to the dehydratase concomitant with hydrolysis of ATP. This protein is extremely sensitive towards oxygen. Publication Abstract from PubMed Members of the 2-hydroxyacyl-CoA dehydratase enzyme family catalyze the beta,alpha-dehydration of various CoA-esters in the fermentation of amino acids by clostridia. Abstraction of the non-acidic beta-proton of the 2-hydroxyacyl-CoA compounds is achieved by the reductive generation of ketyl radicals on the substrate, which is initiated by the transfer of an electron at low redox potentials. The highly energetic electron needed on the dehydratase is donated by a [4Fe-4S] cluster containing ATPase, termed activator. We investigated the activator of the 2-hydroxyisocaproyl-CoA dehydratase from Clostridium difficile. The activator is a homodimeric protein structurally related to acetate and sugar kinases, Hsc70 and actin, which has a [4Fe-4S] cluster bound in the dimer interface. The crystal structures of the Mg-ADP, Mg-ADPNP and nucleotide-free states of the reduced activator have been solved at 1.6 - 3.0 A resolution, allowing us to define the position of Mg2+ and water molecules in the vicinity of the nucleotides and the [4Fe-4S] cluster. The structures reveal redox- and nucleotide dependent changes agreeing with the modulation of the reduction potential of the [4Fe-4S] cluster by conformational changes. We also investigated the propensity of the activator to form a complex with its cognate dehydratase in the presence of Mg-ADP and Mg-ADPNP and together with the structural data present a refined mechanistic scheme for the ATP-dependent electron transfer between activator and dehydratase. On the ATP-dependent Activation of the Radical Enzyme (R)-2-Hydroxyisocaproyl-CoA Dehydratase.,Knauer SH, Buckel W, Dobbek H Biochemistry. 2012 Jul 24. PMID:22827463 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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