5c4r

CobK precorrin-6A reductase

spinqualitylabelsall models 5c4r, resolution 3.17Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5c4r is a 1 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Activity: Precorrin-6A reductase, with EC number 1.3.1.54 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [COBK_RHOCB] Catalyzes the reduction of the macrocycle of precorrin-6X into precorrin-6Y. Publication Abstract from PubMed CobK catalyzes the essential reduction of the precorrin ring in the cobalamin biosynthetic pathway. The crystal structure of CobK reveals that the enzyme, despite not having the signature sequence, comprises two Rossmann fold domains which bind coenzyme and substrate respectively. The two parallel beta-sheets have swapped their last beta-strands giving a novel sheet topology which is an interesting variation on the Rossmann-fold. The trapped ternary complex with coenzyme and product reveals five conserved basic residues that bind the carboxylates of the tetrapyrrole tightly anchoring the product. A loop, disordered in both the apoenzyme and holoenzyme structures, closes around the product further tightening binding. The structure is consistent with a mechanism involving protonation of C18 and pro-R hydride transfer from NADPH to C19 of precorrin-6A and reveals the interactions responsible for the specificity of CobK. The almost complete burial of the reduced precorrin product suggests a remarkable form of metabolite channeling where the next enzyme in the biosynthetic pathway triggers product release. Crystal structure of CobK reveals strand-swapping between Rossmann-fold domains and molecular basis of the reduced precorrin product trap.,Gu S, Sushko O, Deery E, Warren MJ, Pickersgill RW Sci Rep. 2015 Nov 30;5:16943. doi: 10.1038/srep16943. PMID:26616290 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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