4n7q | pdb_00004n7q

Crystal structure of eukaryotic THIC from A. thaliana

spinqualitylabelsall models 4n7q, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4n7q is a 1 chain structure with sequence from Arath. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CO, HEZ Gene: THIC, PY, At2g29630, T27A16.27 (ARATH) Activity: Phosphomethylpyrimidine synthase, with EC number 4.1.99.17 Resources: FirstGlance, OCA, RCSB, PDBsum Function [THIC_ARATH] Catalyzes the synthesis of the hydroxymethylpyrimidine phosphate (HMP-P) moiety of thiamine from aminoimidazole ribotide (AIR) in a radical S-adenosyl-L-methionine (SAM)-dependent reaction. Publication Abstract from PubMed Vitamin B1 is an essential compound in all organisms acting as a cofactor in key metabolic reactions. It is formed by the condensation of two independently biosynthesized molecules referred to as the pyrimidine and thiazole moieties. In bacteria and plants, the biosynthesis of the pyrimidine moiety, 4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate (HMP-P), requires a single enzyme, THIC (HMP-P synthase). The enzyme uses an iron-sulfur cluster as well as a 5'-deoxyadenosyl radical as cofactors to rearrange the 5-amino-imidazole ribonucleotide (AIR) substrate to the pyrimidine ring. So far, the only structure reported is the one from the bacteria Caulobacter crescentus. In an attempt to structurally characterize an eukaryotic HMP-P synthase, we have determined the high-resolution crystal structure of THIC from Arabidopsis thaliana at 1.6A. The structure is highly similar to its bacterial counterpart although several loop regions show significant differences with potential implications for the enzymatic properties. Furthermore, we have found a metal ion with octahedral coordination at the same location as a zinc ion in the bacterial enzyme. Our high-resolution atomic model shows a metal ion with multiple coordinated water molecules in the close vicinity of the substrate binding sites and is an important step toward the full characterization of the chemical rearrangement occurring during HMP-P biosynthesis. High-resolution crystal structure of the eukaryotic HMP-P synthase (THIC) from Arabidopsis thaliana.,Coquille S, Roux C, Mehta A, Begley TP, Fitzpatrick TB, Thore S J Struct Biol. 2013 Oct 23. pii: S1047-8477(13)00270-0. doi:, 10.1016/j.jsb.2013.10.005. PMID:24161603 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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