2azn | pdb_00002azn
X-RAY Structure of 2,5-diamino-6-ribosylamino-4(3h)-pyrimidinone 5-phosphate reductase
Structural highlights
FunctionRIB7_METJA Catalyzes an early step in riboflavin biosynthesis, the NAD(P)H-dependent reduction of the ribose side chain of 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate, yielding 2,5-diamino-6-ribitylamino-4(3H)-pyrimidinone 5'-phosphate. The beta anomer is the authentic substrate, and the alpha anomer can serve as substrate subsequent to spontaneous anomerization. NADPH and NADH function equally well as the reductants. Does not catalyze the reduction of 5-amino-6-(5-phospho-D-ribosylamino)uracil to 5-amino-6-(5-phospho-D-ribitylamino)uracil.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe pyrimidine reductase of the riboflavin biosynthetic pathway (MjaRED) specified by the open reading frame MJ0671 of Methanocaldococcus jannaschii was expressed in Escherichia coli using a synthetic gene. The synthetic open reading frame that was optimized for expression in E. coli directed the synthesis of abundant amounts of the enzyme with an apparent subunit mass of 25 kDa. The enzyme was purified to apparent homogeneity and was shown to catalyze the conversion of 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate into 2,5-diamino-6-ribitylamino-4(3H)-pyrimidinone 5'-phosphate at a rate of 0.8 micromol min(-1) mg(-1) at pH 8.0 and at 30 degrees C. The protein is a homodimer as shown by sedimentation equilibrium analysis and sediments at an apparent velocity of 3.5 S. The structure of the enzyme in complex with the cofactor nicotinamide adenine dinucleotide phosphate was determined by X-ray crystallography at a resolution of 2.5 Angstroms. The folding pattern resembles that of dihydrofolate reductase with the Thermotoga maritima ortholog as the most similar structure. The substrate, 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate, was modeled into the putative active site. The model suggests the transfer of the pro-R hydrogen of C-4 of NADPH to C-1' of the substrate. Biosynthesis of riboflavin: structure and properties of 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate reductase of Methanocaldococcus jannaschii.,Chatwell L, Krojer T, Fidler A, Romisch W, Eisenreich W, Bacher A, Huber R, Fischer M J Mol Biol. 2006 Jun 23;359(5):1334-51. Epub 2006 May 6. PMID:16730025[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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