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J. Biol. Chem., Vol. 279, Issue 35, 36299-36308, August 27, 2004
Evolution of Vitamin B2 BiosynthesisSTRUCTURAL AND FUNCTIONAL SIMILARITY BETWEEN PYRIMIDINE DEAMINASES OF EUBACTERIAL AND PLANT ORIGIN*![]() From the Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, Garching D-85747, Germany The Arabidopsis thaliana open reading frame At4g20960 predicts a protein whose N-terminal part is similar to the eubacterial 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate deaminase domain. A synthetic open reading frame specifying a pseudomature form of the plant enzyme directed the synthesis of a recombinant protein which was purified to apparent homogeneity and was shown by NMR spectroscopy to convert 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate into 5-amino-6-ribosylamino-2,4(1H,3H)-pyrimidinedione 5'-phosphate at a rate of 0.9 µmol mg1 min1. The substrate and product of the enzyme are both subject to spontaneous anomerization of the ribosyl side chain as shown by 13C NMR spectroscopy. The protein contains 1 eq of Zn2+/subunit. The deaminase activity could be assigned to the N-terminal section of the plant protein. The deaminase domains of plants and eubacteria share a high degree of similarity, in contrast to deaminases from fungi. These data show that the riboflavin biosynthesis in plants proceeds by the same reaction steps as in eubacteria, whereas fungi use a different pathway.
Received for publication, April 21, 2004 , and in revised form, June 16, 2004. * This work was supported by grants from the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, and the Hans Fischer Gesellschaft. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBankTM/EBI Data Bank with accession number(s) AY456384
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