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2,5‐diamino‐6‐ribitylamino‐4(3 H )‐pyrimidinone 5′‐phosphate synthases of fungi and archaea
Author(s) -
RömischMargl Werner,
Eisenreich Wolfgang,
Haase Ilka,
Bacher Adelbert,
Fischer Markus
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06586.x
Subject(s) - aquifex aeolicus , stereochemistry , enzyme , biochemistry , archaea , phosphate , reductase , yeast , chemistry , biology , escherichia coli , gene
The pathway of riboflavin (vitamin B 2 ) biosynthesis is significantly different in archaea, eubacteria, fungi and plants. Specifically, the first committed intermediate, 2,5‐diamino‐6‐ribosylamino‐4(3 H )‐pyrimidinone 5′‐phosphate, can either undergo hydrolytic cleavage of the position 2 amino group by a deaminase (in plants and most eubacteria) or reduction of the ribose side chain by a reductase (in fungi and archaea). We compare 2,5‐diamino‐6‐ribitylamino‐4(3 H )‐pyrimidinone 5′‐phosphate synthases from the yeast Candida glabrata , the archaeaon Methanocaldococcus jannaschii and the eubacterium Aquifex aeolicus . All three enzymes convert 2,5‐diamino‐6‐ribosylamino‐4(3 H )‐pyrimidinone 5′‐phosphate into 2,5‐diamino‐6‐ribitylamino‐4(3 H )‐pyrimidinone 5′‐phosphate, as shown by 13 C‐NMR spectroscopy using [2,1′,2′,3′,4′,5′‐ 13 C 6 ]2,5‐diamino‐6‐ribosylamino‐4(3 H )‐pyrimidinone 5′‐phosphate as substrate. The β anomer was found to be the authentic substrate, and the α anomer could serve as substrate subsequent to spontaneous anomerisation. The M. jannaschii and C. glabrata enzymes were shown to be A‐type reductases catalysing the transfer of deuterium from the 4(R) position of NADPH to the 1′ (S) position of the substrate. These results are in agreement with the known three‐dimensional structure of the M. jannaschii enzyme.