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- Title
2,5-diamino-6-ribitylamino-4(3 H)-pyrimidinone 5′-phosphate synthases of fungi and archaea.
- Authors
Römisch-Margl, Werner; Eisenreich, Wolfgang; Haase, Ilka; Bacher, Adelbert; Fischer, Markus
- Abstract
The pathway of riboflavin (vitamin B2) 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 13C-NMR spectroscopy using [2,1′,2′,3′,4′,5′-13C6]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.
- Subjects
BIOSYNTHESIS; VITAMIN B2; ARCHAEBACTERIA; EUBACTERIALES; FUNGI; PLANTS
- Publication
FEBS Journal, 2008, Vol 275, Issue 17, p4403
- ISSN
1742-464X
- Publication type
Article
- DOI
10.1111/j.1742-4658.2008.06586.x