tailieunhanh - Báo cáo khoa học: 2,5-diamino-6-ribitylamino-4(3H)-pyrimidinone 5¢-phosphate synthases of fungi and archaea

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(3H)-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). | ỊFEBS Journal 2 5-diamino-6-ribitylamino-4 3H -pyrimidinone 5 -phosphate synthases of fungi and archaea Werner Romisch-Margl1 2 Wolfgang Eisenreich1 Ilka Haase3 Adelbert Bacher1 and Markus Fischer3 1 Lehrstuhl fur Organische Chemie und Biochemie Technische Universitat Munchen Garching Germany 2 Institute of Bioinformatics and Systems Biology Helmholtz Zentrum Munchen Neuherberg Germany 3 Institute of Food Chemistry University of Hamburg Germany Keywords 2 5-diamino-6-ribitylamino-4 3H -pyrimidinone 5 -phosphate synthase archaea fungi riboflavin biosynthesis stereochemistry Correspondence M. Fischer Institut fur Lebensmittelchemie Universitat Hamburg Grindelallee 117 D-20146 Hamburg Germany Fax 49 40 428384342 Tel 49 40 428384359 E-mail Received 18 April2008 revised 21 June 2008 accepted 4 July 2008 doi 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 3H -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 3H -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 3H -pyrimidinone 5 -phosphate into 2 5-diamino-6-ribitylami-no-4 3H -pyrimidinone 5 -phosphate as shown by 13C-NMR spectroscopy using 2 1 2 3 4 5 - 13C6 2 5-diamino-6-ribosylamino-4 3H -pyrimidinone 5 -phosphate as substrate. The b anomer was found to be the authentic substrate and the a 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 .