Four-CarbonMoiety重点.PDFVIP

JOURNAL OF BACTERIOLOGY, June 1985, p. 1280-1284 Vol. 162, No. 3 0021-9193/85/061280-05$02.00/0 Copyright C 1985, American Society for Microbiology Biosynthesis of Riboflavin in Bacillus subtilis: Origin of the Four-Carbon Moiety QUANG LE VAN, PAUL J. KELLER,2 DAVID H. BOWN,2 HEINZ G. FLOSS,2* AND ADELBERT BACHER Lehrstuhlffur Organische Chemie und Biochemie, Technische Universitat Munchen, D-8046 Garching, Federal Republic of Germany, and Department of Chemistry, Ohio State University, Columbus, Ohio 432102 Received 3 January 1985/Accepted 20 March 1985 We studied the incorporation of [l-3C]ribose and [1,3-13CC2glycerol into the riboflavin precursor 6,7- dimethyl-8-ribityllumazine, using a riboflavin-deficient mutant of Bacillus subtilis. The formation of the pyrazine ring requires the addition of a four-carbon moiety to a pyrimidine precursor. The results show that C-6a, C-6, C-7, and C-7a of 6,7-dimethyl-8-ribityllumazine were biosynthetically equivalent to C-1, C-2, C-3, and C-5 of a pentose phosphate. C-4 of the pentose precursor was lost through an intramolecular skeletal rearrangement. Thus, the last steps in the biosynthesis of D o 6,7-dimethyl-8-ribityllumazine apparently involve the same mechanism in bacteria as in fungi. w