Lee C Y, O'Kane D J, Meighen E A
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
J Bacteriol. 1994 Apr;176(7):2100-4. doi: 10.1128/jb.176.7.2100-2104.1994.
Four genes immediately downstream of luxG in the Photobacterium phosphoreum lux operon (ribEBHA) have been sequenced and shown to be involved in riboflavin synthesis. Sequence analyses and complementation of Escherichia coli riboflavin auxotrophs showed that the gene products of ribB and ribA are 3,4-dihydroxy-2-butanone 4-phosphate (DHBP) synthetase and GTP cyclohydrolase II, respectively. By expression of P. phosphoreum ribE in E. coli using the bacteriophage T7 promoter-RNA polymerase system, ribE was shown to code for riboflavin synthetase, which catalyzes the conversion of lumazine to riboflavin. Increased thermal stability of RibE on expression with RibH indicated that ribH coded for lumazine synthetase. The organization of the rib genes in P. phosphoreum is quite distinct, with ribB and ribA being linked but separated by ribH, whereas in E. coli, they are unlinked and in Bacillus subtilis, RibB and RibA functions are coded by a single gene.
对磷光发光杆菌lux操纵子（ribEBHA）中luxG下游紧邻的四个基因进行了测序，并表明它们参与核黄素的合成。对大肠杆菌核黄素营养缺陷型的序列分析和互补实验表明，ribB和ribA的基因产物分别是3,4 - 二羟基 - 2 - 丁酮4 - 磷酸（DHBP）合成酶和GTP环化水解酶II。通过使用噬菌体T7启动子 - RNA聚合酶系统在大肠杆菌中表达磷光发光杆菌的ribE，结果表明ribE编码核黄素合成酶，该酶催化鲁米诺嗪转化为核黄素。RibE与RibH共同表达时热稳定性增加，这表明ribH编码鲁米诺嗪合成酶。磷光发光杆菌中rib基因的组织方式非常独特，ribB和ribA相连但被ribH隔开，而在大肠杆菌中它们不相连，在枯草芽孢杆菌中，RibB和RibA的功能由单个基因编码。
