Shavlovskiĭ G M, Tesliar G E, Strugovshchikova L P
Mikrobiologiia. 1982 Nov-Dec;51(6):986-92.
355 Escherichia coli mutants requiring riboflavin (RF) for their growth were selected using N-methyl-N-nitro-N-nitrosoguanidine. The mutants were subdivided into four biochemical groups according to their capability to accumulate fluorescent pigments in the medium and their nature, the ability to grow in a medium containing either diacetyl or 6,7-dimethyl-8-ribityl lumazine (DMRL), and the activity of GTP cyclohydrolase II and RF synthase. The rate of RF accumulation by the parent strain of E. coli and the rate of DMRL synthesis by the mutants with blocked RF synthase were identical when the cells were grown in a medium without flavins and did not change when the cells were incubated in a medium containing rifampicin, an inhibitor of transcription. RF had no effect on the rate of DMRL accumulation in the cultural broth when the mutants belonging to the fourth biochemical group were cultivated in a medium with RF. Under the same conditions, RF did not inhibit the activities of GTP cyclohydrolase II and RF synthase in the mutants of the second biochemical group. It is supposed that the enzymes of flavinogenesis in E. coli are constitutive ones.
利用N-甲基-N-硝基-N-亚硝基胍筛选出355株生长需要核黄素（RF）的大肠杆菌突变体。根据突变体在培养基中积累荧光色素的能力及其特性、在含有双乙酰或6,7-二甲基-8-核糖基-lumazine（DMRL）的培养基中生长的能力以及GTP环水解酶II和RF合酶的活性，将这些突变体分为四个生化组。当细胞在不含黄素的培养基中生长时，大肠杆菌亲本菌株积累RF的速率与RF合酶受阻的突变体合成DMRL的速率相同，并且当细胞在含有转录抑制剂利福平的培养基中培养时，该速率不变。当属于第四生化组的突变体在含有RF的培养基中培养时，RF对培养液中DMRL的积累速率没有影响。在相同条件下，RF不抑制第二生化组突变体中GTP环水解酶II和RF合酶的活性。据推测，大肠杆菌中黄素生成的酶是组成型酶。
