CAJ | 학술논문

采用1-甲基-3-硝基-1-亚硝基胍基因突变法，得到大肠杆菌K-12的耐蛋氨酸类似物突变体。经过发酵测试，突变菌株获得1020 mg/L的L-蛋氨酸产量。研究结果表明：L-蛋氨酸生物合成过程中的2个关键酶，即胱硫醚γ-合酶与胱硫醚β-裂解酶，在L-蛋氨酸发酵过程中未受到蛋氨酸的反馈阻遏。采用PCR方法对突变体的MetJ蛋白克隆并进行基因测序可知，野生型的第54位的丝氨酸基因被替换为天冬氨酰，使得反馈阻遏作用消除，从而有效提高L-蛋氨酸的发酵产量。
채용1-갑기-3-초기-1-아초기고기인돌변법，득도대장간균K-12적내단안산유사물돌변체。경과발효측시，돌변균주획득1020 mg/L적L-단안산산량。연구결과표명：L-단안산생물합성과정중적2개관건매，즉광류미γ-합매여광류미β-렬해매，재L-단안산발효과정중미수도단안산적반궤조알。채용PCR방법대돌변체적MetJ단백극륭병진행기인측서가지，야생형적제54위적사안산기인피체환위천동안선，사득반궤조알작용소제，종이유효제고L-단안산적발효산량。
Gene mutation was carried out using N-methyl-N′-nitro-N-nitrosoguanidine. L-met-analogue-resistant mutants were derived from Escherichia coli K-12. The mutants produced 1 020 mg/L L-met in the fermentation test. It was confirmed that two key enzymes ,cystathionine γ-synthase and cystathionineβ-lyase were not repressed by excess of L-met during fermentation. MetJ protein was cloned and sequenced by the PCR. It was observed that serine at position 54 was replaced by asparaginate ,which enhanced L-met production because of the depression of L-met biosynthetic enzymes.