Thomson C J, Young H K, Amyes S G
Department of Medical Microbiology, Medical School, University of Edinburgh.
J Med Microbiol. 1993 Apr;38(4):250-5. doi: 10.1099/00222615-38-4-250.
Hyperproduction of the type IV plasmid-encoded dihydrofolate reductase was studied in Escherichia coli J62-2 (pUK1123). Hyperproduction of the enzyme was shown to occur not simply as a response to a given concentration of trimethoprim but also to the presence of thymidine in the medium. Before hyperproduction occurred the bacteria began to elongate and die, thus showing the symptoms of thymine starvation. Hyperproduction also required the presence of L-methionine, adenine and glycine, suggesting that the elevated production of the enzyme was a response to the ability of trimethoprim to starve the cell of thymine metabolites.
对大肠杆菌J62-2（pUK1123）中IV型质粒编码的二氢叶酸还原酶的过量产生进行了研究。结果表明，该酶的过量产生不仅是对给定浓度甲氧苄啶的反应，也是对培养基中胸苷存在的反应。在过量产生之前，细菌开始伸长并死亡，从而表现出胸腺嘧啶饥饿的症状。过量产生还需要L-甲硫氨酸、腺嘌呤和甘氨酸的存在，这表明该酶产量的提高是对甲氧苄啶使细胞缺乏胸腺嘧啶代谢物能力的一种反应。
