De Felice M, Squires C, Levinthal M, Guardiola J, Lamberti A, Iaccarino M
Mol Gen Genet. 1977 Nov 4;156(1):1-7. doi: 10.1007/BF00272245.
We studied the production of the ilvG gene product, the valine resistant acetolactate synthase isoenzyme II, in an ilvO+ G+ ilvB ilvHI derivative of Escherichia coli K-12. This strain contains mutations in the structural genes for the valine sensitive acetolactate synthase isoenzymes I and III. We find that the ilvG gene is not expressed in this strain when gworn with either isoleucine and valine or with isoleucine, leucine and valine, or when limited for either isoleucine or valine. Since we previously found that the ilvG gene is expressed in an ilvO603 containing strain (Favre et al., 1976), we presume that the mechanism by which E. coli K-12 regulates the ilv gene cluster is responsible for the lack of ilvG expression in the ilvO+ strain. The valine sensitivity of E. Coli K-12 is a consequence of this regulatory pattern.
我们研究了在大肠杆菌K-12的ilvO⁺ G⁺ ilvB ilvHI衍生物中ilvG基因产物（抗缬氨酸乙酰乳酸合酶同工酶II）的产生。该菌株在缬氨酸敏感的乙酰乳酸合酶同工酶I和III的结构基因中含有突变。我们发现，当该菌株与异亮氨酸和缬氨酸一起培养，或与异亮氨酸、亮氨酸和缬氨酸一起培养时，或者当异亮氨酸或缬氨酸受限的情况下，ilvG基因在该菌株中不表达。由于我们之前发现ilvG基因在含有ilvO603的菌株中表达（法夫尔等人，1976年），我们推测大肠杆菌K-12调节ilv基因簇的机制是导致ilvO⁺菌株中ilvG缺乏表达的原因。大肠杆菌K-12对缬氨酸的敏感性是这种调节模式的结果。
