Primakoff P
J Bacteriol. 1981 Jan;145(1):410-6. doi: 10.1128/jb.145.1.410-416.1981.
Under conditions of amino acid limitation, beta-galactosidase was produced at a 70-fold higher rate in a relA+ strain than in an isogenic relA strain of Escherichia coli K-12. Under identical conditions with the relA+ and relA strains carrying various lac promoter mutations, rates of beta-galactosidase synthesis in relA+ (relative to relA) ranged from 26-fold higher (promoter mutant Pr 13) to only 5-fold higher (promoter mutant PrL8uv5). This promoter specificity was independent of strain background and the means of eliciting amino acid limitation. Addition of cyclic AMP to the growth medium altered the relA+/relA difference for beta-galactosidase synthesis from the wild-type lac promoter. The experiments suggest that the relA+/relA difference in lac expression arises primarily at the point of transcription initiation. The results are discussed in relation to recent in vitro data showing a promoter-specific guanosine 5'-diphosphate 3'-diphosphate stimulation of lac transcription (P. Primakoff and S. W. Artz, Proc. Natl. Acad. Sci. U.S.A. 76:1726-1730).
在氨基酸限制条件下，与大肠杆菌K-12的同基因relA菌株相比，relA⁺菌株中β-半乳糖苷酶的产生速率要高70倍。在携带各种乳糖启动子突变的relA⁺和relA菌株的相同条件下，relA⁺（相对于relA）中β-半乳糖苷酶的合成速率范围从高26倍（启动子突变体Pr 13）到仅高5倍（启动子突变体PrL8uv5）。这种启动子特异性与菌株背景以及引发氨基酸限制的方式无关。向生长培养基中添加环磷酸腺苷改变了野生型乳糖启动子β-半乳糖苷酶合成的relA⁺/relA差异。实验表明，lac表达中的relA⁺/relA差异主要出现在转录起始点。结合最近的体外数据讨论了这些结果，该数据显示了启动子特异性的鸟苷5'-二磷酸3'-二磷酸对lac转录的刺激作用（P. Primakoff和S. W. Artz，《美国国家科学院院刊》76:1726 - 1730）。
