Miura A, Krueger J H, Itoh S, de Boer H A, Nomura M
Cell. 1981 Sep;25(3):773-82. doi: 10.1016/0092-8674(81)90185-9.
Hybrid transducing phages were constructed in vitro that carry the galK gene fused to each of three ribosomal promoters: the promotor for an rRNA operon (rrnE); the promoter for the spec r protein operon and the promotor for the alpha r protein operon. We also constructed hybrid transducing phages that carry the IacZ gene fused to the promoter for the rrnE operon or to the promoter for the spc r protein operon. The amounts of galactokinase (or beta-galactosidase) were analyzed in lysogens carrying these various transducing phages grown in several different growth media. The synthesis rate of galactokinase (or beta-galactosidase) from the fused rrn-gal (or rrn-lac) operon relative to the total protein synthesis rate increased with increasing growth rate, as expected from the transcriptional activity of rRNA operons. In contrast, the relative synthesis rate of galactokinase (or beta-galactosidase) from the operon fused to alpha or spc r protein promoter remained approximately constant with increasing growth rate. These results were interpreted to mean that the characteristic increase in the relative synthesis rate of r protein with increasing growth rate is determined not by transcription regulatory mechanisms, but by posttranscriptional mechanisms, which presumably involve the feedback inhibition of r protein mRNA translation by free r proteins.
体外构建了携带与三个核糖体启动子之一融合的galK基因的杂交转导噬菌体：一个rRNA操纵子（rrnE）的启动子；spec r蛋白操纵子的启动子和α r蛋白操纵子的启动子。我们还构建了携带与rrnE操纵子启动子或spc r蛋白操纵子启动子融合的IacZ基因的杂交转导噬菌体。分析了在几种不同生长培养基中生长的携带这些不同转导噬菌体的溶原菌中半乳糖激酶（或β-半乳糖苷酶）的量。如rRNA操纵子的转录活性所预期的那样，随着生长速率的增加，来自融合的rrn-gal（或rrn-lac）操纵子的半乳糖激酶（或β-半乳糖苷酶）的合成速率相对于总蛋白质合成速率增加。相反，随着生长速率的增加，与α或spc r蛋白启动子融合的操纵子的半乳糖激酶（或β-半乳糖苷酶）的相对合成速率大致保持恒定。这些结果被解释为意味着r蛋白相对合成速率随生长速率增加的特征性增加不是由转录调控机制决定的，而是由转录后机制决定的，推测这涉及游离r蛋白对r蛋白mRNA翻译的反馈抑制。
