Caster J H, Melechen N E
J Bacteriol. 1968 May;95(5):1835-43. doi: 10.1128/jb.95.5.1835-1843.1968.
Inhibitors of protein synthesis do not consistently prevent formation of the lac operon repressor, according to several published reports, although direct evidence indicates that the repressor is a protein. Inhibition of ribonucleic acid (RNA) synthesis has never been shown to block lactose repression. These results have raised the possibility that repressor is synthesized in some unusual fashion. We have studied the effect of various inhibitors upon the establishment of repression in zygotes, utilizing conditions which minimize catabolite repression. Inhibition of protein synthesis by either chloramphenicol treatment or tryptophan deprivation blocked repressor formation in our experiments. Sodium borate and 6-azauracil are compounds reported to be specific inhibitors of RNA synthesis, and their behavior in control experiments is consistent with this specificity. Both delayed the establishment of repression. Thymine deprivation, either by starvation of a thymine auxotroph or by treatment with 5-fluorodeoxyuridine, did not delay the onset of repression. We conclude that repressor formation requires RNA synthesis and probably utilizes the usual protein-forming mechanisms.
根据几篇已发表的报告，蛋白质合成抑制剂并不能始终如一地阻止乳糖操纵子阻遏物的形成，尽管直接证据表明阻遏物是一种蛋白质。从未有研究表明抑制核糖核酸（RNA）合成会阻碍乳糖阻遏作用。这些结果增加了阻遏物以某种不寻常方式合成的可能性。我们利用将分解代谢物阻遏降至最低的条件，研究了各种抑制剂对合子中阻遏作用建立的影响。在我们的实验中，氯霉素处理或色氨酸剥夺对蛋白质合成的抑制作用均会阻止阻遏物的形成。硼酸钠和6-氮尿嘧啶是据报道的RNA合成特异性抑制剂，它们在对照实验中的表现与这种特异性相符。两者均延迟了阻遏作用的建立。通过胸腺嘧啶营养缺陷型菌株饥饿培养或用5-氟脱氧尿苷处理来剥夺胸腺嘧啶，并未延迟阻遏作用的开始。我们得出结论，阻遏物的形成需要RNA合成，并且可能利用通常的蛋白质形成机制。
