Frenkel G D, Randles K
J Biol Chem. 1982 Jun 10;257(11):6275-9.
Methyl mercury has previously been shown to inhibit DNA and RNA synthesis in intact HeLa cells (Gruenwedel, D. W., and Cruikshank, M. K. (1979) Biochem. Pharmacol. 28, 651-655). Its effect on nucleic acid synthesis in vitro in isolated nuclei has now been investigated. DNA synthesis in nuclei was inhibited by methyl mercury; 50% inhibition was obtained with a concentration of 8 microM, compared to approximately 30 microM which is required in vivo. In contrast, RNA synthesis in HeLa nuclei was stimulated by methyl mercury. This stimulation is specific for alpha-amanitin-sensitive RNA synthesis (catalyzed by RNA polymerase II); in contrast, alpha-amanitin-resistant synthesis (catalyzed by polymerases I and III) was inhibited. Transcription of calf thymus DNA by solubilized RNA polymerases was inhibited by ethyl mercury. However, if the enzymes were preincubated with the DNA prior to addition of the methyl mercury, subsequent synthesis by RNA polymerase II was stimulated, whereas the inhibition of the other enzymes was unaffected. The most likely explanation for these results is that methyl mercury specifically stimulates chain elongation by RNA polymerase II whereas it inhibits elongation by polymerases I and III, and initiation by all three enzymes.
先前已表明甲基汞可抑制完整海拉细胞中的DNA和RNA合成（格鲁恩维德尔，D. W.，和克鲁克尚克，M. K.（1979年）《生物化学与药理学》28卷，651 - 655页）。现在已经研究了其对分离细胞核体外核酸合成的影响。甲基汞抑制细胞核中的DNA合成；浓度为8微摩尔时可达到50%的抑制率，而体内所需浓度约为30微摩尔。相比之下，甲基汞刺激海拉细胞核中的RNA合成。这种刺激对α - 鹅膏蕈碱敏感的RNA合成（由RNA聚合酶II催化）具有特异性；相反，α - 鹅膏蕈碱抗性合成（由聚合酶I和III催化）受到抑制。溶解的RNA聚合酶对小牛胸腺DNA的转录受到乙基汞的抑制。然而，如果在添加甲基汞之前将酶与DNA预孵育，随后RNA聚合酶II的合成会受到刺激，而其他酶的抑制作用不受影响。对这些结果最可能的解释是，甲基汞特异性地刺激RNA聚合酶II的链延伸，而抑制聚合酶I和III的延伸以及所有三种酶的起始。
