Studies on the inhibition by alpha-amanitin of single-step addition reactions and productive RNA synthesis catalysed by wheat-germ RNA polymerase II.
Studies on the inhibition by alpha-amanitin of single-step addition reactions and productive RNA synthesis catalysed by wheat-germ RNA polymerase II.
复制标题
α-鹅膏蕈碱对小麦胚芽 RNA 聚合酶 II 催化的单步加成反应和生产性 RNA 合成的抑制研究。
作者：
L. D. Mercoyrol;C. Job;D. Job
在 α-鹅膏蕈碱存在下，与 UTP 底物、U-A 引物、聚[d(A-T)]模板和麦芽 RNA 聚合酶 II 形成单磷酸二酯键的速率大大降低。半最大抑制发生在 0.04 微克/毫升，与高等植物物种 II 类 RNA 聚合酶抑制生产性 RNA 合成的已发表值非常一致。然而，很大一部分 U-A-U 合成能够抵抗过量 α-鹅膏蕈碱的抑制。在额外存在 ATP 的情况下，即在允许 RNA 链延长的实验条件下，聚[r(A-U)]的合成在第一个磷酸二酯键形成后被抑制。结果支持这样的论点：α-鹅膏蕈碱破坏的主要酶过程是转录复合物沿着 DNA 模板的易位步骤。
The rate of formation of a single phosphodiester bond with UTP substrate, U-A primer, poly[d(A-T)] template and wheat-germ RNA polymerase II is greatly depressed in the presence of alpha-amanitin. Half-maximal inhibition occurs at 0.04 microgram/ml, in close agreement with published values for inhibition of productive RNA synthesis with class II RNA polymerases from higher-plant species. However, a sizeable proportion of U-A-U synthesis is resistant to inhibition by excess alpha-amanitin. In the additional presence of ATP, i.e. under experimental conditions permitting RNA chain elongation, the synthesis of poly[r(A-U)] is arrested after the formation of the first phosphodiester bond. The results support the contention that the main enzymic process disrupted by alpha-amanitin is the translocation step of the transcription complex along the DNA template.