[经2,2,6,6-四甲基-4-溴乙酰氧基哌啶-1-氧基修饰的T2 DNA作为大肠杆菌B RNA聚合酶的模板]

[T2 DNA, modified by 2,2,6,6-tetramethyl-4-bromoacetooxypiperidine-i-oxyl as a template for RNA polymerase from E. coli B].

作者信息

Kamzolova S G, Artiukh R I, Elfimova L I

出版信息

Biokhimiia. 1977 Jun;42(6):1117-22.

Abstract

T2-DNA was modified by 2,2,6,6-tetramethyl-4-bromoacetooxypiperidine-1-oxyl (I) at different NaCl concentrations (10(-1) M NaCl--10(-4) M NaCl). Modified DNA were investigated as templates for the RNA-polymerase from E. coli B. It was shown that T2-DNA modified I in 0,1 M NaCl completely preserves the native secondary structure, has a low degree modification (1 molecule I per 1000-2000 nucleotide pairs), but is a noneffective template for the RNA-polymerase from E. coli B (20%-40% as compared with unmodified T2-DNA). Under these conditions the modification occurs probably at the "weakest" (readily melting) sites of DNA. The role of these "weak" sites on DNA as promotors is discussed. The modification of T2-DNA by reagnet I has a stronger inhibitory effect on the total RNA synthesis than on the RNA-synthesis stable to rifampicin. Possible existence of two kinds of "early" promotors on T2-DNA is assumed.

摘要

在不同氯化钠浓度（10⁻¹M氯化钠 - 10⁻⁴M氯化钠）下，用2,2,6,6 - 四甲基 - 4 - 溴乙酰氧基哌啶 - 1 - 氧基（I）对T2 - DNA进行修饰。将修饰后的DNA作为大肠杆菌B的RNA聚合酶的模板进行研究。结果表明，在0.1M氯化钠中用I修饰的T2 - DNA完全保留了天然二级结构，修饰程度较低（每1000 - 2000个核苷酸对中有1个I分子），但对于大肠杆菌B的RNA聚合酶而言是无效模板（与未修饰的T2 - DNA相比为20% - 40%）。在这些条件下，修饰可能发生在DNA的“最弱”（最易解链）位点。讨论了这些DNA上“弱”位点作为启动子的作用。试剂I对T2 - DNA的修饰对总RNA合成的抑制作用比对利福平稳定的RNA合成的抑制作用更强。假定T2 - DNA上可能存在两种“早期”启动子。