Electron microscopic studies of the binding of Escherichia coli RNA polymerase to DNA. I. Characterization of the non-specific interactions of holoenzyme with a restriction fragment of bacteriophage T7 DNA.
Electron microscopic studies of the binding of Escherichia coli RNA polymerase to DNA. I. Characterization of the non-specific interactions of holoenzyme with a restriction fragment of bacteriophage T7 DNA.
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大肠杆菌 RNA 聚合酶与 DNA 结合的电子显微镜研究。
DOI：
10.1016/0022-2836(80)90366-6
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发表时间：
1980
影响因子：
5.6
通讯作者：
M. Chamberlin
中科院分区：
文献类型：
--
作者：
T. Kadesch;R. Williams;M. Chamberlin
用电子显微镜观察了噬菌体T7 DNA的3800个碱基对限制性片段(MBOI-C)与大肠杆菌RNA聚合酶全酶的非特异性相互作用。全酶与DNA的结合相对较弱且快速可逆，在盐浓度升高时仅略有减少。当NaC l浓度从50 mM增加到200 mM时，结合常数从2×104M−1下降到4×103M−1。结论是，当全酶非特异性结合时，只有1~2个钠离子从DNA中释放出来。
Non-specific interactions between a 3800 base-pair restriction fragment of bacteriophage T7 DNA (MboI-C) andEscherichia coliRNA polymerase holoenzyme have been examined by electron microscopy. Holoenzyme displays a relatively weak and rapidly reversible binding to DNA that is only slightly reduced at elevated salt concentrations. As the concentration of NaCl is increased from 50 mmto 200 mm, the binding constant decreases from 2 × 104m−1to 4 × 103m−1. It is concluded that only 1 to 2 sodium ions are released from the DNA when holoenzyme binds non-specifically.The validity of the electron microscopic technique for determining binding constants has been investigated by varying aspects of the grid surface and by examining the non-specific interactions oflacrepressor with DNA.