Mapping of catalytic residues in the RNA polymerase active center
Mapping of catalytic residues in the RNA polymerase active center
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DOI：
10.1126/science.273.5271.107
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发表时间：
1996-07-05
期刊：
影响因子：
56.9
通讯作者：
Mustaev, A
中科院分区：
文献类型：
--
作者：
Zaychikov, E;Martin, E;Mustaev, A
当大肠杆菌RNA聚合酶（RNAP）催化中心的Mg 2+离子被Fe 2+取代时，产生羟基自由基。在启动子复合物中，这样的自由基在转录起始位点附近切割模板DNA，而β '亚基在保守基序NADFDGD（Asn-Ala-Asp-Phe-Asp-Gly-Asp）处切割。用丙氨酸取代三个天冬氨酸残基产生显性致死突变。突变体RNAP无催化活性，但能与启动子结合形成开放复合物，不能支持Fe ~（2+）诱导的DNA或蛋白质切割。因此，NADFDGD基序参与活性中心Mg 2+的螯合。
When the Mg2+ ion in the catalytic center of Escherichia coli RNA polymerase (RNAP) is replaced with Fe2+, hydroxyl radicals are generated. In the promoter complex, such radicals cleave template DNA near the transcription start site, whereas the beta' subunit is cleaved at a conserved motif NADFDGD (Asn-Ala-Asp-Phe-Asp-Gly-Asp). Substitution of the three aspartate residues with alanine creates a dominant lethal mutation. The mutant RNAP is catalytically inactive but can bind promoters and form an open complex, The mutant fails to support Fe2+-induced cleavage of DNA or protein. Thus, the NADFDGD motif is involved in chelation of the active center Mg2+.