E COLI PRIMASE ZINC STRUCTURE IS SENSITIVE TO BINDING OF ATP & HIGH MAGNESIUM

大肠杆菌引物酶锌结构对 ATP 结合敏感

• 批准号: 6120386
• 负责人: LINDA S POWERS
• 金额: --
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-30 至 1999-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6120386
• 关键词: bacteria; bioengineering /biomedical engineering; biological products; biomedical resource; enzymes; proteins; spectrometry

The structure of the single zinc site in primase from Escherichia coli was studied using X-ray absorption spectroscopy (XAS). The zinc site in native primase was found to be tetrahedrally ligated by three sulfurs at an average distance of 2.37 ?0.02E and one histidine nitrogen located at a distance of 2.11? 0.02 E. Addition of high concentrations of Mg ?or Mn?- acetate causes an increase in the coordination of the zinc by one or two N/O ligands so that the average N/O ligand distance is 2.19 1 0.03 E. When ssDNA was added to primase, Hthe zinc site structure also increases the coordination by one or two HN/O ligands, but the average distance is 2.05 ? 0.03 E, significantly Hdifferent from the addition of ATP which gave results within the error Hof Mg ?or Mn?-acetate. The higher shells show considerable changes Hand support a conformation change. Thus, the zinc site is altered to Hoctahedral coordination by three sulfur and three oxygen (or nitrogen) Hligands, one of which could be a histidine nitrogen. These results Hand others indicate that the primase zinc site is similar to the Hessential zinc site from Escherichia coli RNA polymerase which can Halso be coordinated by its initiating nucleotide ATP (Wu, F.Y.H., HHuang, W.J., Sinclair, R.B., Powers, L. Journal of Biological HChemistry 267: 25560-25567, 1992. In light of this, the high-magnesium conformation result suggests that high magnesium primase becomes inactive because the zinc is prevented from coordinating ATP.

大肠杆菌引发酶中单个锌位点的结构 用X射线吸收光谱法（XAS）研究了大肠杆菌的生物学特性。 锌 发现天然引发酶中位点被三个 硫的平均距离为2.37？0.02E和一个组氨酸 氮位于距离2.11？ 0.02 E.添加高 镁浓度？还是Mn？醋酸盐会导致 锌通过一个或两个N/O配体配位，使得平均 N/O配位距离为2.19 ± 0.03 E。当ssDNA加入引发酶时， 锌位结构也使配位增加了一个或两个 HN/O配体，但平均距离为2.05？0.03 E、显著 与加入ATP的结果不同， 误差霍夫镁？还是Mn？醋酸 较高的贝壳显示出相当大的 变化手支持构造变化。 因此，锌位点是 三硫三氧六配位 (or氮）H配体，其中之一可以是组氨酸氮。 这些结果和其他结果表明，引物酶锌位点是 类似于大肠杆菌RNA的H必需锌位点 也可以由其起始核苷酸配位的聚合酶 ATP（吴F.Y.H.，黄伟杰，辛克莱，R. B.，鲍尔斯湖，澳-地杂志 生物化学267：25560-25567，1992. 有鉴于此， 高镁构象结果表明，高镁 引发酶变得不活跃，因为锌被阻止， 协调ATP。