CRYSTALLOGRAPHIC STUDIES OF SIGMA70 SUBUNIT OF E COLI RNA POLYMERASE

SIR提供L-特罗蛋氨酸；1.5G我们的长期目标是 了解转录的机制及其调控。 核糖核酸聚合酶(RNAP)结构的测定 负责RNA合成，是迈向这一目标的关键一步。 这最好是用高度特征化的埃希里希菌实现的 ColiRNAP。这一点尤其正确，因为 从细菌到人类的RNAP结构和机制的保守。 我们战略的一部分是确定高分辨率X射线 RNAP组件的结构。我们想用同样的方法 我们用来制备硒硫氨酸蛋白来制备蛋氨酸。 取代蛋白。这可以在两个方面帮助我们：1)如果 Boles等人的结果。(自然结构生物学1：283-284,1994)是 一般情况下，只用埋藏的蛋氨酸残基代替 在最终产品中，这可能会减少 我们蛋白质中的位点，使得解决这些位点成为可能 Boles等人的研究结果。不是一般的，我们获得蛋白质 在10个位置用硫代蛋氨酸取代，较大的同象 来自碲的信号(因为质子的数量较多)将 可能会让我们为这些网站解决问题。

The SIR provided L-Telluromethionine; 1.5g Our long term goal is to understand the mechanism of transcription and its regulation. Determining the structure of RNA polymerase (RNAP), the enzyme responsible for RNA synthesis, is an essential step towards this goal. This is best accomplished with the highly characterized Escherichia coli RNAP. This is especially true because of the remarkable degree of conservation of RNAP structure and mechanism from bacteria to man. One part of our strategy is to determine high-resolution X-ray structures of RNAP components. We would like to use the same methods we use to prepare selenomthionine protein to prepare telluromethionine substituted protein. This could help us in two ways: 1) If the result of Boles et al. (Nature Structural Biology 1:283-284, 1994) is a general one in that only buried methionine residues are substituted in the final product, then this would likely reduce the number of sites in our protein, making solving for the sites possible 2) Even if the result of Boles et al. is not general and we obtain protein substituted at 10 sites with telluromethionine, the larger isomorphous signal from tellurium (because of the larger number of protons) would likely allow us to solve for the sites.