AMINO-ACID 55 PLAYS A CENTRAL ROLE IN TETRAMERIZATION AND FUNCTION OF ESCHERICHIA-COLI SINGLE-STRANDED-DNA BINDING-PROTEIN
AMINO-ACID 55 PLAYS A CENTRAL ROLE IN TETRAMERIZATION AND FUNCTION OF ESCHERICHIA-COLI SINGLE-STRANDED-DNA BINDING-PROTEIN
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DOI：
10.1111/j.1432-1033.1991.tb15789.x
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发表时间：
1991-02-26
期刊：
影响因子：
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通讯作者：
MAASS, G
中科院分区：
文献类型：
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作者：
CURTH, U;BAYER, I;MAASS, G
大肠杆菌单链DNA结合蛋白的氨基酸序列的第55位的组氨酸被酪氨酸、谷氨酸、赖氨酸、苯丙氨酸和异亮氨酸取代。 突变蛋白质的性质进行了测定，使用分析超离心，NMR光谱，凝胶过滤，和荧光检测其单链DNA结合能力。 虽然苯丙氨酸和异亮氨酸取代没有改变蛋白质的性质可测量的，酪氨酸和赖氨酸突变体解离成亚基和松散的聚（dT）的一些结合亲和力。 对于赖氨酸突变体，我们通过电子显微镜显示，该蛋白质，虽然完全解离，并可能在自由状态下变性，结合到聚（dT）作为一个四聚体从野生型蛋白难以区分。 通过单链DNA结合能力观察到的四聚化过程由时间范围从几毫秒到几小时的各种步骤组成;它可能涉及几种形式的解离和非天然蛋白质。
The histidine at position 55 of the amino acid sequence of the Escherichia coli single-stranded DNA binding protein was replaced by tyrosine, glutamic acid, lysine, phenylalanine, and isoleucine. The properties of the mutant proteins were determined using analytical ultracentrifugation, NMR spectroscopy, gel filtration, and fluorimetric detection of their single-stranded DNA binding ability. While the phenylalanine and isoleucine substitutions did not change the properties of the protein measurably, tyrosine and lysine mutants dissociate into subunits and loose some of their binding affinity for poly(dT). For the lysine mutant we show by electron microscopy that the protein, although fully dissociated and possibly denatured in the free state, binds to poly(dT) as a tetramer indistinguishable from the wild-type protein. The process of tetramerization as observed via single-stranded DNA binding ability is composed of a variety of steps ranging in time from some milliseconds to several hours; it probably involves several forms of dissociated and non-native protein.