Leucine-regulated self-association of leucine-responsive regulatory protein (Lrp) from Escherichia coli
Leucine-regulated self-association of leucine-responsive regulatory protein (Lrp) from Escherichia coli
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DOI：
10.1006/jmbi.2001.4955
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发表时间：
2001-09-28
影响因子：
5.6
通讯作者：
Calvo, JM
中科院分区：
文献类型：
--
作者：
Chen, S;Rosner, MH;Calvo, JM
Lrp是大肠杆菌中的一种全局调节蛋白，其激活十几个操纵子的表达并抑制另外十几个操纵子的表达。对于某些操纵子，外源亮氨酸降低Lrp作用的程度，对于其他操纵子，它增强Lrp的作用，而对于其他操纵子，它没有作用。在努力了解亮氨酸如何影响Lrp介导的表达，我们研究了Lrp的自我协会和亮氨酸的自我协会使用光散射，化学交联，和分析ultracentravation的效果。获得了以下结果。(i)Lrp自缔合十六聚体和八聚体，其中主要种类是μ M浓度的十六聚体。(ii)Lrp经历亮氨酸诱导的十六聚体解离为八聚体。(iii)在C末端缺少11个氨基酸残基的突变体Lrp不形成更高阶的寡聚体，这表明C末端参与亚基缔合。(iv)在nM浓度下，Lrp解离成二聚体。有人提出，亮氨酸调节Lrp寡聚体之间的平衡，从而Lrp占用不同操纵子内的网站，导致不同的监管模式。(C)北京：科学出版社.
Lrp is a global regulatory protein in Escherichia coli that activates expression of more than a dozen operons and represses expression of another dozen. For some operons, exogenous leucine reduces the extent of Lrp action, for others it potentiates the effect of Lrp, and for yet other operons it has no effect. In an effort to understand how leucine affects Lrp-mediated expression, we examined Lrp self-association and the effect of leucine on self-association using light scattering, chemical cross-linking, and analytical ultracentrifugation. The following results were obtained. (i) Lrp self-associates to a hexadecamer and octamer with the predominant species being hexadecamer at muM concentrations. (ii) Lrp undergoes a leucine-induced dissociation of hexadecamer to octamer. (iii) A mutant Lrp lacking 11 amino acid residues at the C terminus does not form higher-order oligomers, suggesting that the C terminus is involved in subunit association. (iv) At nM concentrations, Lrp dissociates to a dimer. It is proposed that leucine regulates the equilibrium between Lrp oligomers and thus Lrp occupancy of sites within different operons, leading to diverse regulatory patterns. (C) 2001 Academic Press.