Szwajkajzer D, Dai L, Fukayama J W, Abramczyk B, Fairman R, Carey J
Chemistry Department, Princeton University, Princeton, NJ 08544-1009, USA.
J Mol Biol. 2001 Oct 5;312(5):949-62. doi: 10.1006/jmbi.2001.4941.
Allosteric activation of the hexameric arginine repressor (ArgR) for specific operator DNA binding appears to involve alteration in its quaternary structure. Current models for activation include subunit assembly and/or domain rearrangements in response to binding of the coeffector l-arginine. To investigate the molecular basis for ArgR operator interactions, we have carried out a series of quantitative analyses of ArgR subunit assembly and of the affinity, stoichiometry, cooperativity, and l-arginine- and DNA sequence-dependence of ArgR-DNA binding. The results indicate that subunit assembly plays no role in activation, although communication among subunits of the ArgR hexamer is required for specific DNA binding. The data suggest that DNA is also an allosteric effector of ArgR.
六聚体精氨酸阻遏蛋白（ArgR）对特定操纵子DNA结合的变构激活似乎涉及其四级结构的改变。当前的激活模型包括亚基组装和/或响应辅效应物L-精氨酸结合的结构域重排。为了研究ArgR与操纵子相互作用的分子基础，我们对ArgR亚基组装以及ArgR-DNA结合的亲和力、化学计量、协同性以及L-精氨酸和DNA序列依赖性进行了一系列定量分析。结果表明，亚基组装在激活过程中不起作用，尽管ArgR六聚体亚基之间的通讯对于特异性DNA结合是必需的。数据表明，DNA也是ArgR的变构效应物。
