SMALL ANGLE X-RAY SCATTERING OF CIRCADIAN CLOCK PROTEIN COMPLEX

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。生物钟是自我维持的生化振荡器。它们的特性包括温度补偿、大约24小时的时间常数和高精度(邓拉普等人，2004年)。这些特性很难用已知的生化反应来解释。对这些不寻常的振荡器的机制的最终解释将需要描述昼夜节律钟的分子组成的结构、功能和相互作用。我们建议了解原核生物蓝藻中生物钟的组成，在那里遗传/生化研究已经取得了成果(Ishiura等人)。1998年，Nakahira等人。2004年和约翰逊2004年)。蓝藻生物钟系统的一个耐人寻味的特征是全球基因调控--基本上生物体中的所有启动子都受昼夜节律控制。甚至异源启动子也有节奏地被导入蓝藻(Nakahira等人)。2004年)。一项突变分析发现，这个系统至少受三个必需的时钟基因的调控，它们是在染色体上形成一个簇的KaIA、Kaib和KaiC(Ishiura等人，1998)。这些基因编码的蛋白质相互作用(岩崎等人)。1999和Taniguchi等人。2001)在体内形成以KaiC为六聚体核心的大复合体。KaiC(Pattanayek等人，2003)、KaIA和Kaib的晶体结构由不同的基团知道。我们建议通过小角X射线散射来分析时钟蛋白KaIA、Kaib和KaiC在溶液中的相互作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Circadian clocks are self-sustained biochemical oscillators. Their properties include temperature compensation, a time constant of approximately 24 hr, and high precision (Dunlap et al., 2004). These properties are difficult to explain by known biochemical reactions. The ultimate explanation for the mechanism of these unusual oscillators will require characterizing the structures, functions, and interactions of the molecular components of circadian clocks. We propose to understand the components of the biological clock in the prokaryotic cyanobacteria, where genetic/biochemical studies have been productive (Ishiura et al. 1998, Nakahira et al. 2004 and Johnson2004). An intriguing feature of the circadian clock system of cyanobacteria is that of global gene regulation-essentially all the promoters in the organism are under circadian control. Even heterologous promoters are expressed rhythmically introduced into cyanobacteria (Nakahira et al. 2004). A mutational analysis discovered that this system is regulated by at least three essential clock genes, kaiA, kaiB, and kaiC, that form a cluster on the chromosome (Ishiura et al., 1998). The proteins encoded by these genes interact with each other (Iwasaki et al. 1999 and Taniguchi et al. 2001) to form large complexes in vivo in which KaiC is the hexameric core. The crystal structure of the KaiC (Pattanayek et al., 2003),KaiA and KaiB are known by different groups. We propose to analyze interactions among the clock proteins KaiA, KaiB, and KaiC in solution through small angle X-ray scattering.