Circadian Input Kinases and Their Homologs in Cyanobacteria: Evolutionary Constraints Versus Architectural Diversification
Circadian Input Kinases and Their Homologs in Cyanobacteria: Evolutionary Constraints Versus Architectural Diversification
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DOI：
10.1007/s00239-010-9344-0
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发表时间：
2010-05-01
影响因子：
3.9
通讯作者：
Dvornyk, Volodymyr
中科院分区：
文献类型：
--
作者：
Baca, Ivan;Sprockett, Daniel;Dvornyk, Volodymyr
昼夜节律输入激酶 A (cikA) 基因编码一种蛋白质，可将环境信号传递至蓝细菌的中央昼夜节律振荡器。 CikA 蛋白具有可变的结构，通常由四个串联排列的结构域组成：GAF、组氨酸激酶 (HisKA)、组氨酸激酶样 ATP 酶 (HATPase_c) 和伪接收器 (REC)。其中，HisKA和HATPase_c多态性最少，异囊丝状蓝藻中不存在REC。 CikA 包含几个可能对昼夜节律功能很重要的保守基序。至少有三种类型的昼夜节律系统，每种类型都拥有一组不同的昼夜节律基因。最初描述的昼夜节律系统（kaiABC系统）同时具有cikA和kaiA，而其他系统要么仅缺少cikA（kaiABC（Delta））或两者（kaiBC）。我们获得的结果使我们能够估计 cikA 起源的时间约为 2600-2200 MYA，而具有 kaiABC (Delta) 或 kaiBC 系统的物种中 cikA 消失的时间约为 1100 至 600 MYA。与其非昼夜节律同源物相比，CikA 的昼夜节律特化是多种因素的结果，包括独特的保守域结构和某些域和区域的高度进化限制，这些域和区域先前被认为对该基因的昼夜节律功能至关重要。
The circadian input kinase A (cikA) gene encodes a protein relaying environmental signal to the central circadian oscillator in cyanobacteria. The CikA protein has a variable architecture and usually consists of four tandemly arrayed domains: GAF, histidine kinase (HisKA), histidine kinase-like ATPase (HATPase_c), and a pseudo-receiver (REC). Among them, HisKA and HATPase_c are the least polymorphic, and REC is not present in heterocystic filamentous cyanobacteria. CikA contains several conserved motifs that are likely important for circadian function. There are at least three types of circadian systems, each of which possesses a different set of circadian genes. The originally described circadian system (kaiABC system) possesses both cikA and kaiA, while the others lack either only cikA (kaiABC (Delta)) or both (kaiBC). The results we obtained allowed us to approximate the time of the cikA origin to be about 2600-2200 MYA and the time of its loss in the species with the kaiABC (Delta) or kaiBC system between 1100 and 600 MYA. Circadian specialization of CikA, as opposed to its non-circadian homologs, is a result of several factors, including the unique conserved domain architecture and high evolutionary constraints of some domains and regions, which were previously identified as critical for the circadian function of the gene.