蓝藻生物钟分子机理的研究进展

Progress in Molecular Mechanisms of Circadian Clock in Cyanobacteria

蓝藻是具有内源性生物钟的简单生物.虽然蓝藻生物钟具有跟真核生物同样的基础特征,但其相关基因和蛋白质与真核生物没有同源性.蓝藻生物钟的核心是kai基因簇及其编码的蛋白KaiA,KaiB和KaiC.这三种Kai蛋白相互作用调节KaiC的磷酸化状态,从而产生昼夜节律信息.KaiC的磷酸化循环是昼夜节律的起博器,调控包括kai基因在内的相关基因的节律性表达.组氨酸蛋白激酶的磷酸化传递可将环境信息输入和将节律信息输出生物钟核心.

Cyanobacteria are simple organisms which possess an endogenous circadian clock. Although the cyanobacterial clock has the same fundamental properties as circadian clocks in eukaryotes, its components are non-homologous to those of eukaryotes. The clock core of the cyanobacteria consists of the kai gene cluster and three Kai proteins KaiA, KaiB and KaiC, which the kai genes encode. The interactions among the Kai proteins modulate the phosphorylation state of KaiC, which generates circadian rhythm. The KaiC phosphorylation cycle constitutes the pacemaker of the cyanobacterial circadian rhythm. And signal transduction into and out of the clock core could occur via histidine protein kinase-based phosphorylation relays.