Protein-Protein Interactions in the Cyanobacterial Circadian Clock: Structure of KaiA Dimer in Complex with C-Terminal KaiC Peptides at 2.8 Å Resolution.
Protein-Protein Interactions in the Cyanobacterial Circadian Clock: Structure of KaiA Dimer in Complex with C-Terminal KaiC Peptides at 2.8 Å Resolution.
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DOI：
10.1021/acs.biochem.5b00694
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发表时间：
2015-07
期刊：
影响因子：
2.9
通讯作者：
R. Pattanayek;M. Egli
中科院分区：
文献类型：
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作者：
R. Pattanayek;M. Egli
在蓝藻生物钟中，KaiA、B和KaiC蛋白与ATP构成翻译后振荡器。KaiA刺激KaiC自身激酶，KaiB拮抗KaiA作用。KaiA接触KaiC六聚体的固有无序的C-末端区域以促进跨亚基界面的磷酸化。来自细长聚球藻的KaiA二聚体与两个KaiC C-末端20聚体肽结合的晶体结构表明，后者采用α-螺旋构象并主要通过疏水相互作用接触KaiA α-螺旋束。该复合物和具有截短C末端尾部的KaiC六聚体的晶体结构可以符合KaiA：KaiC复合物的电子显微镜（EM）密度。混合模型有助于合理化KaiA和KaiC突变体的时钟表型。
In the cyanobacterial circadian clock, the KaiA, -B, and -C proteins with ATP constitute a post-translational oscillator. KaiA stimulates the KaiC autokinase, and KaiB antagonizes KaiA action. KaiA contacts the intrinsically disordered C-terminal regions of KaiC hexamer to promote phosphorylation across subunit interfaces. The crystal structure of KaiA dimer from Synechococcus elongatus with two KaiC C-terminal 20mer peptides bound reveals that the latter adopt an α-helical conformation and contact KaiA α-helical bundles via mostly hydrophobic interactions. This complex and the crystal structure of KaiC hexamer with truncated C-terminal tails can be fit into the electron microscopy (EM) density of the KaiA:KaiC complex. The hybrid model helps rationalize clock phenotypes of KaiA and KaiC mutants.