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X-ray structure of C-phycocyanin from Galdieria phlegrea: Determinants of thermostability and comparison with a C-phycocyanin in the entire phycobilisome.
Biochimica et Biophysica Acta (BBA) - Bioenergetics ( IF 4.3 ) Pub Date : 2020-05-30 , DOI: 10.1016/j.bbabio.2020.148236
Giarita Ferraro 1 , Paola Imbimbo 1 , Angela Marseglia 1 , Rosanna Lucignano 1 , Daria Maria Monti 1 , Antonello Merlino 2
Affiliation  

Galdieria phlegrea is a polyextremophilic red alga belonging to Cyanidiophyceae. Galdieria phlegrea C-phycocyanin (GpPC), an abundant light-harvesting pigment with an important role in energy capture and transfer to photosystems, is the C-phycocyanin (C-PC) with the highest thermal stability described so far. GpPC also presents interesting antioxidant and anticancer activities. The X-ray structure of the protein was here solved. GpPC is a [(αβ)3]2 hexamer, with the phycocyanobilin chromophore attached to Cys84α, Cys82β and Cys153β. Details of geometry and interaction with solvent of the chromophores are reported. Comparison with the structure of a C-PC in the entire Porphyridium purpureum phycobilisome system reveals that linker polypeptides have a significant effect on the local structure of the chromophores environment. Comparative analyses with the structures of other purified C-PCs, which were carried out including re-refined models of G. sulphuraria C-PC, reveal that GpPC presents a significantly higher number of inter-trimer salt bridges. Notably, the higher number of salt bridges at the (αβ)3/(αβ)3 interface is not due to an increased number of charged residues in this region, but to subtle conformational variations of their side chains, which are the result of mutations of close polar and non-polar residues.



中文翻译:

白化病菌中C-藻蓝蛋白的X射线结构:热稳定性的决定因素以及与整个藻胆体中C-藻蓝蛋白的比较。

白化病菌Galdieria phlegrea)是属于蓝藻科的一种多极端性红藻。白化病菌C-藻蓝蛋白(GpPC)是一种迄今描述的热稳定性最高的C-藻蓝蛋白(C-PC),在能量捕获和转移至光系统中起着重要作用。GpPC还表现出有趣的抗氧化和抗癌活性。蛋白质的X射线结构在此已解决。GpPC是一种[(αβ)3 ] 2六聚体,藻蓝蛋白发色团附着在Cys84α,Cys82β和Cys153β上。报告了发色团的​​几何形状和与溶剂的相互作用的详细信息。与整个紫菜中C-PC的结构比较藻胆体系统揭示了接头多肽对生色团环境的局部结构具有重要影响。与其他纯化的C-PCs的结构进行了比较分析,包括对G. sulfuraria C-PC的重新精炼模型进行了分析,结果表明GpPC呈现出大量的三聚体间盐桥。值得注意的是,(αβ)3 /(αβ)3界面上盐桥的数量更多不是由于该区域带电残基的数量增加,而是由于其侧链的细微构象变化,这是突变的结果极性和非极性残基的残基。

更新日期:2020-05-30
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