6y3d

Publication Abstract from PubMed

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 [(alphabeta)(3)](2) hexamer, with the phycocyanobilin chromophore attached to Cys84alpha, Cys82beta and Cys153beta. 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 (alphabeta)(3)/(alphabeta)(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.

X-ray structure of C-phycocyanin from Galdieria phlegrea: Determinants of thermostability and comparison with a C-phycocyanin in the entire phycobilisome.,Ferraro G, Imbimbo P, Marseglia A, Lucignano R, Monti DM, Merlino A Biochim Biophys Acta Bioenerg. 2020 Sep 1;1861(9):148236. doi: , 10.1016/j.bbabio.2020.148236. Epub 2020 May 30. PMID:32479753^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.