title: Probing the pH sensitivity of R-phycoerythrin: investigations of active conformational and functional variation.
abstract: Crystal structures of phycobiliproteins have provided valuable information regarding the conformations and amino acid organizations of peptides and chromophores, and enable us to investigate their structural and functional relationships with respect to environmental variations. In this work, we explored the pH-induced conformational and functional dynamics of R-phycoerythrin (R-PE) by means of absorption, fluorescence and circular dichroism spectra, together with analysis of its crystal structure. R-PE presents stronger functional stability in the pH range of 3.5-10 compared to the structural stability. Beyond this range, pronounced functional and structural changes occur. Crystal structure analysis shows that the tertiary structure of R-PE is fixed by several key anchoring points of the protein. With this specific association, the fundamental structure of R-PE is stabilized to present physiological spectroscopic properties, while local variations in protein peptides are also allowed in response to environmental disturbances. The functional stability and relative structural sensitivity of R-PE allow environmental adaptation.
authors.affiliation: State Key Lab of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, PR China.
authors.forename: Lu-Ning
authors.initials: LN
authors.lastname: Liu
authors.forename: Hai-Nan
authors.initials: HN
authors.lastname: Su
authors.forename: Shi-Gan
authors.initials: SG
authors.lastname: Yan
authors.forename: Si-Mi
authors.initials: SM
authors.lastname: Shao
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Xie
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Chen
authors.forename: Xi-Ying
authors.initials: XY
authors.lastname: Zhang
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: Zhou
authors.forename: Yu-Zhong
authors.initials: YZ
authors.lastname: Zhang
mesh_terms: D000042:Absorption; D000595:Amino Acid Sequence; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010446:Peptide Fragments / Q000737:chemistry; D010799:Phycoerythrin / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship
chemical_list: D010446:Peptide Fragments; D010799:Phycoerythrin