title: Structural insights into the cold adaptation of the photosynthetic pigment-protein C-phycocyanin from an Arctic cyanobacterium.
abstract: The cold adaptation mechanism of phycobiliproteins, the major photosynthetic pigment-proteins in cyanobacteria and red algae, has rarely been studied. Here we reported the biochemical, structural, and molecular dynamics simulation study of the C-phycocyanin from Arctic cyanobacterial strain Pseudanabaena sp. LW0831. We characterized the phycobilisome components of LW0831 and obtained their gene sequences. Compared to the mesophilic counterpart from Arthrospira platensis (Ar-C-PC), LW0831 C-phycocyanin (Ps-C-PC) has a decreased thermostability (∆Tmof -16°C), one of the typical features of cold-adapted enzymes. To uncover its structural basis, we resolved the crystal structure of Ps-C-PC 1 at 2.04Å. Consistent with the decrease in thermostability, comparative structural analyses revealed decreased intra-trimer and inter-trimer interactions in Ps-C-PC 1, compared to Ar-C-PC. However, comparative molecular dynamics simulations indicated that Ps-C-PC 1 shows similar flexibilities to Ar-C-PC for both the (αβ)3trimer and (αβ)6hexamer. Therefore, the optimization mode is clearly different from cold-adapted enzymes, which usually have increased flexibilities. Detailed analyses demonstrated different optimization modes for the α and β subunits and it was revealed that hydrophobic interactions are key to this difference, though salt bridges, hydrogen bonds, and surface hydrophobicity are also involved. This study is the first report of the structure of cold-adapted phycobiliproteins and provides insights into the cold-adaptation strategies of non-enzyme proteins.
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Hai-Nan
authors.initials: HN
authors.lastname: Su
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Qian-Min
authors.initials: QM
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Chun-Yang
authors.initials: CY
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Li
authors.affiliation: SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.affiliation: SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Xi-Ying
authors.initials: XY
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Qi-Long
authors.initials: QL
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Yu-Zhong
authors.initials: YZ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Institute of Marine Science and Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China. Electronic address: xbb@sdu.edu.cn.
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Xie
mesh_terms: D003080:Cold Temperature; D003460:Crystallization; D000458:Cyanobacteria / Q000737:chemistry*; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D010788:Photosynthesis; D052979:Phycobiliproteins / Q000737:chemistry*; D010798:Phycocyanin / Q000737:chemistry*; D011486:Protein C / Q000737:chemistry*; D055550:Protein Stability
chemical_list: D052979:Phycobiliproteins; D011486:Protein C; D010798:Phycocyanin
keywords: Algae; Crystallization; Flexibility; Photosynthesis; Phycobiliprotein; Stability