4RMP

Crystal structure of allophycocyanin from marine cyanobacterium Phormidium sp. A09DM

Summary for 4RMP

• Entry DOI: 10.2210/pdb4rmp/pdb
• Descriptor: Allophycocyanin, PHYCOCYANOBILIN, ... (4 entities in total)
• Functional Keywords: phycocyanobilin chromophore, globin-like fold (scop, 46457), light harvesting phycobiliprotein, photosynthesis
• Biological source: Phormidium rubidum A09DM; More
• Total number of polymer chains: 2
• Total formula weight: 36109.08

Authors

Kumar, V.,Gupta, G.D.,Sonani, R.R.,Madamwar, D. (deposition date: 2014-10-22, release date: 2015-05-13, Last modification date: 2023-09-20)

Primary citation

Sonani, R.R.,Gupta, G.D.,Madamwar, D.,Kumar, V.
Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM.
Plos One, 10:e0124580-e0124580, 2015

PubMed Abstract: Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of α- and β- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of α- and β- subunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of α- and β- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein.

PubMed: 25923120
DOI: 10.1371/journal.pone.0124580

Experimental method

X-RAY DIFFRACTION (2.506 Å)