1ON7

Unmethylated form of C-phycocyanin from Themosynechococcus vulcanus at 2.7A

1ON7 の概要

• エントリーDOI: 10.2210/pdb1on7/pdb
• 関連するPDBエントリー: 1I7Y 1KTP
• 分子名称: C-phycocyanin alpha subunit, C-phycocyanin beta subunit, PHYCOCYANOBILIN, ... (4 entities in total)
• 機能のキーワード: photosynthesis, antenna, phycobilisome, cyanobacteria
• 由来する生物種: Thermosynechococcus vulcanus; 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 37439.36

構造登録者

Adir, N.,Lerner, N. (登録日: 2003-02-27, 公開日: 2003-07-29, 最終更新日: 2023-10-25)

主引用文献

Adir, N.,Lerner, N.
The crystal structure of a novel unmethylated form of C-phycocyanin, a possible connector between cores and rods in pycobilisomes
J.Biol.Chem., 278:25926-25932, 2003

PubMed Abstract: A novel fraction of c-phycocyanin from the thermophilic cyanobacterium Thermosynechcoccus vulcanus, with an absorption maxima blue-shifted to 612 nm (PC612), has been purified from allophycocyanin and crystallized. The crystals belong to the P63 space group with cell dimensions of 153 A x 153 A x 59 A with a single (alphabeta) monomer in the asymmetric unit, resulting in a solvent content of 65%, and diffract to 2.7 A. The PC612 crystal structure has been determined by molecular replacement and refined to a crystallographic R-factor of 20.9% (Rfree = 27.8%). The crystal packing in this form shows that the PC612 form of phycocyanin does not associate into hexamers and that its association with adjacent trimers in the unit cell is very different from that found in a previously determined structure of the normal form of T. vulcanus phycocyanin, which absorbs at 620 nm. Analysis of the PC612 structure shows that the alpha subunits, which typically form the interface between two trimers within a hexamer, have a high degree of flexibility, as indicated by elevated B-factors in portions of helices B, E, and G. Examination of calculated electron density omit maps shows that unlike all other structures of phycobiliproteins determined so far, the Asnbeta72 residue is not methylated, explaining the blue-shift in its absorption spectra. On the basis of the results presented here, we suggest that this new form of trimeric phycocyanin may constitute a special minor component of the phycobilisome and may form the contact between the phycocyanin rods and the allophycocyanin core.

PubMed: 12709431
DOI: 10.1074/jbc.M302838200

実験手法

X-RAY DIFFRACTION (2.7 Å)