3DBJ

Allophycocyanin from Thermosynechococcus vulcanus

3DBJ の概要

• エントリーDOI: 10.2210/pdb3dbj/pdb
• 分子名称: Allophycocyanin, PHYCOCYANOBILIN, ... (4 entities in total)
• 機能のキーワード: phycobilisome, light harvesting, photosynthesis, energy transfer, cyanobacteria
• 由来する生物種: Thermosynechococcus vulcanus; 詳細
• タンパク質・核酸の鎖数: 8
• 化学式量合計: 144488.76

構造登録者

Adir, N.,Klartag, M.,McGregor, A.,David, L. (登録日: 2008-06-01, 公開日: 2008-11-11, 最終更新日: 2023-11-01)

主引用文献

McGregor, A.,Klartag, M.,David, L.,Adir, N.
Allophycocyanin Trimer Stability and Functionality Are Primarily Due to Polar Enhanced Hydrophobicity of the Phycocyanobilin Binding Pocket
J.Mol.Biol., 384:406-421, 2008

PubMed Abstract: Allophycocyanin (APC) is the primary pigment-protein component of the cores of the phycobilisome antenna complex. In addition to an extremely high degree of amino acid sequence conservation, the overall structures of APC from both mesophilic and thermophilic species are almost identical at all levels of assembly, yet APC from thermophilic organisms should have structural attributes that prevent thermally induced denaturation. We determined the structure of APC from the thermophilic cyanobacterium Thermosynechococcus vulcanus to 2.9 A, reaffirming the conservation of structural similarity with APC from mesophiles. We provide spectroscopic evidence that T. vulcanus APC is indeed more stable at elevated temperatures in vitro, when compared with the APC from mesophilic species. APC thermal and chemical stability levels are further enhanced when monitored in the presence of high concentrations of buffered phosphate, which increases the strength of hydrophobic interactions, and may mimic the effect of cytosolic crowding. Absorption spectroscopy, size-exclusion HPLC, and native gel electrophoresis also show that the thermally or chemically induced changes in the APC absorption spectra that result in the loss of the prominent 652-nm band in trimeric APC are not a result of physical monomerization. We propose that the bathochromic shift that occurs in APC upon trimerization is due to the coupling of the hydrophobicity of the alpha84 phycocyanobilin cofactor environment created by a deep cleft formed by the beta subunit with highly charged flanking regions. This arrangement also provides the additional stability required by thermophiles at elevated temperatures. The chemical environment that induces the bathochromic shift in APC trimers is different from the source of shifts in the absorption of monomers of the terminal energy acceptors APC(B) and L(CM), as visualized by the building of molecular models.

PubMed: 18823993
DOI: 10.1016/j.jmb.2008.09.018

実験手法

X-RAY DIFFRACTION (2.9 Å)