6KOL

Crystal structure of auracyanin from photosynthetic bacterium Roseiflexus castenholzii

6KOL の概要

• エントリーDOI: 10.2210/pdb6kol/pdb
• 分子名称: Blue (Type 1) copper domain protein, COPPER (II) ION, CHLORIDE ION, ... (4 entities in total)
• 機能のキーワード: auracyanin, roseiflexus castenholzii, electron transfer, blue copper protein, metal binding protein
• 由来する生物種: Roseiflexus castenholzii (strain DSM 13941 / HLO8)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 13336.20

構造登録者

Wang, C.,Zhang, C.Y.,Min, Z.Z.,Xin, Y.Y.,Xu, X.L. (登録日: 2019-08-12, 公開日: 2020-01-29, 最終更新日: 2023-11-22)

主引用文献

Wang, C.,Xin, Y.,Min, Z.,Qi, J.,Zhang, C.,Xu, X.
Structural basis underlying the electron transfer features of a blue copper protein auracyanin from the photosynthetic bacterium Roseiflexus castenholzii.
Photosyn. Res., 143:301-314, 2020

PubMed Abstract: Auracyanin (Ac) is a blue copper protein that mediates the electron transfer between Alternative Complex III (ACIII) and downstream electron acceptors in both fort chains of filamentous anoxygenic phototrophs. Here, we extracted and purified the air-oxidized RfxAc from the photoheterotrophically grown Roseiflexus castenholzii, and we illustrated the structural basis underlying its electron transferring features. Spectroscopic and enzymatic analyses demonstrated the reduction of air-oxidized RfxAc by the ACIII upon oxidation of menaquinol-4 and menaquinol-7. Crystal structures of the air-oxidized and Na-dithionite-reduced RfxAc at 2.2 and 2.0 Å resolutions, respectively, showed that the copper ions are coordinated by His77, His146, Cys141, and Met151 in minor different geometries. The Cu-S bond length increase of Met151, and the electron density Fourier differences at Cu and His77 demonstrated their essential roles in the dithionite-induced reduction. Structural comparisons further revealed that the RfxAc contains a Chloroflexus aurantiacus Ac-A-like copper binding pocket and a hydrophobic patch surrounding the exposed edge of His146 imidazole, as well as an Ac-B-like Ser- and Thr-rich polar patch located at a different site on the surface. These spectroscopic and structural features allow RfxAc to mediate electron transfers between the ACIII and redox partners different from those of Ac-A and Ac-B. These results provide a structural basis for further investigating the electron transfer and energy transformation mechanism of bacterial photosynthesis, and the diversity and evolution of electron transport chains.

PubMed: 31933173
DOI: 10.1007/s11120-020-00709-y

実験手法

X-RAY DIFFRACTION (2.211 Å)