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Title | High-resolution structure and biochemical properties of the LH1-RC photocomplex from the model purple sulfur bacterium, Allochromatium vinosum. |
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Journal, issue, pages | Commun Biol, Vol. 7, Issue 1, Page 176, Year 2024 |
Publish date | Feb 12, 2024 |
Authors | Kazutoshi Tani / Ryo Kanno / Ayaka Harada / Yuki Kobayashi / Akane Minamino / Shinji Takenaka / Natsuki Nakamura / Xuan-Cheng Ji / Endang R Purba / Malgorzata Hall / Long-Jiang Yu / Michael T Madigan / Akira Mizoguchi / Kenji Iwasaki / Bruno M Humbel / Yukihiro Kimura / Zheng-Yu Wang-Otomo / |
PubMed Abstract | The mesophilic purple sulfur phototrophic bacterium Allochromatium (Alc.) vinosum (bacterial family Chromatiaceae) has been a favored model for studies of bacterial photosynthesis and sulfur ...The mesophilic purple sulfur phototrophic bacterium Allochromatium (Alc.) vinosum (bacterial family Chromatiaceae) has been a favored model for studies of bacterial photosynthesis and sulfur metabolism, and its core light-harvesting (LH1) complex has been a focus of numerous studies of photosynthetic light reactions. However, despite intense efforts, no high-resolution structure and thorough biochemical analysis of the Alc. vinosum LH1 complex have been reported. Here we present cryo-EM structures of the Alc. vinosum LH1 complex associated with reaction center (RC) at 2.24 Å resolution. The overall structure of the Alc. vinosum LH1 resembles that of its moderately thermophilic relative Alc. tepidum in that it contains multiple pigment-binding α- and β-polypeptides. Unexpectedly, however, six Ca ions were identified in the Alc. vinosum LH1 bound to certain α1/β1- or α1/β3-polypeptides through a different Ca-binding motif from that seen in Alc. tepidum and other Chromatiaceae that contain Ca-bound LH1 complexes. Two water molecules were identified as additional Ca-coordinating ligands. Based on these results, we reexamined biochemical and spectroscopic properties of the Alc. vinosum LH1-RC. While modest but distinct effects of Ca were detected in the absorption spectrum of the Alc. vinosum LH1 complex, a marked decrease in thermostability of its LH1-RC complex was observed upon removal of Ca. The presence of Ca in the photocomplex of Alc. vinosum suggests that Ca-binding to LH1 complexes may be a common adaptation in species of Chromatiaceae for conferring spectral and thermal flexibility on this key component of their photosynthetic machinery. |
External links | Commun Biol / PubMed:38347078 / PubMed Central |
Methods | EM (single particle) |
Resolution | 2.24 Å |
Structure data | EMDB-37465, PDB-8wdu: EMDB-37466, PDB-8wdv: |
Chemicals | ChemComp-HEM: ChemComp-MG: ChemComp-Z41: ChemComp-PLM: ChemComp-PGV: ChemComp-BCL: ChemComp-BPH: ChemComp-UQ8: ChemComp-LMT: ChemComp-CDL: ChemComp-FE: ChemComp-MQ8: ChemComp-CRT: ChemComp-CA: ChemComp-LDA: ChemComp-HOH: |
Source |
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Keywords | PHOTOSYNTHESIS / LH1-RC COMPLEX / PURPLE SULFUR BACTERIA |