8JC9

Cryo-EM structure of the LH1 complex from thermochromatium tepidum

Summary for 8JC9

• Entry DOI: 10.2210/pdb8jc9/pdb
• EMDB information: 36154
• Descriptor: LH1 alpha polypeptide, LH1 beta polypeptide, BACTERIOCHLOROPHYLL A, ... (6 entities in total)
• Functional Keywords: lh1 complex, photosynthesis
• Biological source: Thermochromatium tepidum; More
• Total number of polymer chains: 28
• Total formula weight: 212789.36

Authors

Wang, G.-L.,Yan, Y.-H.,Yu, L.-J. (deposition date: 2023-05-10, release date: 2024-11-13)

Primary citation

Yan, Y.H.,Wang, G.L.,Yue, X.Y.,Ma, F.,Madigan, M.T.,Wang-Otomo, Z.Y.,Zou, M.J.,Yu, L.J.
Molecular structure and characterization of the Thermochromatium tepidum light-harvesting 1 photocomplex produced in a foreign host.
Biochim Biophys Acta Bioenerg, 1865:149050-149050, 2024

PubMed Abstract: Purple phototrophic bacteria possess light-harvesting 1 and reaction center (LH1-RC) core complexes that play a key role in converting solar energy to chemical energy. High-resolution structures of LH1-RC and RC complexes have been intensively studied and have yielded critical insight into the architecture and interactions of their proteins, pigments, and cofactors. Nevertheless, a detailed picture of the structure and assembly of LH1-only complexes is lacking due to the intimate association between LH1 and the RC. To study the intrinsic properties and structure of an LH1-only complex, a genetic system was constructed to express the Thermochromatium (Tch.) tepidum LH1 complex heterologously in a modified Rhodospirillum rubrum mutant strain. The heterologously expressed Tch. tepidum LH1 complex was isolated in a pure form free of the RC and exhibited the characteristic absorption properties of Tch. tepidum. Cryo-EM structures of the LH1-only complexes revealed a closed circular ring consisting of either 14 or 15 αβ-subunits, making it the smallest completely closed LH1 complex discovered thus far. Surprisingly, the Tch. tepidum LH1-only complex displayed even higher thermostability than that of the native LH1-RC complex. These results reveal previously unsuspected plasticity of the LH1 complex, provide new insights into the structure and assembly of the LH1-RC complex, and show how molecular genetics can be exploited to study membrane proteins from phototrophic organisms whose genetic manipulation is not yet possible.

PubMed: 38806091
DOI: 10.1016/j.bbabio.2024.149050

Experimental method

ELECTRON MICROSCOPY (3.32 Å)