8YPD
Cryo-EM structure of the LH1 complex from Allochromatium tepidum
Summary for 8YPD
| Entry DOI | 10.2210/pdb8ypd/pdb |
| Related | 8YPB |
| EMDB information | 39477 |
| Descriptor | Beta subunit of light-harvesting 1 complex, LH1 alpha subunit, BACTERIOCHLOROPHYLL A, ... (4 entities in total) |
| Functional Keywords | lh1 complex, photosynthesis |
| Biological source | Allochromatium tepidum More |
| Total number of polymer chains | 28 |
| Total formula weight | 179160.20 |
| Authors | |
| Primary citation | Zou, M.J.,Sun, S.,Wang, G.L.,Yan, Y.H.,Ji, W.,Wang-Otomo, Z.Y.,Madigan, M.T.,Yu, L.J. Probing the Dual Role of Ca 2+ in the Allochromatium tepidum LH1-RC Complex by Constructing and Analyzing Ca 2+ -Bound and Ca 2+ -Free LH1 Complexes. Biomolecules, 15:-, 2025 Cited by PubMed Abstract: The genome of the mildly thermophilic hot spring purple sulfur bacterium, (.) , contains a multigene family that encodes a series of α- and β-polypeptides, collectively forming a heterogeneous light-harvesting 1 (LH1) complex. The LH1, therefore, offers a unique model for studying an intermediate phenotype between phototrophic thermophilic and mesophilic bacteria, particularly regarding their LH1 transition and moderately enhanced thermal stability. Of the 16 α-polypeptides in the LH1, six α1 bind Ca to connect with β1- or β3-polypeptides in specific Ca-binding sites. Here, we use the purple bacterium strain H2 as a host to express Ca-bound and Ca-free LH1-only complexes composed of α- and β-polypeptides that either contain or lack the calcium-binding motif WxxDxI; purified preparations of each complex were then used to test how Ca affects their thermostability and spectral features. The cryo-EM structures of both complexes were closed circular rings consisting of 14 αβ-polypeptides. The absorption maximum of Ca-bound LH1 (α1/β1 and α1/β3) was at 894 nm, while that of Ca-free (α2/β1) was at 888 nm, indicating that Ca imparts a transition of 6 nm. Crucially for the ecological success of , Ca-bound LH1 complexes were more thermostable than Ca-free complexes, indicating that calcium plays at least two major roles in photosynthesis by -improving photocomplex stability and modifying its spectrum. PubMed: 39858518DOI: 10.3390/biom15010124 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.78 Å) |
Structure validation
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