8YPB

Cryo-EM structure of the LH1 complex from Allochromatium tepidum

8YPB の概要

• エントリーDOI: 10.2210/pdb8ypb/pdb
• EMDBエントリー: 39475
• 分子名称: Beta subunit of light-harvesting 1 complex, LH1 alpha polypeptide, BACTERIOCHLOROPHYLL A, ... (5 entities in total)
• 機能のキーワード: lh1 complex, photosynthesis
• 由来する生物種: Allochromatium tepidum; 詳細
• タンパク質・核酸の鎖数: 28
• 化学式量合計: 210445.80

構造登録者

Wang, G.-L.,Sun, S.,Yu, L.-J. (登録日: 2024-03-16, 公開日: 2025-02-19)

主引用文献

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

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: 39858518
DOI: 10.3390/biom15010124

実験手法

ELECTRON MICROSCOPY (2.45 Å)