8Z82

Photosynthetic LH1-RC-HiPIP complex from the purple bacterium Halorhodospira halophila

Summary for 8Z82

• Entry DOI: 10.2210/pdb8z82/pdb
• EMDB information: 39836
• Descriptor: Photosynthetic reaction center cytochrome c subunit, HEME C, MAGNESIUM ION, ... (24 entities in total)
• Functional Keywords: lh1-rc, photosynthesis
• Biological source: Halorhodospira halophila; More
• Total number of polymer chains: 37
• Total formula weight: 507041.31

Authors

Tani, K.,Kanno, R.,Nagashima, K.V.P.,Hiwatashi, N.,Kawakami, M.,Nakata, K.,Nagashima, S.,Inoue, K.,Takaichi, S.,Purba, E.R.,Hall, M.,Yu, L.-J.,Madigan, M.T.,Mizoguchi, A.,Humbel, B.M.,Kimura, Y.,Wang-Otomo, Z.-Y. (deposition date: 2024-04-21, release date: 2025-01-29)

Primary citation

Tani, K.,Kanno, R.,Nagashima, K.V.P.,Kawakami, M.,Hiwatashi, N.,Nakata, K.,Nagashima, S.,Inoue, K.,Takaichi, S.,Purba, E.R.,Hall, M.,Yu, L.J.,Madigan, M.T.,Mizoguchi, A.,Humbel, B.M.,Kimura, Y.,Wang-Otomo, Z.Y.
A Native LH1-RC-HiPIP Supercomplex from an Extremophilic Phototroph.
Commun Biol, 8:42-42, 2025

PubMed Abstract: Halorhodospira (Hlr.) halophila strain BN9622 is an extremely halophilic and alkaliphilic purple phototrophic bacterium and has been widely used as a model for exploring the osmoadaptive and photosynthetic strategies employed by phototrophic extreme halophiles that enable them to thrive in hypersaline environments. Here we present the cryo-EM structures of (1) a unique native Hlr. halophila triple-complex formed from light-harvesting (LH1), the reaction center (RC), and high-potential iron-sulfur protein (HiPIP) at 2.44 Å resolution, and (2) a HiPIP-free LH1-RC complex at 2.64 Å resolution. Differing from the LH1 in the Hlr. halophila LH1-LH2 co-complex where LH1 encircles LH2, the RC-associated LH1 complex consists of 16 (rather than 18) αβ-subunits circularly surrounding the RC. These distinct forms of LH1 indicate that the number of subunits in a Hlr. halophila LH1 complex is flexible and its size is a function of the photocomplex it encircles. Like LH1 in the LH1-LH2 co-complex, the RC-associated LH1 complex also contained two forms of αβ-polypeptides and both dimeric and monomeric molecules of bacteriochlorophyll a. The majority of the isolated Hlr. halophila LH1-RC complexes contained the electron donor HiPIP bound to the surface of the RC cytochrome subunit near the heme-1 group. The bound HiPIP consisted of an N-terminal functional domain and a long C-terminal extension firmly attached to the cytochrome subunit. Despite overall highly negative surface-charge distributions for both the cytochrome subunit and HiPIP, the interface between the two proteins was relatively uncharged and neutral, forming a pathway for electron tunneling. The structure of the Hlr. halophila LH1-RC-HiPIP complex provides insights into the mechanism of light energy acquisition coupled with a long-distance electron donating process toward the charge separation site in a multi-extremophilic phototroph.

PubMed: 39799244
DOI: 10.1038/s42003-024-07421-w

Experimental method

ELECTRON MICROSCOPY (2.4 Å)