A distinct double-ring LH1–LH2 photocomplex from an extremophilic phototroph
Halorhodospira (Hlr.) halophila strain BN9622 is an extremely halophilic and alkaliphilic phototrophic purple sulfur bacterium isolated from a hypersaline lake in the Libyan Desert whose total salinity exceeded 35% at pH 10.7. Here we present a cryo-EM structure of the native LH1-LH2 co-complex from strain BN9622 at 2.22 Å resolution. Surprisingly, the LH1-LH2 co-complex consists of a double-ring cylindrical structure with the larger LH1 ring encircling a smaller LH2 ring. The Hlr. halophila LH1 contains 18 αβ-subunits and additional bacteriochlorophyll a (BChl a) molecules that absorb maximally at 797 nm. The LH2 ring is composed of 9 αβ-subunits, and the BChl a molecules in the co-complex form extensive intra- and inter-complex networks to allow near 100% efficiency of energy transfer to its surrounding LH1. The additional LH1-B797 BChls a are located in such a manner that they facilitate exciton transfer from monomeric BChls in LH2 to the dimeric BChls in LH1. The structural features of the strain BN9622 LH1-LH2 co-complex may have evolved to allow a minimal LH2 complex to maximize excitation transfer to the core complex and effectively harvest light in the physiologically demanding ecological niche of this purple bacterium.
Authors
- R Morishita
- Masaharu Kondo (ORCID: https://orcid.org/0000-0003-2914-2662)
- Sakiko Nagashima (ORCID: https://orcid.org/0009-0000-4720-6346)
- Endang R. Purba (ORCID: https://orcid.org/0000-0001-6037-4504)
- Shinichi Takaichi (ORCID: https://orcid.org/0000-0002-1621-9141)
- Bruno M. Humbel (ORCID: https://orcid.org/0000-0002-7095-1368)
- Kazuna Nakata
- Yukihiro Kimura (ORCID: https://orcid.org/0000-0003-3747-0367)
- Akira Mizoguchi (ORCID: https://orcid.org/0000-0002-7492-2791)
- Kazutoshi Tani (ORCID: https://orcid.org/0000-0003-4835-154X)
- Kenji V. P. Nagashima (ORCID: https://orcid.org/0000-0002-4526-6625)
- Nobuo Hiwatashi
- Kazuhito Inoue
- Malgorzata Hall
- Takehisa Dewa (ORCID: https://orcid.org/0000-0002-9786-3114)
- Risa Kojima
- Yutaka Nagasawa (ORCID: https://orcid.org/0000-0002-9154-4585)
- Michael T. Madigan (ORCID: https://orcid.org/0000-0002-7785-4026)
- Long‐Jiang Yu (ORCID: https://orcid.org/0000-0002-4962-1049)
- Zheng‐Yu Wang‐Otomo
- Ryo Kanno
- M Kawakami
- Ikuo Satoh
- Yugo Isawa
Institutions
- Southern Illinois University Carbondale (US)
- Tokyo University of Agriculture (JP)
- Ritsumeikan University (JP)
- Okinawa Institute of Science and Technology Graduate University (JP)
- University of Tsukuba (JP)
- Mie University (JP)
- Nagoya Institute of Technology (JP)
- Chinese Academy of Sciences (CN)
- Juntendo University (JP)
- Kanagawa University (JP)
- Institute of Botany (CN)
- Ibaraki University (JP)
- Kobe University (JP)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-02-06
- DOI
- https://doi.org/10.1038/s41467-024-55811-9
- Citations
- 6
- Primary Topic
- Photosynthetic Processes and Mechanisms
- Type
- article
- Field-Weighted Citation Impact
- 4.84
Funders
- National Aeronautics and Space Administration
- Japan Agency for Medical Research and Development
- Japan Society for the Promotion of Science London
- Cabinet Office, Government of Japan
- Nuclear Safety and Security Commission
- Okinawa Institute of Science and Technology Graduate University
- University of Tsukuba
- Japan Society for the Promotion of Science