ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Photosynthesis and Photobiology
This article is part of the Research TopicUnraveling Energy Transfer Processes in Photosynthetic ComplexesView all articles
Structural analysis of PSI-ACPI and PSII-ACPII supercomplexes from a cryptophyte alga Rhodomonas sp. NIES-2332
Provisionally accepted
Wenyue ZhangNozomi YoneharaMizuki IshiiHaowei JiangRomain La Rocca
Pi-Cheng Tsai
Hongjie LiKoji Kato
Fusamichi Akita*
Jian-Ren Shen*- Okayama University, Okayama, Japan
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
Light energy is converted to chemical energy by two photosystems (PSI and PSII) in complex with their light-harvesting complex proteins (LHCI and LHCII) in photosynthesis. Rhodomonas is a member of cryptophyte alga whose LHCs contain unique chlorophyll a/c proteins (ACPs) and phycobiliproteins. We purified PSI-ACPI and PSII-ACPII supercomplexes from a cryptophyte Rhodomonas sp. NIES-2332 and analyzed their structures at high resolutions of 2.08 Å and 2.17 Å, respectively, using cryo-electron microscopy. These structures are largely similar to those reported previously from two other species of cryptophytes, but exhibited some differences in both the pigment locations and subunit structures. A part of the antenna subunits of both photosystems is shifted compared with the previously reported structures from other species of cryptophytes, suggesting some differences in the energy transfer rates from the antenna to the PSI and PSII cores. Newly identified lipids are found to occupy the interfaces between the antennae and cores, which may be important for assembly and stabilization of the supercomplexes. Water molecules surrounding three iron-sulfur clusters of the PSI core are found in our the high-resolution structure, some of which are conserved from cyanobacteria to higher plants but some are different. In addition, our structure of PSII-ACPII lacks the subunits of oxygen-evolving complex as well as the Mn4CaO5 cluster, suggesting that the cells are in the S-growth phase, yet the PSI-ACPI structure showed the binding of PsaQ, suggesting that it is in an L-phase. These results suggest that the S-phase and L-phase can co-exist in the cryptophytic cells. The high-resolution structures of both PSI-ACPIs and PSII-ACPIIs solved in this study provide a more solid structural basis for elucidating the energy transfer and quenching mechanisms in this group of the organisms.
Keywords: Cryptophytes, Rhodomonas, photosystem I, photosystem II, light-harvesting complex, Photosynthesis
Received: 01 Oct 2025; Accepted: 12 Nov 2025.
Copyright: © 2025 Zhang, Yonehara, Ishii, Jiang, La Rocca, Tsai, Li, Kato, Akita and Shen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Fusamichi Akita, fusamichi_a@cc.okayama-u.ac.jp
Jian-Ren Shen, shen@cc.okayama-u.ac.jp
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.