Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus

Abstract Gloeobacter diverged from other lineages early in cyanobacterial evolution, preferentially growing under low light intensity conditions. Among cyanobacteria, G. violaceus exhibits unique features, including lack of a thylakoid membrane and bundle-shaped antenna phycobilisomes (PBSs), densel...

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Main Authors: Jianfei Ma, Xin You, Shan Sun, Sen-Fang Sui
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-60673-w
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author Jianfei Ma
Xin You
Shan Sun
Sen-Fang Sui
author_facet Jianfei Ma
Xin You
Shan Sun
Sen-Fang Sui
author_sort Jianfei Ma
collection DOAJ
description Abstract Gloeobacter diverged from other lineages early in cyanobacterial evolution, preferentially growing under low light intensity conditions. Among cyanobacteria, G. violaceus exhibits unique features, including lack of a thylakoid membrane and bundle-shaped antenna phycobilisomes (PBSs), densely packed and well-organized on the plasma membrane. However, without high-resolution structures, it has remained unclear how G. violaceus PBSs assemble into a bundle-shaped configuration. Here we solve the cryo-EM structures of PBSs from G. violaceus cells cultured under low (Sr-PBS) or moderate (Lr-PBS) light intensity. These structures reveal two unique linker proteins, LRC 91kDa and LRC 81kDa, that play a key role in the PBS architecture. Analysis of the bilin arrangement indicates that the bundle-shaped structure allows efficient energy transfer among rods. Moreover, comparison between Lr-PBS and Sr-PBS uncovers a distinct mode of adaption to increased light intensity wherein the ApcA2-ApcB3-ApcD layer can be blocked from binding to the core by altering structural elements exclusively found in the G. violaceus LCM. This study illustrates previously unrecognized mechanisms of assembly and adaptation to varying light intensity in the bundle-shaped PBS of G. violaceus.
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institution Kabale University
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publishDate 2025-07-01
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spelling doaj-art-963655c9105b48a0b9b86d60d0ee9fb12025-08-20T03:37:38ZengNature PortfolioNature Communications2041-17232025-07-0116111310.1038/s41467-025-60673-wLight-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceusJianfei Ma0Xin You1Shan Sun2Sen-Fang Sui3State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structures, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structures, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structures, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structures, School of Life Sciences, Tsinghua UniversityAbstract Gloeobacter diverged from other lineages early in cyanobacterial evolution, preferentially growing under low light intensity conditions. Among cyanobacteria, G. violaceus exhibits unique features, including lack of a thylakoid membrane and bundle-shaped antenna phycobilisomes (PBSs), densely packed and well-organized on the plasma membrane. However, without high-resolution structures, it has remained unclear how G. violaceus PBSs assemble into a bundle-shaped configuration. Here we solve the cryo-EM structures of PBSs from G. violaceus cells cultured under low (Sr-PBS) or moderate (Lr-PBS) light intensity. These structures reveal two unique linker proteins, LRC 91kDa and LRC 81kDa, that play a key role in the PBS architecture. Analysis of the bilin arrangement indicates that the bundle-shaped structure allows efficient energy transfer among rods. Moreover, comparison between Lr-PBS and Sr-PBS uncovers a distinct mode of adaption to increased light intensity wherein the ApcA2-ApcB3-ApcD layer can be blocked from binding to the core by altering structural elements exclusively found in the G. violaceus LCM. This study illustrates previously unrecognized mechanisms of assembly and adaptation to varying light intensity in the bundle-shaped PBS of G. violaceus.https://doi.org/10.1038/s41467-025-60673-w
spellingShingle Jianfei Ma
Xin You
Shan Sun
Sen-Fang Sui
Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus
Nature Communications
title Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus
title_full Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus
title_fullStr Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus
title_full_unstemmed Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus
title_short Light-induced structural adaptation of the bundle-shaped phycobilisome from thylakoid-lacking cyanobacterium Gloeobacter violaceus
title_sort light induced structural adaptation of the bundle shaped phycobilisome from thylakoid lacking cyanobacterium gloeobacter violaceus
url https://doi.org/10.1038/s41467-025-60673-w
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AT shansun lightinducedstructuraladaptationofthebundleshapedphycobilisomefromthylakoidlackingcyanobacteriumgloeobacterviolaceus
AT senfangsui lightinducedstructuraladaptationofthebundleshapedphycobilisomefromthylakoidlackingcyanobacteriumgloeobacterviolaceus