Light-Harvesting Protein LHCB4 Is Important for Stable Dimeric Organization of Photosystem II.
5 affiliations
- 1Department of Biophysics, Faculty of Science, Palacký University, Olomouc, Czech Republic.
- 2Department of Physics, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
- 3Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic.
- 4Institute of Experimental Botany of the Czech Academy of Sciences, Centre of Plant Structural and Functional Genomics, Olomouc, Czech Republic.
- 5Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
Abstract
Light-harvesting protein LHCB4 is a monomeric antenna of photosystem II (PSII) that connects the PSII core (C) with strongly (S) and moderately (M) bound LHCII trimers, forming the stable dimeric supercomplex C₂S₂M₂. LHCB4 is known to stabilize LHCII attachment to the PSII core dimer (C₂). Here, we show that LHCB4 is essential for the intrinsic stability of the PSII core dimer itself, a fundamental structural unit required for efficient photochemistry. In the lhcb4 mutant, clear-native PAGE revealed the absence of C₂S₂M₍₂₎ and only small amounts of C₂S₂ and C₂S supercomplexes. Single-particle electron microscopy identified two types of C₂S₍₂₎ supercomplexes: a canonical configuration with an empty LHCB4 site and a more abundant "packed" structure, arising from a relative shift of the C(S) monomers. However, most PSII particles were present as monomeric CS complexes with attached LHCB5 antenna. In contrast, PSII analyzed directly in thylakoid membranes retained the canonical C₂ organization and even formed nonparallel associations of C₂S₂ supercomplexes, indicating that the "packed" C₂S₂ and CS forms arise during isolation due to reduced PSII dimer stability. The PSII core dimer also readily disintegrates in the mutant lacking all monomeric antenna proteins (NoM), implying that LHCB4 is critical for the stability of the C₂ dimer itself. Consistently, lhcb4 plants exhibited reduced thermal stability of PSII macro-organization and photochemistry in vivo. Our findings demonstrate that LHCB4 is not merely a peripheral antenna connector, but also an important structural determinant of PSII core dimer stability, underscoring its essential role in efficient photochemistry and photoprotection.
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BibTeX
@article{vanska2026lightharvesting,
title = {{Light-Harvesting Protein LHCB4 Is Important for Stable Dimeric Organization of Photosystem II.}},
author = {Tereza Vánská and Monika Opatíková and Roman Kouřil and Zuzana Kučerová and Václav Karlický and Iva Ilíková and Marek Rác and Pavel Roudnický and Vojtěch Chýlek and Petr Ilík},
journal = {Physiologia plantarum},
year = {2026},
month = sep,
doi = {10.1111/ppl.71144},
url = {https://europepmc.org/article/MED/42853213},
note = {CC BY},
}
RIS
TY - JOUR
TI - Light-Harvesting Protein LHCB4 Is Important for Stable Dimeric Organization of Photosystem II.
AU - Tereza Vánská
AU - Monika Opatíková
AU - Roman Kouřil
AU - Zuzana Kučerová
AU - Václav Karlický
AU - Iva Ilíková
AU - Marek Rác
AU - Pavel Roudnický
AU - Vojtěch Chýlek
AU - Petr Ilík
PY - 2026
DA - 2026/09/01
JO - Physiologia plantarum
DO - 10.1111/ppl.71144
UR - https://europepmc.org/article/MED/42853213
AB - Light-harvesting protein LHCB4 is a monomeric antenna of photosystem II (PSII) that connects the PSII core (C) with strongly (S) and moderately (M) bound LHCII trimers, forming the stable dimeric supercomplex C₂S₂M₂. LHCB4 is known to stabilize LHCII attachment to the PSII core dimer (C₂). Here, we show that LHCB4 is essential for the intrinsic stability of the PSII core dimer itself, a fundamental structural unit required for efficient photochemistry. In the lhcb4 mutant, clear-native PAGE revealed the absence of C₂S₂M₍₂₎ and only small amounts of C₂S₂ and C₂S supercomplexes. Single-particle electron microscopy identified two types of C₂S₍₂₎ supercomplexes: a canonical configuration with an empty LHCB4 site and a more abundant "packed" structure, arising from a relative shift of the C(S) monomers. However, most PSII particles were present as monomeric CS complexes with attached LHCB5 antenna. In contrast, PSII analyzed directly in thylakoid membranes retained the canonical C₂ organization and even formed nonparallel associations of C₂S₂ supercomplexes, indicating that the "packed" C₂S₂ and CS forms arise during isolation due to reduced PSII dimer stability. The PSII core dimer also readily disintegrates in the mutant lacking all monomeric antenna proteins (NoM), implying that LHCB4 is critical for the stability of the C₂ dimer itself. Consistently, lhcb4 plants exhibited reduced thermal stability of PSII macro-organization and photochemistry in vivo. Our findings demonstrate that LHCB4 is not merely a peripheral antenna connector, but also an important structural determinant of PSII core dimer stability, underscoring its essential role in efficient photochemistry and photoprotection.
SN - 1399-3054
ER -