Protein–Protein Interactions Induce pH-Dependent and Zeaxanthin-Independent Photoprotection in the Plant Light-Harvesting Complex, LHCII

AbstractUnderstanding photosynthetic light harvesting requires knowledge of the molecular mechanisms that dissipate excess energy in thylakoids. However, it remains unclear how the physical environment of light-harvesting complex II (LHCII) influences the process of chlorophyll de-excitation. Here, we demonstrate that protein-protein interactions between LHCIIs affect the optical properties of LHCII and thus influence the total energy budget. Aggregation of LHCII in the dark altered its absorption properties, independent of the amount of prior light exposure. We also revisited the triplet excited state involved in light-induced fluorescence quenching and found another relaxation pathway involving emission in the green region, which might be related to triplet excited energy transfer to neighboring carotenoids and annihilation processes that result in photoluminescence. LHCII- containing liposomes with different protein densities exhibited altered fluorescence and scattering properties. Our results suggest that macromolecular reorganization affects overall optical properties, which need to be addressed to compare the level of energy dissipation.

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Lipid-protein Interactions in Crystals of Plant Light-harvesting Complex

Journal of Molecular Biology ◽

10.1006/jmbi.1993.1591 ◽

1993 ◽

Vol 234 (2) ◽

pp. 347-356 ◽

Cited By ~ 229

Author(s):

Stephan Nußberger ◽

Karoline Dörr ◽

Da Neng Wang ◽

Werner Kühlbrandt

Keyword(s):

Protein Interactions ◽

Light Harvesting ◽

Light Harvesting Complex ◽

Lipid Protein Interactions

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β-Catenin is a pH sensor with decreased stability at higher intracellular pH

The Journal of Cell Biology ◽

10.1083/jcb.201712041 ◽

2018 ◽

Vol 217 (11) ◽

pp. 3965-3976 ◽

Cited By ~ 17

Author(s):

Katharine A. White ◽

Bree K. Grillo-Hill ◽

Mario Esquivel ◽

Jobelle Peralta ◽

Vivian N. Bui ◽

...

Keyword(s):

Intracellular Ph ◽

Protein Interactions ◽

Mammalian Cells ◽

Ph Sensor ◽

Adherens Junction ◽

Protein Protein Interactions ◽

Adherens Junction Protein ◽

Junction Protein ◽

Evolutionarily Conserved ◽

Ph Dependent

β-Catenin functions as an adherens junction protein for cell–cell adhesion and as a signaling protein. β-catenin function is dependent on its stability, which is regulated by protein–protein interactions that stabilize β-catenin or target it for proteasome-mediated degradation. In this study, we show that β-catenin stability is regulated by intracellular pH (pHi) dynamics, with decreased stability at higher pHi in both mammalian cells and Drosophila melanogaster. β-Catenin degradation requires phosphorylation of N-terminal residues for recognition by the E3 ligase β-TrCP. While β-catenin phosphorylation was pH independent, higher pHi induced increased β-TrCP binding and decreased β-catenin stability. An evolutionarily conserved histidine in β-catenin (found in the β-TrCP DSGIHS destruction motif) is required for pH-dependent binding to β-TrCP. Expressing a cancer-associated H36R–β-catenin mutant in the Drosophila eye was sufficient to induce Wnt signaling and produced pronounced tumors not seen with other oncogenic β-catenin alleles. We identify pHi dynamics as a previously unrecognized regulator of β-catenin stability, functioning in coincidence with phosphorylation.

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A transcriptional regulatory circuit for the photosynthetic acclimation of microalgae to carbon dioxide limitation

10.1101/2020.07.09.195545 ◽

2020 ◽

Author(s):

Olga Blifernez-Klassen ◽

Hanna Berger ◽

Birgit Gerlinde Katharina Mittmann ◽

Viktor Klassen ◽

Louise Schelletter ◽

...

Keyword(s):

Carbon Dioxide ◽

Protein Interactions ◽

Prolonged Exposure ◽

Light Harvesting ◽

Low Carbon ◽

Protein Protein Interactions ◽

Regulatory Circuit ◽

Expression Of Genes ◽

Transcriptional Regulatory ◽

Squamosa Promoter Binding Protein

ABSTRACTIn green microalgae, prolonged exposure to inorganic carbon depletion requires long-term acclimation responses, based on a modulated expression of genes and adjusting photosynthetic activity to the prevailing supply of carbon dioxide. Here, we depict a microalgal regulatory cycle, adjusting the light-harvesting capacity at PSII to the prevailing supply of carbon dioxide in Chlamydomonas reinhardtii. It engages a newly identified low carbon dioxide response factor (LCRF), which belongs to the Squamosa promoter binding protein (SBP) family of transcription factors, and the previously characterized cytosolic translation repressor NAB1. LCRF combines a DNA-binding SBP domain with a conserved domain for protein-protein interactions and transcription of the LCRF gene is rapidly induced by carbon dioxide depletion. LCRF activates transcription of the NAB1 gene by specifically binding to tetranucleotide motifs present in its promoter. Accumulation of the NAB1 protein enhances translational repression of its prime target mRNA, encoding the PSII-associated major light-harvesting protein LHCBM6. The resulting reduction of the PSII antenna size helps maintaining a low excitation during the prevailing carbon dioxide limitation. Analyses of low carbon dioxide acclimation in nuclear insertion mutants devoid of a functional LCRF gene confirm the essentiality of this novel transcription factor for the regulatory circuit.

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Chromophore−Chromophore and Chromophore−Protein Interactions in Monomeric Light-Harvesting Complex II of Green Plants Studied by Spectral Hole Burning and Fluorescence Line Narrowing

The Journal of Physical Chemistry B ◽

10.1021/jp900836p ◽

2009 ◽

Vol 113 (31) ◽

pp. 10870-10880 ◽

Cited By ~ 33

Author(s):

Jörg Pieper ◽

Margus Rätsep ◽

Klaus-Dieter Irrgang ◽

Arvi Freiberg

Keyword(s):

Protein Interactions ◽

Light Harvesting ◽

Hole Burning ◽

Spectral Hole Burning ◽

Light Harvesting Complex ◽

Spectral Hole ◽

Line Narrowing ◽

Light Harvesting Complex Ii ◽

Fluorescence Line ◽

Fluorescence Line Narrowing

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LHCSR1 induces a fast and reversible pH-dependent fluorescence quenching in LHCII in Chlamydomonas reinhardtii cells

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1605380113 ◽

2016 ◽

Vol 113 (27) ◽

pp. 7673-7678 ◽

Cited By ~ 44

Author(s):

Emine Dinc ◽

Lijin Tian ◽

Laura M. Roy ◽

Robyn Roth ◽

Ursula Goodenough ◽

...

Keyword(s):

Chlamydomonas Reinhardtii ◽

Light Harvesting ◽

Ph Sensor ◽

Complex Stress ◽

Minimal Cell ◽

Light Harvesting Complex ◽

In Vivo Experiments ◽

Ph Dependent

To avoid photodamage, photosynthetic organisms are able to thermally dissipate the energy absorbed in excess in a process known as nonphotochemical quenching (NPQ). Although NPQ has been studied extensively, the major players and the mechanism of quenching remain debated. This is a result of the difficulty in extracting molecular information from in vivo experiments and the absence of a validation system for in vitro experiments. Here, we have created a minimal cell of the green alga Chlamydomonas reinhardtii that is able to undergo NPQ. We show that LHCII, the main light harvesting complex of algae, cannot switch to a quenched conformation in response to pH changes by itself. Instead, a small amount of the protein LHCSR1 (light-harvesting complex stress related 1) is able to induce a large, fast, and reversible pH-dependent quenching in an LHCII-containing membrane. These results strongly suggest that LHCSR1 acts as pH sensor and that it modulates the excited state lifetimes of a large array of LHCII, also explaining the NPQ observed in the LHCSR3-less mutant. The possible quenching mechanisms are discussed.

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