scholarly journals Plant LHC-like proteins show robust folding and static non-photochemical quenching

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Petra Skotnicová ◽  
Hristina Staleva-Musto ◽  
Valentyna Kuznetsova ◽  
David Bína ◽  
Minna M. Konert ◽  
...  
Keyword(s):  
Site Directed Mutagenesis ◽  
Photochemical Quenching ◽  
Terminal Sequence ◽  
Light Harvesting Complexes ◽  
Direct Energy ◽  
Carotenoid Mutants ◽  
Life On Earth ◽  
Non Photochemical Quenching ◽  
Energy Plants ◽  
Chl Fluorescence

AbstractLife on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Plants collect photons by light harvesting complexes (LHC)—abundant membrane proteins containing chlorophyll and xanthophyll molecules. LHC-like proteins are similar in their amino acid sequence to true LHC antennae, however, they rather serve a photoprotective function. Whether the LHC-like proteins bind pigments has remained unclear. Here, we characterize plant LHC-like proteins (LIL3 and ELIP2) produced in the cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis). Both proteins were associated with chlorophyll a (Chl) and zeaxanthin and LIL3 was shown to be capable of quenching Chl fluorescence via direct energy transfer from the Chl Qy state to zeaxanthin S1 state. Interestingly, the ability of the ELIP2 protein to quench can be acquired by modifying its N-terminal sequence. By employing Synechocystis carotenoid mutants and site-directed mutagenesis we demonstrate that, although LIL3 does not need pigments for folding, pigments stabilize the LIL3 dimer.

scholarly journals Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Julianne M. Troiano ◽  
Federico Perozeni ◽  
Raymundo Moya ◽  
Luca Zuliani ◽  
Kwangryul Baek ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Complex Stress ◽  
Excess Energy ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Non Photochemical Quenching

AbstractUnder high light conditions, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating excess absorbed energy, which is called non-photochemical quenching (NPQ). In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via pH and serves as a quenching site. However, the mechanisms by which LHCSR3 functions have not been determined. Using a combined in vivo and in vitro approach, we identify two parallel yet distinct quenching processes, individually controlled by pH and carotenoid composition, and their likely molecular origin within LHCSR3 from Chlamydomonas reinhardtii. The pH-controlled quenching is removed within a mutant LHCSR3 that lacks the protonable residues responsible for sensing pH. Constitutive quenching in zeaxanthin-enriched systems demonstrates zeaxanthin-controlled quenching, which may be shared with other light-harvesting complexes. We show that both quenching processes prevent the formation of damaging reactive oxygen species, and thus provide distinct timescales and mechanisms of protection in a changing environment.

scholarly journals Effects of Light Intensity on Cyclic Electron Flow Around PSI and its Relationship to Non-photochemical Quenching of Chl Fluorescence in Tobacco Leaves

2005 ◽  
Vol 46 (11) ◽  
pp. 1819-1830 ◽  
Author(s):  
Chikahiro Miyake ◽  
Sayaka Horiguchi ◽  
Amane Makino ◽  
Yuki Shinzaki ◽  
Hiroshi Yamamoto ◽  
...  
Keyword(s):  
Light Intensity ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Photochemical Quenching ◽  
Tobacco Leaves ◽  
Non Photochemical Quenching ◽  
Chl Fluorescence

scholarly journals Preface: Why grana?

1999 ◽  
Vol 26 (7) ◽  
pp. I
Author(s):  
Barry Osmond
Keyword(s):  
Light Harvesting ◽  
Photochemical Quenching ◽  
Dense Array ◽  
Metabolic Capacity ◽  
Light Harvesting Complexes ◽  
Protein Subunits ◽  
3 Dimensional ◽  
Functional Flexibility ◽  
Non Photochemical Quenching ◽  
Light Input

The importance of the functional flexibility of the light-harvesting complexes of photo-system II (LHCII) in accommodating the fluctuation in the balance between light input and metabolic capacity in plants is emphasised. This flexibility is provided for by a relatively complex assembly of protein subunits, the interactions between them being controlled by protonation, xanthophyll de-epoxidation and phosphorylation. It is suggested that the 3-dimensional order imposed upon this assembly of proteins by the grana is a vital aspect of the modulation of LHCII function. Grana establish the LHCII conformation needed for efficient light harvesting and help prevent the dense array of proteins from collapsing into a highly dissipative state. The grana then allow a controlled development of non-photochemical quenching under the driving force of violaxanthin de-epoxidation and protonation. In plants grown under different irradiances the different grana content and xanthophyll cycle pool size together allow maximum quantum yield in limiting light and an appropriate level of non-photochemical quenching in excess light.

scholarly journals Combined chlorophyll fluorescence techniques to study environmental impact on the mountain moss Polytrichum commune

2021 ◽  
Vol 11 (1) ◽  
pp. 161-173
Author(s):  
Gabriella Nora Maria Giudici
Keyword(s):  
Chlorophyll Fluorescence ◽  
Conformational Changes ◽  
Heat Dissipation ◽  
Fluorescence Induction ◽  
High Light ◽  
Chlorophyll Fluorescence Induction ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Polytrichum Commune ◽  
Non Photochemical Quenching

Two chlorophyll fluorescence (ChlF) methods were used to study the effects of high light (photoinhibition) and dehydration, common stressors of the alpine environment, on primary photosynthetic processes in the moss Polytrichum commune from the Czech Republic, the Jeseníky Mountains. Photoinhibition (PI) was studied in fully hydrated thalli of P. commune and during the period of spontaneous desiccation. Time courses of Kautsky kinetics (KK) of ChlF and derived parameters: maximum quantum yield (FV/FM), effective quantum yeld (ΦPSII), and non-photochemical quenching parameters, were measured before and after the samples were treated with high light (1500 µmol m-2 s-1 PAR) for 60 min. Dehydration effects were tested in two sets of experiments with a Pulse-Amplitude-Modulation fluorometry (PAM) and Fast Chlorophyll Fluorescence induction curve (OJIP) techniques. In PAM tests, the desiccating samples were exposed to saturating light pulses every 10 min. in order to obtain ΦPSII and non-photochemical quenching (NPQ). In the second dehydration experiment, OJIP transients of ChlF were repeatedly recorded, OJIP-derived ChlF parameters were plotted against relative water content (RWC) monitored during desiccation. Combined ChF techniques provided insights into the mechanisms activated during P. commune desiccation, such as dissipation of excess absorbed energy through heat dissipation, and conformational changes or destructions of the light harvesting complexes. Combination of stressors resulted in amplified interference with the photosynthetic machinery, even when the added stressor (dehydration) was applied in low dose.

Hypothesis: Are grana necessary for regulation of light harvesting?

1999 ◽  
Vol 26 (7) ◽  
pp. 659 ◽  
Author(s):  
Peter Horton
Keyword(s):  
Light Harvesting ◽  
Photochemical Quenching ◽  
Dense Array ◽  
Metabolic Capacity ◽  
Light Harvesting Complexes ◽  
Protein Subunits ◽  
3 Dimensional ◽  
Functional Flexibility ◽  
Non Photochemical Quenching ◽  
Light Input

The importance of the functional flexibility of the light-harvesting complexes of photo-system II (LHCII) in accommodating the fluctuation in the balance between light input and metabolic capacity in plants is emphasised. This flexibility is provided for by a relatively complex assembly of protein subunits, the interactions between them being controlled by protonation, xanthophyll de-epoxidation and phosphorylation. It is suggested that the 3-dimensional order imposed upon this assembly of proteins by the grana is a vital aspect of the modulation of LHCII function. Grana establish the LHCII conformation needed for efficient light harvesting and help prevent the dense array of proteins from collapsing into a highly dissipative state. The grana then allow a controlled development of non-photochemical quenching under the driving force of violaxanthin de-epoxidation and protonation. In plants grown under different irradiances the different grana content and xanthophyll cycle pool size together allow maximum quantum yield in limiting light and an appropriate level of non-photochemical quenching in excess light.

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