Quenching of Chlorophyll <i>a</i> Fluorescence in the Aggregates of LHCII:  Steady State Fluorescence and Picosecond Relaxation Kinetics

Васильев, С. В.; Kd, Irrgang; Schrötter, T.; Bergmann, Axel; Hj, Eichler; Ренгер, Г.

doi:10.1021/bi9625253

Cited by 94 publications

(116 citation statements)

References 36 publications

Supporting

Mentioning

100

Contrasting

Unclassified

Order By: Relevance

“…Interestingly, the change in pH does not influence the spectra of the components, which remain the same in UQ and Q conditions. This indicates that no (additional) aggregation is induced in the Q state, as new emission forms would have been expected if LHCII aggregates were forming (36,37). The data thus suggest that the low pH mainly "activates" LHCSR1.…”

Section: Discussionmentioning

confidence: 75%

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

Dinc¹,

Tian²,

Roy³

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

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.photosynthesis | light-harvesting | nonphotochemical quenching | green algae | thylakoid membranes P hotosynthetic organisms get their energy from light and have developed a series of mechanisms to respond to the changes in light intensity that occur in their natural environment (1, 2). This is particularly important in high-light conditions, as the energy absorbed in excess can induce photodamage, eventually leading to the death of the organism. Photosynthetic organisms are equipped with many pigment-protein complexes, most of which in plants and green algae are members of the light-harvesting complex (Lhc) multigenic family (3). These complexes maximize light absorption in low light, but can easily become overexcited in high light (4), when a large part of the absorbed light cannot be used for charge separation in the reaction centers of the photosystems. Especially when the changes in light intensity are very fast, and thus protein degradation is not an option, photoprotective mechanisms need to be switched on to avoid the formation of singlet oxygen. The most rapid response to high light intensity is the dissipation of a large part of the absorbed energy as heat in a series of processes known as nonphotochemical quenching (NPQ) (1,5,6).The general idea is that the LHCs can switch between a lightharvesting conformation, characterized by a long excited-state lifetime, and a quenched (Q) conformation that shows a shorter lifetime because of the presence of competing de-excitation processes (7). How this switch is induced and the nature of these de-excitation processes is a matter of debate. It is known that NPQ is triggered by low luminal pH, which is a signal for the overexcitation of the membrane; this activates the quenching processes (5, 8), which involves the proteins PsbS (in plants and mosses) (9, 10) and/or lightharvesting complex stress related (LHCSR) (in green algae, mosses, and diatoms) (10-12)....

show abstract

Section: Discussionmentioning

confidence: 75%

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

Dinc¹,

Tian²,

Roy³

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…To further confirm the absence of significant aggregation in our samples, the fluorescence spectra were measured at both 5 K and 80 K and compared with those from 19,58 . The 5 K 20 fluorescence spectrum of the trimeric LHCII sample is depicted in Figure 1C (blue curve) along with the absorption and action spectra.…”

Section: Lhciimentioning

confidence: 99%

Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

et al. 2011

View full text Add to dashboard Cite

Abstract. The parameters of barrier distributions on the protein energy landscape in the excited electronic state of the pigment / protein system have been determined by means of spectral hole burning for the lowest-energy pigments of CP43 core antenna complex and CP29 minor antenna complex of spinach Photosystem II, as well as of trimeric and monomeric LHCII complexes transiently associated with pea Photosystem I pool. It has been demonstrated that all of these complexes exhibit sixty to several hundred times lower SHB yields as compared to molecular glassy solids previously probed by means of the hole growth kinetics (HGK) measurements. Thus, the entities (groups of atoms) which participate in conformational changes in protein appear to be significantly larger and heavier than those in molecular glasses. No evidence for small (<1 cm -1 ) spectral shift tier of the spectral diffusion dynamics has been observed. Thus, our data most likely reflects the true barrier distributions of the intact protein and not

show abstract

“…[5][6][7][8][9] In addition to the light-harvesting function, LHCII is involved in the non-radiative dissipation of excess excitation energy, a process collectively referred to as non-photochemical quenching (NPQ) of Chl fluorescence, [10][11][12] a key mechanism for protection against photodamage under excess radiation levels. In vitro, significant quenching manifested in shortening a) Electronic mail: lambrev@brc.hu b) Electronic mail: howesiang@ntu.edu.sg of the Chl a excitation lifetime [13][14][15][16] and development of a farred emitting state 17,18 are observed upon protein aggregation of LHCII. Aggregation of LHCII in solution by means of removal of detergent provides a good in vitro model of LHCII in the quenched state.…”

Section: Introductionmentioning

confidence: 99%

Energy transfer dynamics in trimers and aggregates of light-harvesting complex II probed by 2D electronic spectroscopy

Enriquez

Akhtar

Zhang

et al. 2015

The Journal of Chemical Physics

View full text Add to dashboard Cite

The pathways and dynamics of excitation energy transfer between the chlorophyll (Chl) domains in solubilized trimeric and aggregated light-harvesting complex II (LHCII) are examined using two-dimensional electronic spectroscopy (2DES). The LHCII trimers and aggregates exhibit the unquenched and quenched excitonic states of Chl a, respectively. 2DES allows direct correlation of excitation and emission energies of coupled states over population time delays, hence enabling mapping of the energy flow between Chls. By the excitation of the entire Chl b Q y band, energy transfer from Chl b to Chl a states is monitored in the LHCII trimers and aggregates. Global analysis of the two-dimensional (2D) spectra reveals that energy transfer from Chl b to Chl a occurs on fast and slow time scales of 240-270 fs and 2.8 ps for both forms of LHCII. 2D decay-associated spectra resulting from the global analysis identify the correlation between Chl states involved in the energy transfer and decay at a given lifetime. The contribution of singlet-singlet annihilation on the kinetics of Chl energy transfer and decay is also modelled and discussed. The results show a marked change in the energy transfer kinetics in the time range of a few picoseconds. Owing to slow energy equilibration processes, long-lived intermediate Chl a states are present in solubilized trimers, while in aggregates, the population decay of these excited states is significantly accelerated, suggesting that, overall, the energy transfer within the LHCII complexes is faster in the aggregated state. C 2015 AIP Publishing LLC. [http://dx

show abstract

Quenching of Chlorophyll a Fluorescence in the Aggregates of LHCII: Steady State Fluorescence and Picosecond Relaxation Kinetics

Cited by 94 publications

References 36 publications

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

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

Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

Energy transfer dynamics in trimers and aggregates of light-harvesting complex II probed by 2D electronic spectroscopy

Contact Info

Product

Resources

About