Energizing the light harvesting antenna: Insight from CP29

Ioannidis, Nikolaos; Papadatos, Sotiris; Daskalakis, Vangelis

doi:10.1016/j.bbabio.2016.07.005

Cited by 13 publications

(39 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This type of mechanism would be in line with the presence of a “ cation sensitive site” on the stromal side of the thylakoids (Mills et al, 1976). Indeed, one from the subdomain of CP29 antenna from spinach has been proposed to be regulated by chemiosmotic factor (Ioannidis et al, 2016). However, the stimulatory effect of ions on NPQ of fluorescence is, apparently, against the proposed role of Mg 2+ in EDL theory (see Figure 4), where Mg 2+ induced high screening mode is observed by high Chl a fluorescence.…”

Section: Regulatory Role Of Protons and Ions In Triggering Non-photocmentioning

confidence: 99%

Role of Ions in the Regulation of Light-Harvesting

Kaňa

Govindjee

2016

Front. Plant Sci.

View full text Add to dashboard Cite

Regulation of photosynthetic light harvesting in the thylakoids is one of the major key factors affecting the efficiency of photosynthesis. Thylakoid membrane is negatively charged and influences both the structure and the function of the primarily photosynthetic reactions through its electrical double layer (EDL). Further, there is a heterogeneous organization of soluble ions (K+, Mg2+, Cl−) attached to the thylakoid membrane that, together with fixed charges (negatively charged amino acids, lipids), provides an electrical field. The EDL is affected by the valence of the ions and interferes with the regulation of “state transitions,” protein interactions, and excitation energy “spillover” from Photosystem II to Photosystem I. These effects are reflected in changes in the intensity of chlorophyll a fluorescence, which is also a measure of photoprotective non-photochemical quenching (NPQ) of the excited state of chlorophyll a. A triggering of NPQ proceeds via lumen acidification that is coupled to the export of positive counter-ions (Mg2+, K+) to the stroma or/and negative ions (e.g., Cl−) into the lumen. The effect of protons and anions in the lumen and of the cations (Mg2+, K+) in the stroma are, thus, functionally tightly interconnected. In this review, we discuss the consequences of the model of EDL, proposed by Barber (1980b) Biochim Biophys Acta 594:253–308) in light of light-harvesting regulation. Further, we explain differences between electrostatic screening and neutralization, and we emphasize the opposite effect of monovalent (K+) and divalent (Mg2+) ions on light-harvesting and on “screening” of the negative charges on the thylakoid membrane; this effect needs to be incorporated in all future models of photosynthetic regulation by ion channels and transporters.

show abstract

Section: Regulatory Role Of Protons and Ions In Triggering Non-photocmentioning

confidence: 99%

Role of Ions in the Regulation of Light-Harvesting

Kaňa

Govindjee

2016

Front. Plant Sci.

View full text Add to dashboard Cite

show abstract

“…For example, (i) the incoherent exciton transfer from the Chl to the short lived S 1 state of Cars has been implicated in the NPQ response 20 , i.e between Lutein 1 (Lut1) and the adjacent Chl-a, that interact more closely in an energy dissipating conformation 21 , (ii) Chl-Chl quenching states based on a charge-transfer character 22–24 have also been implicated in quenching, (iii) the neoxanthin (Neo) and the adjacent Chl-b, that interact more closely in an energy dissipating form 25, 26 , (iv) the Chl-614 pigment near the helix-D of the LHCs (Fig. 1a), where a conformational change in the helix has been proposed to alter the adjacent Chl macrocycle to a dissipating form 27, 28 . But what could be the cascade of events that leads from the well-established lumen acidification that triggers qE, to the obscure protein conformational changes and finally to the quenching site(s) and dynamics ?…”

Section: Introductionmentioning

confidence: 99%

“…Large scale all-atom Classical Molecular Dynamics (CMD), Metadynamics and full Quantum ( ab initio ) simulations are employed herein, as powerful tools 16, 28–32 , to give insight into the LHCs response under ΔpH − ΔΨ 5 and the Vio−Zea conversion 6 , in terms of induced conformational changes that can then be associated with affected quenching sites. We simulate the NPQ conditions by a perturbation in the thylakoid lumen, adding H + , and salt (KCl) gradients 28 .…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…We simulate the NPQ conditions by a perturbation in the thylakoid lumen, adding H + , and salt (KCl) gradients 28 . Four Lumen states are probed per LHC: low pH < 6 (higher energization) and high pH > 6 (lower energization), with a ±1 tolerance in combination with the Δ(KCl) gradient (lumen – stroma) at 0.0 and 0.5 M 28 . Τhree different membrane-embedded LHCs models are built in such way (major LHCII from spinach and pea and minor CP29 from spinach) of around 40,000 atoms each, including the LHCII complex, a membrane patch of between 120–128 united-atom UA-POPC lipids and 8500 TIP3P 33 water molecules at 6.5 × 6.5 nm 2 lateral dimensions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A pathway for protective quenching in antenna proteins of Photosystem II

Papadatos

Charalambous

Daskalakis

2017

Sci Rep

Self Cite

View full text Add to dashboard Cite

Photosynthesis is common in nature, converting sunlight energy into proton motive force and reducing power. The increased spectral range absorption of light exerted by pigments (i.e. chlorophylls, Chls) within Light Harvesting Complexes (LHCs) proves an important advantage under low light conditions. However, in the exposure to excess light, oxidative damages and ultimately cell death can occur. A down-regulatory mechanism, thus, has been evolved (non-photochemical quenching, NPQ). The mechanistic details of its major component (qE) are missing at the atomic scale. The research herein, initiates on solid evidence from the current NPQ state of the art, and reveals a detailed atomistic view by large scale Molecular Dynamics, Metadynamics and ab initio Simulations. The results demonstrate a complete picture of an elaborate common molecular design. All probed antenna proteins (major LHCII from spinach-pea, CP29 from spinach) show striking plasticity in helix-D, under NPQ conditions. This induces changes in Qy bands in excitation and absorption spectra of the near-by pigment pair (Chl613-614) that could emerge as a new quenching site. Zeaxanthin enhances this plasticity (and possibly the quenching) even at milder NPQ conditions.

show abstract

Molecular dynamics simulations in photosynthesis

Liguori¹,

Croce²,

Marrink

et al. 2020

Photosynth Res

View full text Add to dashboard Cite

Photosynthesis is regulated by a dynamic interplay between proteins, enzymes, pigments, lipids, and cofactors that takes place on a large spatio-temporal scale. Molecular dynamics (MD) simulations provide a powerful toolkit to investigate dynamical processes in (bio)molecular ensembles from the (sub)picosecond to the (sub)millisecond regime and from the Å to hundreds of nm length scale. Therefore, MD is well suited to address a variety of questions arising in the field of photosynthesis research. In this review, we provide an introduction to the basic concepts of MD simulations, at atomistic and coarse-grained level of resolution. Furthermore, we discuss applications of MD simulations to model photosynthetic systems of different sizes and complexity and their connection to experimental observables. Finally, we provide a brief glance on which methods provide opportunities to capture phenomena beyond the applicability of classical MD.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

show abstract

Energizing the light harvesting antenna: Insight from CP29

Cited by 13 publications

References 55 publications

Role of Ions in the Regulation of Light-Harvesting

Role of Ions in the Regulation of Light-Harvesting

A pathway for protective quenching in antenna proteins of Photosystem II

Molecular dynamics simulations in photosynthesis

Contact Info

Product

Resources

About