Equilibrium between quenched and nonquenched conformations of the major plant light-harvesting complex studied with high-pressure time-resolved fluorescence

B.F. van Oort, A. van Hoek, A.V. Ruban, H. van Amerongen

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Abstract

Nonphotochemical quenching (NPQ) of chlorophyll fluorescence plays an important role in the protection of plants against excessive light. Fluorescence quenching of the major light-harvesting complex (LHCII) provides a model system to study the mechanism of NPQ. The existence of both quenched and nonquenched states of LHCII has been postulated. We used time-resolved fluorescence and hydrostatic pressure to study differences between these states. Pressure shifts the thermodynamic equilibrium between the two states. The estimated volume difference was 5 mL/mol, indicating a local conformational switch. The estimated free energy difference was 7.0 kJ/mol: high enough to keep the quenched state population low under normal conditions, but low enough to switch in a controlled way. These properties are physiologically relevant properties, because they guarantee efficient light harvesting, while at the same time maintaining the capacity to switch to a quenched state. These results indicate that conformational changes of LHCII can play an important role in NPQ.
Original languageEnglish
Pages (from-to)7631-7637
Number of pages7
JournalThe Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical
Volume111
Issue number26
DOIs
Publication statusPublished - 2007

Fingerprint

Conformations
Quenching
Fluorescence
quenching
fluorescence
Switches
switches
chlorophylls
Chlorophyll
Hydrostatic pressure
thermodynamic equilibrium
hydrostatic pressure
Free energy
free energy
Thermodynamics
shift

Keywords

  • nonphotochemical energy-dissipation
  • chlorophyll-protein complex
  • photosystem-ii
  • green plants
  • chloroplast membranes
  • excitation dynamics
  • antenna complex
  • molecular-basis
  • lhcii
  • absorption

Cite this

@article{917ecec471994f479da9b6c0ab30125e,
title = "Equilibrium between quenched and nonquenched conformations of the major plant light-harvesting complex studied with high-pressure time-resolved fluorescence",
abstract = "Nonphotochemical quenching (NPQ) of chlorophyll fluorescence plays an important role in the protection of plants against excessive light. Fluorescence quenching of the major light-harvesting complex (LHCII) provides a model system to study the mechanism of NPQ. The existence of both quenched and nonquenched states of LHCII has been postulated. We used time-resolved fluorescence and hydrostatic pressure to study differences between these states. Pressure shifts the thermodynamic equilibrium between the two states. The estimated volume difference was 5 mL/mol, indicating a local conformational switch. The estimated free energy difference was 7.0 kJ/mol: high enough to keep the quenched state population low under normal conditions, but low enough to switch in a controlled way. These properties are physiologically relevant properties, because they guarantee efficient light harvesting, while at the same time maintaining the capacity to switch to a quenched state. These results indicate that conformational changes of LHCII can play an important role in NPQ.",
keywords = "nonphotochemical energy-dissipation, chlorophyll-protein complex, photosystem-ii, green plants, chloroplast membranes, excitation dynamics, antenna complex, molecular-basis, lhcii, absorption",
author = "{van Oort}, B.F. and {van Hoek}, A. and A.V. Ruban and {van Amerongen}, H.",
year = "2007",
doi = "10.1021/jp070573z",
language = "English",
volume = "111",
pages = "7631--7637",
journal = "The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical",
issn = "1520-6106",
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}

TY - JOUR

T1 - Equilibrium between quenched and nonquenched conformations of the major plant light-harvesting complex studied with high-pressure time-resolved fluorescence

AU - van Oort, B.F.

AU - van Hoek, A.

AU - Ruban, A.V.

AU - van Amerongen, H.

PY - 2007

Y1 - 2007

N2 - Nonphotochemical quenching (NPQ) of chlorophyll fluorescence plays an important role in the protection of plants against excessive light. Fluorescence quenching of the major light-harvesting complex (LHCII) provides a model system to study the mechanism of NPQ. The existence of both quenched and nonquenched states of LHCII has been postulated. We used time-resolved fluorescence and hydrostatic pressure to study differences between these states. Pressure shifts the thermodynamic equilibrium between the two states. The estimated volume difference was 5 mL/mol, indicating a local conformational switch. The estimated free energy difference was 7.0 kJ/mol: high enough to keep the quenched state population low under normal conditions, but low enough to switch in a controlled way. These properties are physiologically relevant properties, because they guarantee efficient light harvesting, while at the same time maintaining the capacity to switch to a quenched state. These results indicate that conformational changes of LHCII can play an important role in NPQ.

AB - Nonphotochemical quenching (NPQ) of chlorophyll fluorescence plays an important role in the protection of plants against excessive light. Fluorescence quenching of the major light-harvesting complex (LHCII) provides a model system to study the mechanism of NPQ. The existence of both quenched and nonquenched states of LHCII has been postulated. We used time-resolved fluorescence and hydrostatic pressure to study differences between these states. Pressure shifts the thermodynamic equilibrium between the two states. The estimated volume difference was 5 mL/mol, indicating a local conformational switch. The estimated free energy difference was 7.0 kJ/mol: high enough to keep the quenched state population low under normal conditions, but low enough to switch in a controlled way. These properties are physiologically relevant properties, because they guarantee efficient light harvesting, while at the same time maintaining the capacity to switch to a quenched state. These results indicate that conformational changes of LHCII can play an important role in NPQ.

KW - nonphotochemical energy-dissipation

KW - chlorophyll-protein complex

KW - photosystem-ii

KW - green plants

KW - chloroplast membranes

KW - excitation dynamics

KW - antenna complex

KW - molecular-basis

KW - lhcii

KW - absorption

U2 - 10.1021/jp070573z

DO - 10.1021/jp070573z

M3 - Article

VL - 111

SP - 7631

EP - 7637

JO - The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical

JF - The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical

SN - 1520-6106

IS - 26

ER -