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Discrete redox signaling pathways regulate photosynthetic light-harvesting and chloroplast gene transcription.

Allen JF, Santabarbara S, Allen CA, Puthiyaveetil S - PLoS ONE (2011)

Bottom Line: We asked whether CSK is also involved in regulation of absorbed light energy distribution by phosphorylation of light-harvesting complex II (LHC II).Chloroplast thylakoid membranes isolated from a CSK T-DNA insertion mutant and from wild-type Arabidopsis thaliana exhibit similar light- and redox-induced (32)P-labelling of LHC II and changes in 77 K chlorophyll fluorescence emission spectra, while room-temperature chlorophyll fluorescence emission transients from Arabidopsis leaves are perturbed by inactivation of CSK.The results indicate indirect, pleiotropic effects of reaction centre gene transcription on regulation of photosynthetic light-harvesting in vivo.

View Article: PubMed Central - PubMed

Affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom. j.f.allen@qmul.ac.uk

ABSTRACT
In photosynthesis in chloroplasts, two related regulatory processes balance the actions of photosystems I and II. These processes are short-term, post-translational redistribution of light-harvesting capacity, and long-term adjustment of photosystem stoichiometry initiated by control of chloroplast DNA transcription. Both responses are initiated by changes in the redox state of the electron carrier, plastoquinone, which connects the two photosystems. Chloroplast Sensor Kinase (CSK) is a regulator of transcription of chloroplast genes for reaction centres of the two photosystems, and a sensor of plastoquinone redox state. We asked whether CSK is also involved in regulation of absorbed light energy distribution by phosphorylation of light-harvesting complex II (LHC II). Chloroplast thylakoid membranes isolated from a CSK T-DNA insertion mutant and from wild-type Arabidopsis thaliana exhibit similar light- and redox-induced (32)P-labelling of LHC II and changes in 77 K chlorophyll fluorescence emission spectra, while room-temperature chlorophyll fluorescence emission transients from Arabidopsis leaves are perturbed by inactivation of CSK. The results indicate indirect, pleiotropic effects of reaction centre gene transcription on regulation of photosynthetic light-harvesting in vivo. A single, direct redox signal is transmitted separately to discrete transcriptional and post-translational branches of an integrated cytoplasmic regulatory system.

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Chlorophyll fluorescence emission by leaves of Arabidopsis thaliana at room temperature.Two days of light 1 treatment (before monitoring the room temperature variable chlorophyll fluorescence) are assiciated with an apparent state transition minus phenotype in CSK mutants. Figure 1a shows the time-course of variable chlorophyll fluorescence emission from leaves of Arabidopsis thaliana, which were grown in light 1. Illumination with light 2, which is absorbed primarily by photosystem II, initially increases chlorophyll fluorescence emission. Fluorescence then decreases, and one component of the decrease is the removal of light-harvesting capacity from photosystem II during the transition to state 2. Addition of light 1, absorbed primarily by photosystem I, causes an initial decrease in fluorescence and then a slow rise, as the light-harvesting capacity of photosystem II increases during the transition to state 1. The slow components attributable to the state 2 and state 1 transitions are seen in the wild type, but are absent from the CSK mutant. Figure 1b shows fluorescence emission from white light grown plants. Fm 1 and Fm 2 are maximal fluorescence at state 1 and state 2 respectively.
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pone-0026372-g001: Chlorophyll fluorescence emission by leaves of Arabidopsis thaliana at room temperature.Two days of light 1 treatment (before monitoring the room temperature variable chlorophyll fluorescence) are assiciated with an apparent state transition minus phenotype in CSK mutants. Figure 1a shows the time-course of variable chlorophyll fluorescence emission from leaves of Arabidopsis thaliana, which were grown in light 1. Illumination with light 2, which is absorbed primarily by photosystem II, initially increases chlorophyll fluorescence emission. Fluorescence then decreases, and one component of the decrease is the removal of light-harvesting capacity from photosystem II during the transition to state 2. Addition of light 1, absorbed primarily by photosystem I, causes an initial decrease in fluorescence and then a slow rise, as the light-harvesting capacity of photosystem II increases during the transition to state 1. The slow components attributable to the state 2 and state 1 transitions are seen in the wild type, but are absent from the CSK mutant. Figure 1b shows fluorescence emission from white light grown plants. Fm 1 and Fm 2 are maximal fluorescence at state 1 and state 2 respectively.

Mentions: Figure 1 shows the effects of actinic light 1 and light 2 on room-temperature chlorophyll fluorescence yield of one leaf, selected for size and thus signal amplitude, of Arabidopsis thaliana plants growing on compost. Figure 1 (a) shows results obtained with plants pre-adapted for 48 hours to growth in a red and far-red enriched light 1; figure 1 (b) shows results obtained with plants maintained in normal, low-irradiance, white light from fluorescent strips.


Discrete redox signaling pathways regulate photosynthetic light-harvesting and chloroplast gene transcription.

Allen JF, Santabarbara S, Allen CA, Puthiyaveetil S - PLoS ONE (2011)

Chlorophyll fluorescence emission by leaves of Arabidopsis thaliana at room temperature.Two days of light 1 treatment (before monitoring the room temperature variable chlorophyll fluorescence) are assiciated with an apparent state transition minus phenotype in CSK mutants. Figure 1a shows the time-course of variable chlorophyll fluorescence emission from leaves of Arabidopsis thaliana, which were grown in light 1. Illumination with light 2, which is absorbed primarily by photosystem II, initially increases chlorophyll fluorescence emission. Fluorescence then decreases, and one component of the decrease is the removal of light-harvesting capacity from photosystem II during the transition to state 2. Addition of light 1, absorbed primarily by photosystem I, causes an initial decrease in fluorescence and then a slow rise, as the light-harvesting capacity of photosystem II increases during the transition to state 1. The slow components attributable to the state 2 and state 1 transitions are seen in the wild type, but are absent from the CSK mutant. Figure 1b shows fluorescence emission from white light grown plants. Fm 1 and Fm 2 are maximal fluorescence at state 1 and state 2 respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198397&req=5

pone-0026372-g001: Chlorophyll fluorescence emission by leaves of Arabidopsis thaliana at room temperature.Two days of light 1 treatment (before monitoring the room temperature variable chlorophyll fluorescence) are assiciated with an apparent state transition minus phenotype in CSK mutants. Figure 1a shows the time-course of variable chlorophyll fluorescence emission from leaves of Arabidopsis thaliana, which were grown in light 1. Illumination with light 2, which is absorbed primarily by photosystem II, initially increases chlorophyll fluorescence emission. Fluorescence then decreases, and one component of the decrease is the removal of light-harvesting capacity from photosystem II during the transition to state 2. Addition of light 1, absorbed primarily by photosystem I, causes an initial decrease in fluorescence and then a slow rise, as the light-harvesting capacity of photosystem II increases during the transition to state 1. The slow components attributable to the state 2 and state 1 transitions are seen in the wild type, but are absent from the CSK mutant. Figure 1b shows fluorescence emission from white light grown plants. Fm 1 and Fm 2 are maximal fluorescence at state 1 and state 2 respectively.
Mentions: Figure 1 shows the effects of actinic light 1 and light 2 on room-temperature chlorophyll fluorescence yield of one leaf, selected for size and thus signal amplitude, of Arabidopsis thaliana plants growing on compost. Figure 1 (a) shows results obtained with plants pre-adapted for 48 hours to growth in a red and far-red enriched light 1; figure 1 (b) shows results obtained with plants maintained in normal, low-irradiance, white light from fluorescent strips.

Bottom Line: We asked whether CSK is also involved in regulation of absorbed light energy distribution by phosphorylation of light-harvesting complex II (LHC II).Chloroplast thylakoid membranes isolated from a CSK T-DNA insertion mutant and from wild-type Arabidopsis thaliana exhibit similar light- and redox-induced (32)P-labelling of LHC II and changes in 77 K chlorophyll fluorescence emission spectra, while room-temperature chlorophyll fluorescence emission transients from Arabidopsis leaves are perturbed by inactivation of CSK.The results indicate indirect, pleiotropic effects of reaction centre gene transcription on regulation of photosynthetic light-harvesting in vivo.

View Article: PubMed Central - PubMed

Affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom. j.f.allen@qmul.ac.uk

ABSTRACT
In photosynthesis in chloroplasts, two related regulatory processes balance the actions of photosystems I and II. These processes are short-term, post-translational redistribution of light-harvesting capacity, and long-term adjustment of photosystem stoichiometry initiated by control of chloroplast DNA transcription. Both responses are initiated by changes in the redox state of the electron carrier, plastoquinone, which connects the two photosystems. Chloroplast Sensor Kinase (CSK) is a regulator of transcription of chloroplast genes for reaction centres of the two photosystems, and a sensor of plastoquinone redox state. We asked whether CSK is also involved in regulation of absorbed light energy distribution by phosphorylation of light-harvesting complex II (LHC II). Chloroplast thylakoid membranes isolated from a CSK T-DNA insertion mutant and from wild-type Arabidopsis thaliana exhibit similar light- and redox-induced (32)P-labelling of LHC II and changes in 77 K chlorophyll fluorescence emission spectra, while room-temperature chlorophyll fluorescence emission transients from Arabidopsis leaves are perturbed by inactivation of CSK. The results indicate indirect, pleiotropic effects of reaction centre gene transcription on regulation of photosynthetic light-harvesting in vivo. A single, direct redox signal is transmitted separately to discrete transcriptional and post-translational branches of an integrated cytoplasmic regulatory system.

Show MeSH
Related in: MedlinePlus