A binary redox control mode in gene expression and metabolism of plants
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE9235 | GEO | 2009/07/30
SECONDARY ACCESSION(S): PRJNA102839
REPOSITORIES: GEO
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Project description:To analyze the impact of photosynthetic redox signals, light sources with spectral qualities that preferentially excite either Photosystem I (PSI light) or Photosystem II (PSII light) were used. The light sources have been described in (Fey et al., 2005). Strong reduction and oxidation signals were induced by light shifts from PSI to PSII light (PSI-II) and the reverse light shift (PSII-I), respectivly. The acclimation responses were monitored at 0.5, 2, 8, and 48h after a light shift. Samples taken prior to changing the light quality (0h) served as control. Keywords: photosynthesis, redox regulation, light acclimation, retrograde signalling, long term response Experiments were performed with plant material corresponding to pools of at least 250-500 individuals of Arabidopsis thaliana (Col-0). To abtain healthy and unstressed plants, seedlings were initially grown for 21 days under white light (short day periods, 8-h light/16-h dark) on soil. Plants were then pre-acclimated to PSI-light for 3 days and reference samples were taken. Plants were then shifted to PSII light and tissue was harvested at the described time points. Similarly, samples were harvested before and after the reverse light shift. As additional control, plants acclimated to white light were also analyzed. RNA isolation: Leaf material was harvested and frozen in liquid N2 under the respective light source. Isolation of total RNA was performed as adapted from (Westhoff et al., 1991). Array analyses using the 3292-GST nylon array were performed as described earlier (Richly et al., 2003; Fey et al., 2005). Three independent experiments with different filters and independent cDNA probes were performed (for each timepoint).
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Project description:Series of 6 repetitions of hybridization of treatment (PSII) and control (PSI) each. Comparison of plants grown under PSII-specific light versus plants grown under PSI-specific light. E. Richly et al., EMBO Rep. 4 (2003), pp. 491–498 Keywords: repeat sample
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Project description:In photosynthesis, light is absorbed by the thylakoid embedded light harvesting pigment protein complexes (LHCs) that surround the photosynthetic reaction centers, photosystem II (PSII) and photosystem I (PSI). The distribution of light energy between the photosystems is balanced through state transitions1,2, which refer to the phosphorylation-dependent association of the loosely bound (L) LHCII antenna trimer either to PSII or PSI 3,4. Apart from phosphorylation, other mechanisms regulating state transitions have not been reported this far. In this study we demonstrate that lysine (Lys) acetylation of chloroplast proteins is a prerequisite for state transitions in Arabidopsis thaliana. Knock-out mutants lacking a chloroplast acetyltransferase NSI (At1g32070; AtNSI, SNAT) show selective decreases in the Lys acetylation status of several photosynthetic proteins including PSI, PSII and LHCII subunits. Fluorescence measurements revealed that changes in the wavelength of illumination do not cause state transitions in the nsi mutants even though their LHCII phosphorylation status is not defected. Furthermore, biochemical analyses of thylakoid proteins and protein complexes showed that nsi plants are not able to accumulate the phosphorylation dependent PSI-LHCII megacomplex. Our results manifest that Lys acetylation by NSI has an integral role in the regulation of state transitions in Arabidopsis.
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