The Mutant of <i>sll1961</i>, Which Encodes a Putative Transcriptional Regulator, Has a Defect in Regulation of Photosystem Stoichiometry in the Cyanobacterium <i>Synechocystis</i> sp. PCC 6803

Fujimori, Tamaki; Higuchi, Masakazu; Sato, Hanayo; Aiba, Hiroshi; Muramatsu, M; Hihara, Yukako; Sonoike, Kintake

doi:10.1104/pp.105.064782

Cited by 44 publications

(45 citation statements)

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“…1B). Similar growth inhibition after transient growth was observed under high-light conditions in a peroxiredoxin sll1621 mutant and sll1961 mutant, which is defective in regulation of photosystem stoichiometry (Fujimori et al, 2005). These facts imply that the growth inhibition is due to accumulation of photooxidative stresses.…”

Section: Disruption Of the Slr0846 Genesupporting

confidence: 52%

An Rrf2-Type Transcriptional Regulator Is Required for Expression of psaAB Genes in the Cyanobacterium Synechocystis sp. PCC 6803

et al. 2009

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Photosynthetic organisms must regulate photosystem stoichiometry (photosystem I-to-photosystem II ratio) under various light conditions. Transcriptional regulation of the psaAB genes is a critical process for this photoacclimation in cyanobacteria. In the course of our screening of transcriptional regulators in the cyanobacterium Synechocystis sp. PCC 6803, we found that chlorophyll accumulation was impaired in an Rrf2-type regulator Slr0846 mutant. DNA microarray and primer extension analyses showed that the expression of psaAB genes was markedly decreased in the mutant. Consistently, the mutant exhibited lower photosystem I-to-photosystem II ratio under normal light conditions, suggestive of decreased accumulation of the photosystem I reaction center. Gel-shift assay confirmed that the Slr0846 protein bound to a far upstream promoter region of psaAB. These phenotypes of the mutant varied substantially with light conditions. These results suggest that Slr0846 is a novel transcriptional regulator for optimal expression of psaAB.

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Section: Disruption Of the Slr0846 Genesupporting

confidence: 52%

An Rrf2-Type Transcriptional Regulator Is Required for Expression of psaAB Genes in the Cyanobacterium Synechocystis sp. PCC 6803

et al. 2009

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“…In cyanobacteria exposed to high-light (HL) conditions, the decrease in the amount of photosystem I (PSI) is more prominent than that of photosystem II (PSII), leading to the decrease of photosystem stoichiometry (PSI/PSII ratio) (7,13). This downregulation of PSI/ PSII ratio was shown to be indispensable for the survival under continuous HL conditions (3,6,22). In Synechocystis sp.…”

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confidence: 99%

Role of Multiple HLR1 Sequences in the Regulation of the Dual Promoters of thepsaABGenes inSynechocystissp. PCC 6803

et al. 2010

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Previously, we analyzed the promoter architecture of the psaAB genes encoding reaction center subunits of photosystem I (PSI) in the cyanobacterium Synechocystis sp. PCC 6803. There exist two promoters, P1 and P2, both of which show typical high-light (HL) response of PSI genes; their activities are high under low-light (LL) conditions but rapidly downregulated upon the shift to HL conditions. In this study, it was suggested that a response regulator RpaB binds to multiple high-light regulatory 1 (HLR1) sequences in the upstream region of the psaAB genes. We explored the regulatory role of cis-elements, including these HLR1 sequences on the individual activity of P1 and P2. Under LL conditions, the most influential cis-element is HLR1C (؊62 to ؊45, relative to the transcriptional starting point of P1) working for positive regulation of P1. The other HLR1 sequences also affect the promoter activity under LL conditions; HLR1A (؊255 to ؊238) is involved in repression of P1, whereas HLR1B (؊153 to ؊126) works for activation of P2. Upon the shift to HL conditions, regulation via HNE2 located within the region from ؊271 to ؊177 becomes active in order to downregulate both P1 and P2 activities. A positive effect of HLR1B on P2 may persist under HL. These results suggest that cis-elements, including multiple HLR1 sequences, differently regulate the activities of dual promoters of the psaAB genes to achieve the fine-tuning of the gene expression.Regulation of the amount of photosystem reaction center complexes is important for photosynthetic organisms to acclimate to different light environments. In cyanobacteria exposed to high-light (HL) conditions, the decrease in the amount of photosystem I (PSI) is more prominent than that of photosystem II (PSII), leading to the decrease of photosystem stoichiometry (PSI/PSII ratio) (7, 13). This downregulation of PSI/ PSII ratio was shown to be indispensable for the survival under continuous HL conditions (3,6,22). In Synechocystis sp. PCC 6803, genes encoding PSI subunits (PSI genes) are actively transcribed under low-light (LL) conditions, whereas their transcription is coordinately and strictly downregulated upon the shift to HL conditions preceding the decrease in protein level (5,8,9,14,21,23). We analyzed the architecture of PSI promoters and found that a high light regulatory 1 (HLR1) sequence located just upstream of the core promoter region is responsible for the coordinated HL response (15,16,19). The HLR1 sequence was initially identified by Eriksson et al. (2) as a common sequence located upstream of HL-inducible genes such as psbA2, psbA3, hliA, and nblA in Synechocystis sp. PCC 6803. Later, RpaB (Slr0947, Ycf27, and Rre26) response regulator was reported to bind to the HLR1 sequence of hliB in Synechocystis sp. PCC 6803 (11) and of rpoD3 in Synechococcus elongatus PCC 7942 (20) to work as a repressor under LL conditions. On the contrary, we observed that RpaB binds to the HLR1 sequence of PSI genes to work as an activator under LL conditions (19).The promoter archite...

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“…To cope with light fluctuations, cyanobacteria as well as algae and plants possess complex regulatory machinery to optimize the utilization of light energy and to protect photosynthetic apparatus against the damage induced by excessive light. This machinery involves the regulation of size and number of light-harvesting antennas (Anderson et al, 1995;Walters, 2005), dissipation of light energy by nonphotochemical quenching (El Bissati et al, 2000;Müller et al, 2001), redistribution of light energy between photosystems by state transition (Mullineaux and Emlyn-Jones, 2005;Fujimori et al, 2005), or adapting the capacity of carbon dioxide (CO 2 ) fixation (Demmig- Adams and Adams, 1992).…”

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Long-Term Acclimation of the Cyanobacterium Synechocystis sp. PCC 6803 to High Light Is Accompanied by an Enhanced Production of Chlorophyll That Is Preferentially Channeled to Trimeric Photosystem I

et al. 2012

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Cyanobacteria acclimate to high-light conditions by adjusting photosystem stoichiometry through a decrease of photosystem I (PSI) abundance in thylakoid membranes. As PSI complexes bind the majority of chlorophyll (Chl) in cyanobacterial cells, it is accepted that the mechanism controlling PSI level/synthesis is tightly associated with the Chl biosynthetic pathway. However, how Chl is distributed to photosystems under different light conditions remains unknown. Using radioactive labeling by 35 S and by 14 C combined with native/two-dimensional electrophoresis, we assessed the synthesis and accumulation of photosynthetic complexes in parallel with the synthesis of Chl in Synechocystis sp. PCC 6803 cells acclimated to different light intensities. Although cells acclimated to higher irradiances (150 and 300 mE m 22 s 21 ) exhibited markedly reduced PSI content when compared with cells grown at lower irradiances (10 and 40 mE m 22 s 21 ), they grew much faster and synthesized significantly more Chl, as well as both photosystems. Interestingly, even under high irradiance, almost all labeled de novo Chl was localized in the trimeric PSI, whereas only a weak Chl labeling in photosystem II (PSII) was accompanied by the intensive 35 S protein labeling, which was much stronger than in PSI. These results suggest that PSII subunits are mostly synthesized using recycled Chl molecules previously released during PSII repair-driven protein degradation. In contrast, most of the fresh Chl is utilized for synthesis of PSI complexes likely to maintain a constant level of PSI during cell proliferation.

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The Mutant of sll1961, Which Encodes a Putative Transcriptional Regulator, Has a Defect in Regulation of Photosystem Stoichiometry in the Cyanobacterium Synechocystis sp. PCC 6803

Cited by 44 publications

References 32 publications

An Rrf2-Type Transcriptional Regulator Is Required for Expression of psaAB Genes in the Cyanobacterium Synechocystis sp. PCC 6803

An Rrf2-Type Transcriptional Regulator Is Required for Expression of psaAB Genes in the Cyanobacterium Synechocystis sp. PCC 6803

Role of Multiple HLR1 Sequences in the Regulation of the Dual Promoters of thepsaABGenes inSynechocystissp. PCC 6803

Long-Term Acclimation of the Cyanobacterium Synechocystis sp. PCC 6803 to High Light Is Accompanied by an Enhanced Production of Chlorophyll That Is Preferentially Channeled to Trimeric Photosystem I

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