Mechanism of downregulation of photosystem I content under high-light conditions in the cyanobacterium Synechocystis sp. PCC 6803

Microbiology ◽  
2009 ◽  
Vol 155 (3) ◽  
pp. 989-996 ◽  
Author(s):  
Masayuki Muramatsu ◽  
Kintake Sonoike ◽  
Yukako Hihara
Keyword(s):  
Photosystem I ◽  
Regulatory Mechanism ◽  
Acid Synthesis ◽  
Chlorophyll Synthesis ◽  
High Light ◽  
Reaction Centre ◽  
Light Conditions ◽  
Aminolaevulinic Acid ◽  
Genes Encoding ◽  
Pcc 6803

Downregulation of photosystem I (PSI) content is an essential process for cyanobacteria to grow under high-light (HL) conditions. In a pmgA (sll1968) mutant of Synechocystis sp. PCC 6803, the levels of PSI content, chlorophyll and transcripts of the psaAB genes encoding reaction-centre subunits of PSI could not be maintained low during HL incubation, although the causal relationship among these phenotypes remains unknown. In this study, we modulated the activity of psaAB transcription or that of chlorophyll synthesis to estimate their contribution to the regulation of PSI content under HL conditions. Analysis of the psaAB-OX strain, in which the psaAB genes were overexpressed under HL conditions, revealed that the amount of psaAB transcript could not affect PSI content by itself. Suppression of chlorophyll synthesis by an inhibitor, laevulinic acid, in the pmgA mutant revealed that chlorophyll availability could be a determinant of PSI content under HL. It was also suggested that chlorophyll content under HL conditions is mainly regulated at the level of 5-aminolaevulinic acid synthesis. We conclude that, upon the shift to HL conditions, activities of psaAB transcription and of 5-aminolaevulinic acid synthesis are strictly downregulated by regulatory mechanism(s) independent of PmgA during the first 6 h, and then a PmgA-mediated regulatory mechanism becomes active after 6 h onward of HL incubation to maintain these activities at a low level.

scholarly journals Coordinated High-Light Response of Genes Encoding Subunits of Photosystem I Is Achieved by AT-Rich Upstream Sequences in the Cyanobacterium Synechocystis sp. Strain PCC 6803

2007 ◽  
Vol 189 (7) ◽  
pp. 2750-2758 ◽  
Author(s):  
Masayuki Muramatsu ◽  
Yukako Hihara
Keyword(s):  
Photosystem I ◽  
Promoter Region ◽  
Promoter Activity ◽  
Light Response ◽  
High Light ◽  
Light Conditions ◽  
Low Light ◽  
Genes Encoding ◽  
Responsive Element ◽  
Pcc 6803

ABSTRACT Genes encoding subunits of photosystem I (PSI genes) in the cyanobacterium Synechocystis sp. strain PCC 6803 are actively transcribed under low-light conditions, whereas their transcription is coordinately and rapidly down-regulated upon the shift to high-light conditions. In order to identify the molecular mechanism of the coordinated high-light response, we searched for common light-responsive elements in the promoter region of PSI genes. First, the precise architecture of the psaD promoter was determined and compared with the previously identified structure of the psaAB promoter. One of two promoters of the psaAB genes (P1) and of the psaD gene (P2) possessed an AT-rich light-responsive element located just upstream of the basal promoter region. These sequences enhanced the basal promoter activity under low-light conditions, and their activity was transiently suppressed upon the shift to high-light conditions. Subsequent analysis of psaC, psaE, psaK1, and psaLI promoters revealed that their light response was also achieved by AT-rich sequences located at the −70 to −46 region. These results clearly show that AT-rich upstream elements are responsible for the coordinated high-light response of PSI genes dispersed throughout Synechocystis genome.

scholarly journals The Response Regulator RpaB Binds to the Upstream Element of Photosystem I Genes To Work for Positive Regulation under Low-Light Conditions in Synechocystis sp. Strain PCC 6803

2008 ◽  
Vol 191 (5) ◽  
pp. 1581-1586 ◽  
Author(s):  
Yurie Seino ◽  
Tomoko Takahashi ◽  
Yukako Hihara
Keyword(s):  
Photosystem I ◽  
Promoter Activity ◽  
Response Regulator ◽  
Core Promoter ◽  
High Light ◽  
Light Conditions ◽  
Low Light ◽  
Positive Regulation ◽  
Upstream Element ◽  
Pcc 6803

ABSTRACT The coordinated high-light response of genes encoding subunits of photosystem I (PSI) is achieved by the AT-rich region located just upstream of the core promoter in Synechocystis sp. strain PCC 6803. The upstream element enhances the basal promoter activity under low-light conditions, whereas this positive regulation is lost immediately after the shift to high-light conditions. In this study, we focused on a high-light regulatory 1 (HLR1) sequence included in the upstream element of every PSI gene examined. A gel mobility shift assay revealed that a response regulator RpaB binds to the HLR1 sequence in PSI promoters. Base substitution in the HLR1 sequence or decrease in copy number of the rpaB gene resulted in decrease in the promoter activity of PSI genes under low-light conditions. These observations suggest that RpaB acts as a transcriptional activator for PSI genes. It is likely that RpaB binds to the HLR1 sequence under low-light conditions and works for positive regulation of PSI genes and for negative regulation of high-light-inducible genes depending on the location of the HLR1 sequence within target promoters.

scholarly journals RpaA Regulates the Accumulation of Monomeric Photosystem I and PsbA under High Light Conditions in Synechocystis sp. PCC 6803

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e45139 ◽  
Author(s):  
Waqar Majeed ◽  
Yan Zhang ◽  
Yong Xue ◽  
Saurabh Ranade ◽  
Ryan Nastashia Blue ◽  
...  
Keyword(s):  
Photosystem I ◽  
High Light ◽  
Light Conditions ◽  
Synechocystis Sp ◽  
Pcc 6803

scholarly journals The High Light-Inducible Polypeptides Stabilize Trimeric Photosystem I Complex under High Light Conditions in Synechocystis PCC 6803

2008 ◽  
Vol 147 (3) ◽  
pp. 1239-1250 ◽  
Author(s):  
Qiang Wang ◽  
Saowarath Jantaro ◽  
Bingshe Lu ◽  
Waqar Majeed ◽  
Marian Bailey ◽  
...  
Keyword(s):  
Photosystem I ◽  
High Light ◽  
Light Conditions ◽  
Synechocystis Pcc 6803 ◽  
Photosystem I Complex ◽  
Pcc 6803

Inhibition of chlorophyll synthesis in Hordeum vulgare by 3-amino 2,3-dihydrobenzoic acid (gabaculin)

1985 ◽  
Vol 5 (9) ◽  
pp. 775-781 ◽  
Author(s):  
Corinne M. Hill ◽  
Sharon A. Pearson ◽  
Arnold J. Smith ◽  
Lyndon J. Rogers
Keyword(s):  
Hordeum Vulgare ◽  
Potent Inhibitor ◽  
Acid Synthesis ◽  
Chlorophyll Synthesis ◽  
Dual Inhibitor ◽  
Aminolaevulinic Acid ◽  
Acid Dehydratase ◽  
Leaf Segments ◽  
Chlorophyll Formation ◽  
Aminolaevulinic Acid Dehydratase

Gabaculin (3-amino 2,3-dihydrobenzoic acid) is shown to be a very potent inhibitor of chlorophyll formation in Hordeum vulgate. Exposure of leaf segments to 30/μM gabaculin results in an 80% inhibition of chlorophyll synthesis, and this is paralleled by a decrease in carotenoid. Dual-inhibitor studies with dioxoheptanoic acid, which is an inhibitor of δ-aminolaevulinic acid dehydratase, show that gabaculin inhibits an earlier step than dioxoheptanoic acid and affects δ-aminolaevulinic acid synthesis rather than its subsequent metabolism.

scholarly journals The ricefaded green leaflocus encodes protochlorophyllide oxidoreductase B and is essential for chlorophyll synthesis under high light conditions

2013 ◽  
Vol 74 (1) ◽  
pp. 122-133 ◽  
Author(s):  
Yasuhito Sakuraba ◽  
Md Lutfor Rahman ◽  
Sung-Hwan Cho ◽  
Ye-Sol Kim ◽  
Hee-Jong Koh ◽  
...  
Keyword(s):  
Chlorophyll Synthesis ◽  
High Light ◽  
Light Conditions ◽  
Protochlorophyllide Oxidoreductase

scholarly journals Photosystem II antenna modules CP43 and CP47 do not form a stable ‘no reaction centre complex’ in the cyanobacterium Synechocystis sp. PCC 6803

2022 ◽  
Author(s):  
Martina Bečková ◽  
Roman Sobotka ◽  
Josef Komenda
Keyword(s):  
Photosystem Ii ◽  
High Light ◽  
Oxygenic Photosynthesis ◽  
Reaction Centre ◽  
Wild Type ◽  
Migration Patterns ◽  
Separate Protein ◽  
Antenna Module ◽  
D2 Protein ◽  
Pcc 6803

AbstractThe repair of photosystem II is a key mechanism that keeps the light reactions of oxygenic photosynthesis functional. During this process, the PSII central subunit D1 is replaced with a newly synthesized copy while the neighbouring CP43 antenna with adjacent small subunits (CP43 module) is transiently detached. When the D2 protein is also damaged, it is degraded together with D1 leaving both the CP43 module and the second PSII antenna module CP47 unassembled. In the cyanobacterium Synechocystis sp. PCC 6803, the released CP43 and CP47 modules have been recently suggested to form a so-called no reaction centre complex (NRC). However, the data supporting the presence of NRC can also be interpreted as a co-migration of CP43 and CP47 modules during electrophoresis and ultracentrifugation without forming a mutual complex. To address the existence of NRC, we analysed Synechocystis PSII mutants accumulating one or both unassembled antenna modules as well as Synechocystis wild-type cells stressed with high light. The obtained results were not compatible with the existence of a stable NRC since each unassembled module was present as a separate protein complex with a mutually similar electrophoretic mobility regardless of the presence of the second module. The non-existence of NRC was further supported by isolation of the His-tagged CP43 and CP47 modules from strains lacking either D1 or D2 and their migration patterns on native gels.

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