Structure and function of photosystem I: interaction with its soluble electron carriers and external antenna systems

Fromme, Petra; Melkozernov, Alexander N.; Jordan, Patrick; Krauß, Norbert

doi:10.1016/s0014-5793(03)01124-4

Cited by 222 publications

(149 citation statements)

References 36 publications

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“…In order to alleviate the damaging effects of Fe limitation, photosynthetic organisms activate flavodoxin proteins as an electron carrier substitute for the more Fe-rich ferredoxin (56). In line with this, we observed the downregulation of ferredoxin proteins and upregulation of flavodoxin proteins in our Fe-limited chemostats.…”

Section: Discussionsupporting

confidence: 84%

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Yeung

D’Agostino

Poljak

et al. 2016

Appl Environ Microbiol

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The hepatotoxin microcystin (MCYST) is produced by a variety of freshwater cyanobacterial species, including Microcystis aeruginosa. Interestingly, MCYST-producing M. aeruginosa strains have been shown to outcompete their nontoxic counterparts under iron-limiting conditions. However, the reasons for this are unclear. Here we examined the proteomic response of M. aeruginosa PCC 7806 continuous cultures under different iron and growth regimes. Iron limitation was correlated with a global reduction in levels of proteins associated with energy metabolism and photosynthesis. These proteomic changes were consistent with physiological observations, including reduced chlorophyll a content and reduced cell size. While levels of MCYST biosynthesis proteins did not fluctuate during the study period, both intra-and extracellular toxin quotas were significantly higher under iron-limiting conditions. Our results support the hypothesis that intracellular MCYST plays a role in protecting the cell against oxidative stress. Further, we propose that extracellular MCYST may act as a signaling molecule, stimulating MCYST production under conditions of iron limitation and enhancing the fitness of bloom populations. IMPORTANCEMicrocystin production in water supply reservoirs is a global public health problem. Understanding the ecophysiology of hepatotoxic cyanobacteria, including their responses to the presence of key micronutrient metals such as iron, is central to managing harmful blooms. To our knowledge, this was the first study to examine proteomic and physiological changes occurring in M. aeruginosa continuous cultures under conditions of iron limitation at different growth rates. C yanobacteria ("blue-green algae") proliferate in warm stratified water bodies rich in nitrogen and phosphorus (1, 2). Cyanobacterial blooms can have a negative impact on the appearance, taste, and odor of water, and their subsequent decay can lead to oxygen depletion and fish kills (3). However, of greatest concern to public health is their production of potent toxins. Microcystis aeruginosa (Kützing) Lemmermann is a common bloom-forming cyanobacterial species that produces hepatotoxic microcystins (MCYSTs) (1). These nonribosomally synthesized peptides inhibit eukaryotic protein phosphatases, leading to liver necrosis in acute doses and hepatocellular carcinoma in chronic low doses (4, 5).There is strong evidence that the production of MCYST is a direct function of cell division (6). It is therefore not surprising that parameters affecting cyanobacterial growth rate (e.g., nutrients, trace metals, temperature, pH, and light) have been correlated with fluctuating MCYST levels in batch culture experiments (7-9).Recent molecular studies suggest that iron (Fe) and nitrogen (N) also play a role in regulating the expression of MCYST biosynthesis (mcy) genes. In M. aeruginosa, for example, the mcy promoter region contains binding sites for the ferric uptake regulator (Fur) and the global nitrogen regulator (NtcA) (10, 11). Despite these genetic clu...

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Section: Discussionsupporting

confidence: 84%

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Yeung

D’Agostino

Poljak

et al. 2016

Appl Environ Microbiol

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“…5), suggesting that the major component of the LHCP dimer band is LHCI. This is consistent with the idea that LHCI exists as a dimer (Fromme et al 2003). The band just above the LHCP dimer band, which is retained in the cao mutants, contains only Chl a and β-carotene, suggesting that it is CP43 and/or CP47 (data not shown).…”

supporting

confidence: 90%

Characterization of Chlorophyllide a Oxygenase (CAO) in Rice

et al. 2005

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“…Chlorophyll molecules universally exist in photosynthetic organisms and perform essential processes of harvesting light energy in the antenna systems and by driving electron transfer in the reaction centers (Fromme et al, 2003). According to the number of vinyl side chains, chlorophylls of oxygenic photosynthetic organisms are classified into two groups: 3,8-divinyl chlorophyll (divinyl chlorophyll) and 3-vinyl chlorophyll (monovinyl chlorophyll).…”

Section: Introductionmentioning

confidence: 99%

Identification of a Vinyl Reductase Gene for Chlorophyll Synthesis in Arabidopsis thaliana and Implications for the Evolution of Prochlorococcus Species

et al. 2005

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Chlorophyll metabolism has been extensively studied with various organisms, and almost all of the chlorophyll biosynthetic genes have been identified in higher plants. However, only the gene for 3,8-divinyl protochlorophyllide a 8-vinyl reductase (DVR), which is indispensable for monovinyl chlorophyll synthesis, has not been identified yet. In this study, we isolated an Arabidopsis thaliana mutant that accumulated divinyl chlorophyll instead of monovinyl chlorophyll by ethyl methanesulfonate mutagenesis. Map-based cloning of this mutant resulted in the identification of a gene (AT5G18660) that shows sequence similarity with isoflavone reductase genes. The mutant phenotype was complemented by the transformation with the wild-type gene. A recombinant protein encoded by AT5G18660 was expressed in Escherichia coli and found to catalyze the conversion of divinyl chlorophyllide to monovinyl chlorophyllide, thereby demonstrating that the gene encodes a functional DVR. DVR is encoded by a single copy gene in the A. thaliana genome. With the identification of DVR, finally all genes required for chlorophyll biosynthesis have been identified in higher plants. Analysis of the complete genome of A. thaliana showed that it has 15 enzymes encoded by 27 genes for chlorophyll biosynthesis from glutamyl-tRNAglu to chlorophyll b. Furthermore, identification of the DVR gene helped understanding the evolution of Prochlorococcus marinus, a marine cyanobacterium that is dominant in the open ocean and is uncommon in using divinyl chlorophylls. A DVR homolog was not found in the genome of P. marinus but found in the Synechococcus sp WH8102 genome, which is consistent with the distribution of divinyl chlorophyll in marine cyanobacteria of the genera Prochlorococcus and Synechococcus

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Structure and function of photosystem I: interaction with its soluble electron carriers and external antenna systems

Cited by 222 publications

References 36 publications

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Characterization of Chlorophyllide a Oxygenase (CAO) in Rice

Identification of a Vinyl Reductase Gene for Chlorophyll Synthesis in Arabidopsis thaliana and Implications for the Evolution of Prochlorococcus Species

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