The Antisense RNA As1_flv4 in the Cyanobacterium Synechocystis sp. PCC 6803 Prevents Premature Expression of the flv4-2 Operon upon Shift in Inorganic Carbon Supply

Eisenhut, Marion; Georg, Jens; Klähn, Stephan; Sakurai, Isamu; Mustila, Henna; Zhang, Pengpeng; Hess, Wolfgang R.; Aro, Eva‐Mari

doi:10.1074/jbc.m112.391755

Cited by 76 publications

(62 citation statements)

References 60 publications

(114 reference statements)

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“…In addition, increased levels were detected for 18 noncoding and antisense RNAs and decreased levels were detected for four antisense RNAs (Supplemental Table S2). Among the latter are the antisense RNAs to flv4 (sll0217), consistent with the relatively decreased mRNA level of flv4 (Table II), supporting the control function of this antisense RNA (Eisenhut et al, 2012). Interestingly, ssr2016 was found among the genes with increased transcript levels.…”

Section: Gene Expression Changesmentioning

confidence: 70%

The Gene sml0013 of Synechocystis Species Strain PCC 6803 Encodes for a Novel Subunit of the NAD(P)H Oxidoreductase or Complex I That Is Ubiquitously Distributed among Cyanobacteria

Schwarz

Schubert²,

Georg

et al. 2013

Plant Physiology

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The NAD(P)H oxidoreductase or complex I (NDH1) complex participates in many processes such as respiration, cyclic electron flow, and inorganic carbon concentration in the cyanobacterial cell. Despite immense progress in our understanding of the structure-function relation of the cyanobacterial NDH1 complex, the subunits catalyzing NAD(P)H docking and oxidation are still missing. The gene sml0013 of Synechocystis 6803 encodes for a small protein of unknown function for which homologs exist in all completely known cyanobacterial genomes. The protein exhibits weak similarities to the NDH-dependent flow6 (NDF6) protein, which was reported from Arabidopsis (Arabidopsis thaliana) chloroplasts as a NDH subunit. An sml0013 inactivation mutant of Synechocystis 6803 was generated and characterized. It showed only weak differences regarding growth and pigmentation in various culture conditions; most remarkably, it exhibited a glucose-sensitive phenotype in the light. The genome-wide expression pattern of the Dsml0013::Km mutant was almost identical to the wild type when grown under high CO 2 conditions as well as after shifts to low CO 2 conditions. However, measurements of the photosystem I redox kinetic in cells of the Dsml0013::Km mutant revealed differences, such as a decreased capability of cyclic electron flow as well as electron flow into respiration in comparison with the wild type. These results suggest that the Sml0013 protein (named NdhP) represents a novel subunit of the cyanobacterial NDH1 complex, mediating its coupling either to the respiratory or the photosynthetic electron flow.

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Section: Gene Expression Changesmentioning

confidence: 70%

The Gene sml0013 of Synechocystis Species Strain PCC 6803 Encodes for a Novel Subunit of the NAD(P)H Oxidoreductase or Complex I That Is Ubiquitously Distributed among Cyanobacteria

Schwarz

Schubert²,

Georg

et al. 2013

Plant Physiology

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“…Flv4 and Flv2 are suggested to mediate the electron transfer from PSII, very likely having a photoprotective role that comes into play around noon (48). The antisense RNA as_flv4 regulates the gene expression of flv4 and flv2, carried in the flv4-sll0218-flv2 operon (49). In this study, the amount of as_flv4 rose rapidly as soon as the light was turned on, whereas the abundance of flv4 target mRNA was anticorrelated with this rise, indicating a negative role of as_flv4 in flv4 mRNA stability.…”

Section: Resultsmentioning

confidence: 99%

Daily Expression Pattern of Protein-Encoding Genes and Small Noncoding RNAs in Synechocystis sp. Strain PCC 6803

Beck

Hertel

Rediger

et al. 2014

Appl Environ Microbiol

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“…PCC 6803, in which the transition from CO 2 -saturated to CO 2 -limited photosynthesis appeared to induce AEF, has four flv genes in its genome: flv1 (sll1521), flv2 (sll0219), flv3 (sll0550), and flv4 (sll0217). The activity of isozymes FLV2 and FLV4 seems to increase in response to low-[CO 2 ] conditions (Zhang et al, 2009;Eisenhut et al, 2012). A double mutant deficient in flv1 and flv3 showed the same response of Y(II) to the transition from CO 2 -saturated to CO 2 -limited photosynthesis as wild-type Synechocystis sp.…”

mentioning

confidence: 85%

FLAVODIIRON2 and FLAVODIIRON4 Proteins Mediate an Oxygen-Dependent Alternative Electron Flow in Synechocystis sp. PCC 6803 under CO2-Limited Conditions

et al. 2014

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(A.M., C.M.) This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO 2 -limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO 2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO 2 -limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADHdependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO 2 are not available.In photosynthesis, photon energy absorbed by PSI and PSII in thylakoid membranes oxidizes the reaction center chlorophylls (Chls), P700 in PSI and P680 in PSII, and drives the photosynthetic electron transport (PET) system. In PSII, water is oxidized to oxygen as the oxidized P680 accepts electrons from water. These electrons then reduce the cytochrome b 6 /f complex through plastoquinone (PQ) in the thylakoid membranes. Photooxidized P700 in PSI accepts electrons from the reduced cytochrome b 6 /f complex through plastocyanin or cytochrome c 6 . Electrons released in the photooxidation of P700 are used to produce NADPH through ferredoxin and ferredoxin NADP + reductase. Thus, electrons flow from water to NADPH in the so-called photosynthetic linear electron flow (LEF). Importantly, LEF induces a proton gradient across the thylakoid membranes, which provides the driving force for ATP production by ATP synthases in the thylakoid membranes. NADPH and ATP serve as chemical energy donors in the photosynthetic carbon reduction cycle (Calvin cycle).It recently has been proposed that, in cyanobacteria, the photorespiratory carbon oxidation cycle (photorespiration) functions simultaneously with the Calvin cycle to recover carbon for the regeneration of ribulose-1,5-bisphosphate, one of the substrates of Rubisco (Hagemann et al., 2013). Rubisco catalyzes the primary reactions of carbon reduction as well as oxidation cycles. However, the presence of a specific carbon concentration mechan...

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The Antisense RNA As1_flv4 in the Cyanobacterium Synechocystis sp. PCC 6803 Prevents Premature Expression of the flv4-2 Operon upon Shift in Inorganic Carbon Supply

Cited by 76 publications

References 60 publications

The Gene sml0013 of Synechocystis Species Strain PCC 6803 Encodes for a Novel Subunit of the NAD(P)H Oxidoreductase or Complex I That Is Ubiquitously Distributed among Cyanobacteria

The Gene sml0013 of Synechocystis Species Strain PCC 6803 Encodes for a Novel Subunit of the NAD(P)H Oxidoreductase or Complex I That Is Ubiquitously Distributed among Cyanobacteria

Daily Expression Pattern of Protein-Encoding Genes and Small Noncoding RNAs in Synechocystis sp. Strain PCC 6803

FLAVODIIRON2 and FLAVODIIRON4 Proteins Mediate an Oxygen-Dependent Alternative Electron Flow in Synechocystis sp. PCC 6803 under CO2-Limited Conditions

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