In Vivo Sensitivity of Blue-Light-Dependent Signaling Mediated by AppA/PpsR or PrrB/PrrA in
            <i>Rhodobacter sphaeroides</i>

Metz, Sebastian; Jäger, Andreas; Klug, Gabriele

doi:10.1128/jb.00262-09

Cited by 16 publications

(30 citation statements)

References 27 publications

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“…As long as oxygen is available, Rhodobacter performs aerobic respiration. However, at intermediate oxygen tension blue light, even at low intensities, prevents AppA from binding to PpsR and photosynthesis genes are repressed (8,9), reducing the accumulation of the harmful singlet oxygen. The PrrB/PrrA two-component system senses the electron transport through the cbb3 oxidase and induces transcription of photosynthesis genes at very low oxygen tension or in the absence of oxygen (5,(10)(11)(12)(13).…”

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confidence: 99%

Regulation of bacterial photosynthesis genes by the small noncoding RNA PcrZ

Mank

Berghoff

Hermanns

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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The small RNA PcrZ (photosynthesis control RNA Z) of the facultative phototrophic bacterium Rhodobacter sphaeroides is induced upon a drop of oxygen tension with similar kinetics to those of genes for components of photosynthetic complexes. High expression of PcrZ depends on PrrA, the response regulator of the PrrB/ PrrA two-component system with a central role in redox regulation in R. sphaeroides. In addition the FnrL protein, an activator of some photosynthesis genes at low oxygen tension, is involved in redox-dependent expression of this small (s)RNA. Overexpression of full-length PcrZ in R. sphaeroides affects expression of a small subset of genes, most of them with a function in photosynthesis. Some mRNAs from the photosynthetic gene cluster were predicted to be putative PcrZ targets and results from an in vivo reporter system support these predictions. Our data reveal a negative effect of PcrZ on expression of its target mRNAs. Thus, PcrZ counteracts the redox-dependent induction of photosynthesis genes, which is mediated by protein regulators. Because PrrA directly activates photosynthesis genes and at the same time PcrZ, which negatively affects photosynthesis gene expression, this is one of the rare cases of an incoherent feed-forward loop including an sRNA. Our data identified PcrZ as a trans acting sRNA with a direct regulatory function in formation of photosynthetic complexes and provide a model for the control of photosynthesis gene expression by a regulatory network consisting of proteins and a small noncoding RNA.α-proteobacteria | protochlorophyllide reductase

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confidence: 99%

Regulation of bacterial photosynthesis genes by the small noncoding RNA PcrZ

Mank

Berghoff

Hermanns

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…More broadly speaking, it is also a new member of the family of blue light-photoactive proteins; bluegreen light is a ubiquitous environmental signal that activates a functionally diverse range of bacterial proteins, such as photoactive yellow protein (PYP) (26,27) and those containing LOV (28 -31) or BLUF domains (32)(33)(34)(35). Recent data available from genome sequencing as well as structural and functional characterization of these sensory proteins and their relatives have revealed that they share some general features in the structural basis of photoresponsiveness and signal transduction (36,37).…”

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confidence: 99%

Structural Determinants Underlying Photoprotection in the Photoactive Orange Carotenoid Protein of Cyanobacteria

Wilson

Kinney

Zwart

et al. 2010

Journal of Biological Chemistry

163

241

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The photoprotective processes of photosynthetic organisms involve the dissipation of excess absorbed light energy as heat. Photoprotection in cyanobacteria is mechanistically distinct from that in plants; it involves the orange carotenoid protein (OCP), a water-soluble protein containing a single carotenoid. The OCP is a new member of the family of blue light-photoactive proteins; blue-green light triggers the OCP-mediated photoprotective response. Here we report structural and functional characterization of the wild type and two mutant forms of the OCP, from the model organism Synechocystis PCC6803. The structural analysis provides high resolution detail of the carotenoid-protein interactions that underlie the optical properties of the OCP, unique among carotenoid-proteins in binding a single pigment per polypeptide chain. Collectively, these data implicate several key amino acids in the function of the OCP and reveal that the photoconversion and photoprotective responses of the OCP to blue-green light can be decoupled.The capture of light energy for oxygenic photosynthesis is arguably one of the most important metabolic processes on earth. It is also inherently risky; the absorbance of excess light energy beyond what can be used in photosynthesis can result in photooxidative damage to the organism. Consequently, photosynthetic organisms have evolved protective mechanisms to dissipate excess captured energy. In plants, one of these mechanisms involves the membrane-embedded chlorophyll-protein antenna of Photosystem II, the light-harvesting complex (for reviews, see Refs. 1-4). Under saturating light conditions, the decrease of the lumen pH activates the xanthophyll cycle (5, 6) and the protonation of PsbS, a Photosystem II subunit (7). Conformational changes in the light-harvesting complex, modifying the interaction between chlorophyll molecules and carotenoids and allowing thermal dissipation, are also involved in this mechanism (8 -10). Energy dissipation is accompanied by a diminution of Photosystem II-related fluorescence emission, also known as non-photochemical quenching (or NPQ; more specifically qE), which usually serves as a measure of the dissipation process.Although the photoprotective mechanism of plants is well studied, only recently have mechanisms for photoprotection in the cyanobacteria been discovered (11-17). One of these occurs at the water-soluble light-harvesting antenna (the phycobilisome) and involves a novel photosensory protein, the orange carotenoid protein (13, 18 -20). Most cyanobacterial species contain the OCP 5 (21,22), and in these organisms, it is constitutively expressed and is also up-regulated under extreme conditions, such as high light, iron starvation, and salt stress (18,(23)(24)(25). The OCP-mediated photoprotective mechanism is completely distinct from any known in plants and algae; it involves the absorption of blue-green light, which induces a shift in the absorbance properties of the OCP; visibly, the protein changes from orange to red (photoconversion). The structur...

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“…Current experimental data suggest that metabolismdependent chemotaxis may be more complex than previously thought, owing to differential gene expression in different environments. For example, PrrB/PrrA two-component system up-regulates photosynthesis in R. sphaeroides, and the expression is stimulated by low oxygen conditions [55]. This implies that at very low concentration, oxygen may no longer be an attractant, but may cause bacteria to start phototaxis.…”

Section: Discussionmentioning

confidence: 99%

A minimal model for metabolism-dependent chemotaxis inRhodobacter sphaeroides

Fan

Endres

2014

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Chemotaxis is vital cellular movement in response to environmental chemicals. Unlike the canonical chemotactic pathway in Escherichia coli , Rhodobacter sphaeroides has both transmembrane and cytoplasmic sensory clusters, with the latter possibly interacting with essential components in the electron transport system. However, the effect of the cytoplasmic sensor and the mechanism of signal integration from both sensory clusters remain unclear. Based on a minimal model of the chemotaxis pathway in this species, we show that signal integration at the motor level produces realistic chemotactic behaviour in line with experimental observations. Our model also suggests that the core pathway of R. sphaeroides , at least its ancestor, may represent a metabolism-dependent selective stopping strategy, which alone can steer cells to favourable environments. Our results not only clarify the potential roles of the two sensory clusters but also put in question the current definitions of attractants and repellents.

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In Vivo Sensitivity of Blue-Light-Dependent Signaling Mediated by AppA/PpsR or PrrB/PrrA in Rhodobacter sphaeroides

Abstract: Formation of photosynthesis complexes in

Cited by 16 publications

References 27 publications

Regulation of bacterial photosynthesis genes by the small noncoding RNA PcrZ

Regulation of bacterial photosynthesis genes by the small noncoding RNA PcrZ

Structural Determinants Underlying Photoprotection in the Photoactive Orange Carotenoid Protein of Cyanobacteria

A minimal model for metabolism-dependent chemotaxis inRhodobacter sphaeroides

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