The role of theSynechocystissp. PCC 6803 homolog of the circadian clock output regulator RpaA in day-night transitions

2018 ◽  
Vol 110 (5) ◽  
pp. 847-861 ◽  
Author(s):  
Christin Köbler ◽  
Siri-Jasmin Schultz ◽  
Dominik Kopp ◽  
Karsten Voigt ◽  
Annegret Wilde
Keyword(s):  
Circadian Clock ◽  
Circadian Clock Output ◽  
Pcc 6803

scholarly journals Global Analysis of Circadian Expression in the Cyanobacterium Synechocystis sp. Strain PCC 6803

2005 ◽  
Vol 187 (6) ◽  
pp. 2190-2199 ◽  
Author(s):  
Ken-ichi Kucho ◽  
Kazuhisa Okamoto ◽  
Yuka Tsuchiya ◽  
Satoshi Nomura ◽  
Mamoru Nango ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Dna Microarrays ◽  
Global Analysis ◽  
Bacterial Species ◽  
Physiological State ◽  
Expression Patterns ◽  
Main Role ◽  
Circadian Expression ◽  
Pcc 6803

ABSTRACT Cyanobacteria are the only bacterial species found to have a circadian clock. We used DNA microarrays to examine circadian expression patterns in the cyanobacterium Synechocystis sp. strain PCC 6803. Our analysis identified 54 (2%) and 237 (9%) genes that exhibited circadian rhythms under stringent and relaxed filtering conditions, respectively. The expression of most cycling genes peaked around the time of transition from subjective day to night, suggesting that the main role of the circadian clock in Synechocystis is to adjust the physiological state of the cell to the upcoming night environment. There were several chromosomal regions where neighboring genes were expressed with similar circadian patterns. The physiological functions of the cycling genes were diverse and included a wide variety of metabolic pathways, membrane transport, and signal transduction. Genes involved in respiration and poly(3-hydroxyalkanoate) synthesis showed coordinated circadian expression, suggesting that the regulation is important for the supply of energy and carbon source in the night. Genes involved in transcription and translation also followed circadian cycling patterns. These genes may be important for output of the rhythmic information generated by the circadian clock. Our findings provided critical insights into the importance of the circadian clock on cellular physiology and the mechanism of clock-controlled gene regulation.

scholarly journals Homologs of Circadian Clock Proteins Impact the Metabolic Switch Between Light and Dark Growth in the Cyanobacterium Synechocystis sp. PCC 6803

2021 ◽  
Vol 12 ◽  
Author(s):  
Nina M. Scheurer ◽  
Yogeswari Rajarathinam ◽  
Stefan Timm ◽  
Christin Köbler ◽  
Joachim Kopka ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Response Regulator ◽  
Metabolic Switch ◽  
Carbon And Nitrogen ◽  
Clock Proteins ◽  
Genes Encoding ◽  
Carbon And Nitrogen Metabolism ◽  
Circadian Clock Proteins ◽  
Pcc 6803

The putative circadian clock system of the facultative heterotrophic cyanobacterial strain Synechocystis sp. PCC 6803 comprises the following three Kai-based systems: a KaiABC-based potential oscillator that is linked to the SasA-RpaA two-component output pathway and two additional KaiBC systems without a cognate KaiA component. Mutants lacking the genes encoding the KaiAB1C1 components or the response regulator RpaA show reduced growth in light/dark cycles and do not show heterotrophic growth in the dark. In the present study, the effect of these mutations on central metabolism was analyzed by targeted and non-targeted metabolite profiling. The strongest metabolic changes were observed in the dark in ΔrpaA and, to a lesser extent, in the ΔkaiAB1C1 mutant. These observations included the overaccumulation of 2-phosphoglycolate, which correlated with the overaccumulation of the RbcL subunit in the mutants, and taken together, these data suggest enhanced RubisCO activity in the dark. The imbalanced carbon metabolism in the ΔrpaA mutant extended to the pyruvate family of amino acids, which showed increased accumulation in the dark. Hence, the deletion of the response regulator rpaA had a more pronounced effect on metabolism than the deletion of the kai genes. The larger impact of the rpaA mutation is in agreement with previous transcriptomic analyses and likely relates to a KaiAB1C1-independent function as a transcription factor. Collectively, our data demonstrate an important role of homologs of clock proteins in Synechocystis for balanced carbon and nitrogen metabolism during light-to-dark transitions.

scholarly journals Homologs of circadian clock proteins impact the metabolic switch between light and dark growth in the cyanobacterium Synechocystis sp. PCC 6803

2021 ◽  
Author(s):  
Nina M. Scheurer ◽  
Yogeswari Rajarathinam ◽  
Stefan Timm ◽  
Christin Köbler ◽  
Joachim Kopka ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Response Regulator ◽  
Metabolic Switch ◽  
Carbon And Nitrogen ◽  
Clock Proteins ◽  
Genes Encoding ◽  
Carbon And Nitrogen Metabolism ◽  
Circadian Clock Proteins ◽  
Pcc 6803

AbstractThe putative circadian clock system of the facultative heterotrophic cyanobacterial strain Synechocystis sp. PCC 6803 comprises the following three Kai-based systems: a KaiABC-based potential oscillator that is linked to the SasA-RpaA two-component output pathway and two additional KaiBC systems without a cognate KaiA component. Mutants lacking the genes encoding the KaiAB1C1 components or the response regulator RpaA show reduced growth in light/dark cycles and do not show heterotrophic growth in the dark. In the present study, the effect of these mutations on central metabolism was analyzed by targeted and nontargeted metabolite profiling. The strongest metabolic changes were observed in the dark in ΔrpaA and, to a lesser extent, in the ΔkaiAB1C1 mutant. These observations included the overaccumulation of 2-phosphoglycolate, which correlated with the overaccumulation of the RbcL subunit in the mutants, and taken together, these data suggest enhanced RubisCO activity in the dark. The imbalanced carbon metabolism in the ΔrpaA mutant extended to the pyruvate family of amino acids, which showed increased accumulation in the dark. Hence, the deletion of the response regulator rpaA had a more pronounced effect on metabolism than the deletion of the kai genes. The larger impact of the rpaA mutation is in agreement with previous transcriptomic analyses and likely relates to a KaiAB1C1-independent function as a transcription factor. Collectively, our data demonstrate an important role of homologs of clock proteins in Synechocystis for balanced carbon and nitrogen metabolism during light-to-dark transitions.

scholarly journals Phosphorylation of GAPVD1 Is Regulated by the PER Complex and Linked to GAPVD1 Degradation

2021 ◽  
Vol 22 (7) ◽  
pp. 3787
Author(s):  
Hussam Ibrahim ◽  
Philipp Reus ◽  
Anna Katharina Mundorf ◽  
Anna-Lena Grothoff ◽  
Valerie Rudenko ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Transcriptional Repression ◽  
Small Gtpase ◽  
Main Role ◽  
Interacting Proteins ◽  
Casein Kinase 1 ◽  
Bona Fide ◽  
Kinetics Of

Repressor protein period (PER) complexes play a central role in the molecular oscillator mechanism of the mammalian circadian clock. While the main role of nuclear PER complexes is transcriptional repression, much less is known about the functions of cytoplasmic PER complexes. We found with a biochemical screen for PER2-interacting proteins that the small GTPase regulator GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1), which has been identified previously as a component of cytoplasmic PER complexes in mice, is also a bona fide component of human PER complexes. We show that in situ GAPVD1 is closely associated with casein kinase 1 delta (CSNK1D), a kinase that regulates PER2 levels through a phosphoswitch mechanism, and that CSNK1D regulates the phosphorylation of GAPVD1. Moreover, phosphorylation determines the kinetics of GAPVD1 degradation and is controlled by PER2 and a C-terminal autoinhibitory domain in CSNK1D, indicating that the regulation of GAPVD1 phosphorylation is a novel function of cytoplasmic PER complexes and might be part of the oscillator mechanism or an output function of the circadian clock.

scholarly journals A new insight into role of phosphoketolase pathway in Synechocystis sp. PCC 6803

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anushree Bachhar ◽  
Jiri Jablonsky
Keyword(s):  
In Silico Analysis ◽  
Bioinformatic Analysis ◽  
Phosphoglycerate Mutase ◽  
Phosphoketolase Pathway ◽  
Multi Level ◽  
Silico Analysis ◽  
Insight Into ◽  
Synechocystis Sp ◽  
Pcc 6803

AbstractPhosphoketolase (PKET) pathway is predominant in cyanobacteria (around 98%) but current opinion is that it is virtually inactive under autotrophic ambient CO2 condition (AC-auto). This creates an evolutionary paradox due to the existence of PKET pathway in obligatory photoautotrophs. We aim to answer the paradox with the aid of bioinformatic analysis along with metabolic, transcriptomic, fluxomic and mutant data integrated into a multi-level kinetic model. We discussed the problems linked to neglected isozyme, pket2 (sll0529) and inconsistencies towards the explanation of residual flux via PKET pathway in the case of silenced pket1 (slr0453) in Synechocystis sp. PCC 6803. Our in silico analysis showed: (1) 17% flux reduction via RuBisCO for Δpket1 under AC-auto, (2) 11.2–14.3% growth decrease for Δpket2 in turbulent AC-auto, and (3) flux via PKET pathway reaching up to 252% of the flux via phosphoglycerate mutase under AC-auto. All results imply that PKET pathway plays a crucial role under AC-auto by mitigating the decarboxylation occurring in OPP pathway and conversion of pyruvate to acetyl CoA linked to EMP glycolysis under the carbon scarce environment. Finally, our model predicted that PKETs have low affinity to S7P as a substrate.

scholarly journals Circadian clock protein Rev-erbα regulates neuroinflammation

2019 ◽  
Vol 116 (11) ◽  
pp. 5102-5107 ◽  
Author(s):  
Percy Griffin ◽  
Julie M. Dimitry ◽  
Patrick W. Sheehan ◽  
Brian V. Lananna ◽  
Chun Guo ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Microglial Activation ◽  
Time Of Day ◽  
Resting State Functional Connectivity ◽  
Promoter Regions ◽  
Clock Component ◽  
Glial Cultures ◽  
Inflammatory Phenotype

Circadian dysfunction is a common attribute of many neurodegenerative diseases, most of which are associated with neuroinflammation. Circadian rhythm dysfunction has been associated with inflammation in the periphery, but the role of the core clock in neuroinflammation remains poorly understood. Here we demonstrate that Rev-erbα, a nuclear receptor and circadian clock component, is a mediator of microglial activation and neuroinflammation. We observed time-of-day oscillation in microglial immunoreactivity in the hippocampus, which was disrupted in Rev-erbα−/− mice. Rev-erbα deletion caused spontaneous microglial activation in the hippocampus and increased expression of proinflammatory transcripts, as well as secondary astrogliosis. Transcriptomic analysis of hippocampus from Rev-erbα−/− mice revealed a predominant inflammatory phenotype and suggested dysregulated NF-κB signaling. Primary Rev-erbα−/− microglia exhibited proinflammatory phenotypes and increased basal NF-κB activation. Chromatin immunoprecipitation revealed that Rev-erbα physically interacts with the promoter regions of several NF-κB–related genes in primary microglia. Loss of Rev-erbα in primary astrocytes had no effect on basal activation but did potentiate the inflammatory response to lipopolysaccharide (LPS). In vivo, Rev-erbα−/− mice exhibited enhanced hippocampal neuroinflammatory responses to peripheral LPS injection, while pharmacologic activation of Rev-erbs with the small molecule agonist SR9009 suppressed LPS-induced hippocampal neuroinflammation. Rev-erbα deletion influenced neuronal health, as conditioned media from Rev-erbα–deficient primary glial cultures exacerbated oxidative damage in cultured neurons. Rev-erbα−/− mice also exhibited significantly altered cortical resting-state functional connectivity, similar to that observed in neurodegenerative models. Our results reveal Rev-erbα as a pharmacologically accessible link between the circadian clock and neuroinflammation.

Evidence for a dysfunction and disease-promoting role of the circadian clock in the diabetic retina

2021 ◽  
Vol 211 ◽  
pp. 108751
Author(s):  
Patrick Vancura ◽  
Laura Oebel ◽  
Simon Spohn ◽  
Ute Frederiksen ◽  
Kristina Schäfer ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Diabetic Retina

scholarly journals In Vivo Role of Phosphorylation of Cryptochrome 2 in the Mouse Circadian Clock

2014 ◽  
Vol 34 (24) ◽  
pp. 4464-4473 ◽  
Author(s):  
A. Hirano ◽  
N. Kurabayashi ◽  
T. Nakagawa ◽  
G. Shioi ◽  
T. Todo ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Cryptochrome 2
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