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 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 The E3 Ligases Spsb1 and Spsb4 Regulate RevErbα Degradation and Circadian Period

2019 ◽  
Vol 34 (6) ◽  
pp. 610-621 ◽  
Author(s):  
Tsedey Mekbib ◽  
Ting-Chung Suen ◽  
Aisha Rollins-Hairston ◽  
Jason P. DeBruyne
Keyword(s):  
Circadian Clock ◽  
Critical Role ◽  
Ubiquitin Proteasome System ◽  
E3 Ligases ◽  
Clock Proteins ◽  
Ubiquitin Proteasome ◽  
A Cell ◽  
Circadian Clock Proteins ◽  
The Stability

The time-dependent degradation of core circadian clock proteins is essential for the proper functioning of circadian timekeeping mechanisms that drive daily rhythms in gene expression and, ultimately, an organism’s physiology. The ubiquitin proteasome system plays a critical role in regulating the stability of most proteins, including the core clock components. Our laboratory developed a cell-based functional screen to identify ubiquitin ligases that degrade any protein of interest and have started screening for those ligases that degrade circadian clock proteins. This screen identified Spsb4 as a putative novel E3 ligase for RevErbα. In this article, we further investigate the role of Spsb4 and its paralogs in RevErbα stability and circadian rhythmicity. Our results indicate that the paralogs Spsb1 and Spsb4, but not Spsb2 and Spsb3, can interact with and facilitate RevErbα ubiquitination and degradation and regulate circadian clock periodicity.

scholarly journals Role of Multiple HLR1 Sequences in the Regulation of the Dual Promoters of the psaAB Genes in Synechocystis sp. PCC 6803

2010 ◽  
Vol 192 (15) ◽  
pp. 4031-4036 ◽  
Author(s):  
Tomoko Takahashi ◽  
Nanako Nakai ◽  
Masayuki Muramatsu ◽  
Yukako Hihara
Keyword(s):  
Response Regulator ◽  
High Light ◽  
Fine Tuning ◽  
Upstream Region ◽  
Starting Point ◽  
Genes Encoding ◽  
The Individual ◽  
Dual Promoters ◽  
Pcc 6803

ABSTRACT Previously, we analyzed the promoter architecture of the psaAB genes encoding reaction center subunits of photosystem I (PSI) in the cyanobacterium Synechocystis sp. PCC 6803. There exist two promoters, P1 and P2, both of which show typical high-light (HL) response of PSI genes; their activities are high under low-light (LL) conditions but rapidly downregulated upon the shift to HL conditions. In this study, it was suggested that a response regulator RpaB binds to multiple high-light regulatory 1 (HLR1) sequences in the upstream region of the psaAB genes. We explored the regulatory role of cis-elements, including these HLR1 sequences on the individual activity of P1 and P2. Under LL conditions, the most influential cis-element is HLR1C (−62 to −45, relative to the transcriptional starting point of P1) working for positive regulation of P1. The other HLR1 sequences also affect the promoter activity under LL conditions; HLR1A (−255 to −238) is involved in repression of P1, whereas HLR1B (−153 to −126) works for activation of P2. Upon the shift to HL conditions, regulation via HNE2 located within the region from −271 to −177 becomes active in order to downregulate both P1 and P2 activities. A positive effect of HLR1B on P2 may persist under HL. These results suggest that cis-elements, including multiple HLR1 sequences, differently regulate the activities of dual promoters of the psaAB genes to achieve the fine-tuning of the gene expression.

scholarly journals Circadian Clock Proteins in Prokaryotes: Hidden Rhythms?

2010 ◽  
Vol 1 ◽  
Author(s):  
Maria Loza-Correa ◽  
Laura Gomez-Valero ◽  
Carmen Buchrieser
Keyword(s):  
Circadian Clock ◽  
Clock Proteins ◽  
Circadian Clock Proteins

scholarly journals Attenuated SIRT1 Activity Leads to PER2 Cytoplasmic Localization and Dampens the Amplitude of Bmal1 Promoter-Driven Circadian Oscillation

2021 ◽  
Vol 15 ◽  
Author(s):  
Atsushige Ashimori ◽  
Yasukazu Nakahata ◽  
Toshiya Sato ◽  
Yuichiro Fukamizu ◽  
Takaaki Matsui ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Circadian Clock ◽  
Posttranslational Modifications ◽  
Cultured Cells ◽  
Circadian Oscillation ◽  
Clock Proteins ◽  
Circadian Clock Proteins ◽  
Circadian Physiology ◽  
And Behavior ◽  
Robust Systems

The circadian clock possesses robust systems to maintain the rhythm approximately 24 h, from cellular to organismal levels, whereas aging is known to be one of the risk factors linked to the alternation of circadian physiology and behavior. The amount of many metabolites in the cells/body is altered with the aging process, and the most prominent metabolite among them is the oxidized form of nicotinamide adenine dinucleotide (NAD+), which is associated with posttranslational modifications of acetylation and poly-ADP-ribosylation status of circadian clock proteins and decreases with aging. However, how low NAD+ condition in cells, which mimics aged or pathophysiological conditions, affects the circadian clock is largely unknown. Here, we show that low NAD+ in cultured cells promotes PER2 to be retained in the cytoplasm through the NAD+/SIRT1 axis, which leads to the attenuated amplitude of Bmal1 promoter-driven luciferase oscillation. We found that, among the core clock proteins, PER2 is mainly affected in its subcellular localization by NAD+ amount, and a higher cytoplasmic PER2 localization was observed under low NAD+ condition. We further found that NAD+-dependent deacetylase SIRT1 is the regulator of PER2 subcellular localization. Thus, we anticipate that the altered PER2 subcellular localization by low NAD+ is one of the complex changes that occurs in the aged circadian clock.

scholarly journals 2PT229 The regulation of cyanobacterial circadian clock proteins KaiB-KaiC interaction by ATP(The 50th Annual Meeting of the Biophysical Society of Japan)

2012 ◽  
Vol 52 (supplement) ◽  
pp. S143
Author(s):  
Risa Mutoh ◽  
Atsuhito Nishimura ◽  
So Yasui ◽  
Kiyoshi Onai ◽  
Masahiro Ishiura
Keyword(s):  
Circadian Clock ◽  
Annual Meeting ◽  
Clock Proteins ◽  
Biophysical Society ◽  
Circadian Clock Proteins

scholarly journals Relationship between HIF-1 and Circadian Clock Proteins in Obstructive Sleep Apnea Patients—Preliminary Study

2020 ◽  
Vol 9 (5) ◽  
pp. 1599 ◽  
Author(s):  
Agata Gabryelska ◽  
Marcin Sochal ◽  
Szymon Turkiewicz ◽  
Piotr Białasiewicz
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Circadian Clock ◽  
Protein Level ◽  
Hypoxia Inducible Factor ◽  
Apnea Hypopnea Index ◽  
Clock Proteins ◽  
Obstructive Sleep ◽  
Healthy Control ◽  
Circadian Clock Proteins

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia and associated with the disruption of circadian rhythm. The study aimed to assess the relationship between hypoxia-inducible factor (HIF) subunits, circadian clock proteins, and polysomnography (PSG) variables, in healthy individuals and severe OSA patients. The study included 20 individuals, who underwent PSG and were divided into severe OSA group (n = 10; AHI ≥ 30) and healthy control (n = 10; AHI < 5) based on apnea-hypopnea index (AHI). All participants had their peripheral blood collected in the evening before and the morning after the PSG. HIF-1α, HIF-1β, BMAL1, CLOCK, CRY1, and PER1 protein concertation measurements were performed using ELISA. In a multivariate general linear model with the concentration of all circadian clock proteins as dependent variables, evening HIF-1α protein level was the only significant covariant (p = 0.025). Corrected models were significant for morning and evening PER1 (p = 0.008 and p = 0.006, respectively), evening (p = 0.043), and evening BMAL protein level (p = 0.046). In corrected models, evening HIF-1α protein level had an influence only on the evening PER1 protein level. Results suggest that OSA patients are at risk for developing circadian clock disruption. This process might be mediated by subunit α of HIF-1, as its increased protein level is associated with overexpression of circadian clock proteins.

scholarly journals Synechocystis KaiC3 Displays Temperature- and KaiB-Dependent ATPase Activity and Is Important for Growth in Darkness

2019 ◽  
Vol 202 (4) ◽  
Author(s):  
Anika Wiegard ◽  
Christin Köbler ◽  
Katsuaki Oyama ◽  
Anja K. Dörrich ◽  
Chihiro Azai ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Circadian Clock ◽  
Atp Hydrolysis ◽  
Synechococcus Elongatus ◽  
Constant Darkness ◽  
Content Type ◽  
Clock Proteins ◽  
Pcc 7942 ◽  
Pcc 6803

ABSTRACT Cyanobacteria form a heterogeneous bacterial group with diverse lifestyles, acclimation strategies, and differences in the presence of circadian clock proteins. In Synechococcus elongatus PCC 7942, a unique posttranslational KaiABC oscillator drives circadian rhythms. ATPase activity of KaiC correlates with the period of the clock and mediates temperature compensation. Synechocystis sp. strain PCC 6803 expresses additional Kai proteins, of which KaiB3 and KaiC3 proteins were suggested to fine-tune the standard KaiAB1C1 oscillator. In the present study, we therefore characterized the enzymatic activity of KaiC3 as a representative of nonstandard KaiC homologs in vitro. KaiC3 displayed ATPase activity lower than that of the Synechococcus elongatus PCC 7942 KaiC protein. ATP hydrolysis was temperature dependent. Hence, KaiC3 is missing a defining feature of the model cyanobacterial circadian oscillator. Yeast two-hybrid analysis showed that KaiC3 interacts with KaiB3, KaiC1, and KaiB1. Further, KaiB3 and KaiB1 reduced in vitro ATP hydrolysis by KaiC3. Spot assays showed that chemoheterotrophic growth in constant darkness is completely abolished after deletion of ΔkaiAB1C1 and reduced in the absence of kaiC3. We therefore suggest a role for adaptation to darkness for KaiC3 as well as a cross talk between the KaiC1- and KaiC3-based systems. IMPORTANCE The circadian clock influences the cyanobacterial metabolism, and deeper understanding of its regulation will be important for metabolic optimizations in the context of industrial applications. Due to the heterogeneity of cyanobacteria, characterization of clock systems in organisms apart from the circadian model Synechococcus elongatus PCC 7942 is required. Synechocystis sp. strain PCC 6803 represents a major cyanobacterial model organism and harbors phylogenetically diverged homologs of the clock proteins, which are present in various other noncyanobacterial prokaryotes. By our in vitro studies we unravel the interplay of the multiple Synechocystis Kai proteins and characterize enzymatic activities of the nonstandard clock homolog KaiC3. We show that the deletion of kaiC3 affects growth in constant darkness, suggesting its involvement in the regulation of nonphotosynthetic metabolic pathways.

scholarly journals SnapShot: Circadian Clock Proteins

Cell ◽  
2008 ◽  
Vol 135 (2) ◽  
pp. 368-368.e1 ◽  
Author(s):  
Elizabeth E. Hamilton ◽  
Steve A. Kay
Keyword(s):  
Circadian Clock ◽  
Clock Proteins ◽  
Circadian Clock Proteins
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