The Bacterial Perspective on Circadian Clocks

Johnson, Carl Hirschie; Rust, Michael J.

doi:10.1007/978-3-030-72158-9_1

Cited by 8 publications

(6 citation statements)

References 108 publications

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“…Several years after the reports of circadian phenomena in Synechococcus RF-1, we and our collaborators began the analysis of circadian rhythmicity in the cyanobacterium Synechococcus elongatus PCC 7942 (hereafter S. elongatus ), which was a species for which genetic tools were available, and for which a luciferase reporter strain (P psbAI ::luxAB) had already been generated for the analysis of light intensity regulation of gene expression ( Kondo et al, 1993 ; Johnson & Xu, 2009 ). The availability of genetic tools and a robust luminescence reporter of rhythmic gene expression enabled spectacular progress on understanding the mechanism and adaptive significance of circadian rhythmicity in cyanobacteria, transforming S. elongatus into one of the best understood circadian model organisms ( Johnson et al, 2017 ; Chavan et al, 2021 ; Ito-Miwa et al, 2021 ; Johnson & Rust, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Synechocystis: A model system for expanding the study of cyanobacterial circadian rhythms

Zhao

Wang

et al. 2023

Front. Physiol.

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The study of circadian rhythms in bacteria was transformed by studies of the cyanobacterium Synechococcus elongatus. However, in a number of respects S. elongatus is atypical, and while those unusual characteristics were helpful for rapid progress in the past, another commonly used cyanobacterial species, Synechocystis sp. PCC 6803, may be more representative and therefore more productive for future insights into bacterial clock mechanisms. In the past, circadian studies of Synechocystis have suffered from not having an excellent reporter of circadian gene expression, but we introduce here a new luminescence reporter that rivals the reporters that have been used so successfully in S. elongatus. Using this new system, we generate for the first time in Synechocystis circadian period mutants resulting from point mutations. The temperature compensation and dark-pulse resetting that mediates entrainment to the environment is characterized. Moreover, we analyse the complex organization of clock genes in Synechocystis and identify which genes are essential for circadian rhythmicity and adaptive fitness for entrainment and optimal phase alignment to environmental cycles (and which genes are not). These developments will provide impetus for new approaches towards understanding daily timekeeping mechanisms in bacteria.

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Section: Introductionmentioning

confidence: 99%

Synechocystis: A model system for expanding the study of cyanobacterial circadian rhythms

Zhao

Wang

et al. 2023

Front. Physiol.

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“…These findings provide insights into the rational design of soft materials that can rhythmically transition between states with different material properties on a pre-determined schedule. Bottom-up construction of such materials, both in experiments as well as in silico , will provide an understanding of the general principles and mechanisms underlying how time-varying environments and time-keeping machineries shape the dynamic collective properties of living systems 2–4 with potential for application in soft robotics. 25…”

Section: Discussionmentioning

confidence: 99%

“…1 They are robust to time-varying environments 2 and often undergo dynamic changes in properties based on internal time-keeping machinery such as the cell cycle and the circadian clock. 3 Recent studies have also suggested the existence of “autonomous clocks” which can run independently to support living systems’ functions. 4 A mechanistic understanding of such biological systems can advance the engineering of new smart materials that can self-organize, self-stimulate, and evolve independently according to the application environment.…”

Section: Introductionmentioning

confidence: 99%

Sustained order–disorder transitions in a model colloidal system driven by rhythmic crosslinking

et al. 2022

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“…Circadian clocks arose during evolution to enable organisms, from cyanobacteria to plants and mammals, to tune their metabolism and bioprocesses to daily light/darkness cycles on Earth, and thereby optimize their fitness (Johnson and Rust, 2021; Shultzaberger et al, 2015). Much of what is known about the mechanisms behind circadian clocks in the case of cyanobacteria has been learned from investigations of unicellular organisms, primarily Synechococcus elongatus strain PCC 7942 (henceforth S. elongatus ).…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal coherence of circadian clocks and gating of differentiation inAnabaenafilaments

Arbel-Goren

Dassa

Zhitnitsky

et al. 2023

Preprint

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Circadian clock arrays in multicellular filaments of the heterocyst-forming cyanobacteriumAnabaenasp. strain PCC 7120 display remarkable spatio-temporal coherence under nitrogen-replete conditions. To shed light on the interplay between circadian clocks and the formation of developmental patterns, we followed the expression of a clock-controlled gene under nitrogen deprivation, at the level of individual cells. Our experiments showed that differentiation into heterocysts took place preferentially within a limited interval of the circadian clock cycle; that gene expression in different vegetative intervals along a developed filament was discoordinated; and that the circadian clock was active in individual heterocysts. Furthermore,Anabaenamutants lacking thekaiABCgenes encoding the circadian clock core components produced heterocysts but failed in diazotrophy. Therefore, genes related to some aspect of nitrogen fixation, rather than early or mid-heterocyst differentiation genes, are likely affected by the absence of the clock. A bioinformatics analysis supports the notion that RpaA may play a role as master regulator of clock outputs inAnabaena,the gating of differentiation by the circadian clock and the involvement of the clock in proper diazotrophic growth. Together, these results suggest that under nitrogen deficient conditions, the functional unit inAnabaenais reduced from a full filament under nitrogen-rich conditions, to the vegetative cell interval between heterocysts.

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The Bacterial Perspective on Circadian Clocks

Cited by 8 publications

References 108 publications

Synechocystis: A model system for expanding the study of cyanobacterial circadian rhythms

Synechocystis: A model system for expanding the study of cyanobacterial circadian rhythms

Sustained order–disorder transitions in a model colloidal system driven by rhythmic crosslinking

Spatio-temporal coherence of circadian clocks and gating of differentiation inAnabaenafilaments

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