<scp>KaiC</scp>‐like proteins contribute to stress resistance and biofilm formation in environmental <scp><i>Pseudomonas</i></scp> species

Terrettaz, Céline; Cabete, Bruno; Geiser, Johan; Valentini, Martina; González, Diego

doi:10.1111/1462-2920.16330

Cited by 3 publications

(1 citation statement)

References 61 publications

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“…Although kai homologs may be indicative of circadian function, their presence does not necessarily show that these taxa possess a circadian clock. There is evidence that Kai-like proteins may also be involved in other cellular processes such as stress response and biofilm formation [ 50 ], perhaps explaining their widespread presence in the genomes of diverse bacterial taxa.…”

Section: Circadian Clocks In Cyanobacteriamentioning

confidence: 99%

Microbial circadian clocks: host-microbe interplay in diel cycles

Wollmuth

Angert

2023

BMC Microbiol

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Background Circadian rhythms, observed across all domains of life, enable organisms to anticipate and prepare for diel changes in environmental conditions. In bacteria, a circadian clock mechanism has only been characterized in cyanobacteria to date. These clocks regulate cyclical patterns of gene expression and metabolism which contribute to the success of cyanobacteria in their natural environments. The potential impact of self-generated circadian rhythms in other bacterial and microbial populations has motivated extensive research to identify novel circadian clocks. Main text Daily oscillations in microbial community composition and function have been observed in ocean ecosystems and in symbioses. These oscillations are influenced by abiotic factors such as light and the availability of nutrients. In the ocean ecosystems and in some marine symbioses, oscillations are largely controlled by light-dark cycles. In gut systems, the influx of nutrients after host feeding drastically alters the composition and function of the gut microbiota. Conversely, the gut microbiota can influence the host circadian rhythm by a variety of mechanisms including through interacting with the host immune system. The intricate and complex relationship between the microbiota and their host makes it challenging to disentangle host behaviors from bacterial circadian rhythms and clock mechanisms that might govern the daily oscillations observed in these microbial populations. Conclusions While the ability to anticipate the cyclical behaviors of their host would likely be enhanced by a self-sustained circadian rhythm, more evidence and further studies are needed to confirm whether host-associated heterotrophic bacteria possess such systems. In addition, the mechanisms by which heterotrophic bacteria might respond to diel cycles in environmental conditions has yet to be uncovered.

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Section: Circadian Clocks In Cyanobacteriamentioning

confidence: 99%

Microbial circadian clocks: host-microbe interplay in diel cycles

Wollmuth

Angert

2023

BMC Microbiol

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Photomorphogenesis of Myxococcus macrosporus: new insights for light-regulation of cell development

Graniczkowska,

Bizhga,

Noda

et al. 2024

Photochem Photobiol Sci

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Myxobacteria are non-photosynthetic bacteria distinguished among prokaryotes by a multicellular stage in their life cycle known as fruiting bodies that are formed in response to nutrient deprivation and stimulated by light. Here, we report an entrained, rhythmic pattern of Myxococcus macrosporus fruiting bodies, forming consistently spaced concentric rings when grown in the dark. Light exposure disrupts this rhythmic phenotype, resulting in a sporadic arrangement and reduced fruiting-body count. M. macrosporus genome encodes a red-light photoreceptor, a bacteriophytochrome (BphP), previously shown to affect the fruiting-body formation in the related myxobacterium Stigmatella aurantiaca. Similarly, the formation of M. macrosporus fruiting bodies is also impacted by the exposure to BphP—specific wavelengths of light. RNA-Seq analysis of M. macrosporus revealed constitutive expression of the bphP gene. Phytochromes, as light-regulated enzymes, control many aspects of plant development including photomorphogenesis. They are intrinsically correlated to circadian clock proteins, impacting the overall light-mediated entrainment of the circadian clock. However, this functional relationship remains unexplored in non-photosynthetic prokaryotes. Genomic analysis unveiled the presence of multiple homologs of cyanobacterial core oscillatory gene, kaiC, in various myxobacteria, including M. macrosporus, S. aurantiaca and M. xanthus. RNA-Seq analysis verified the expression of all kaiC homologs in M. macrosporus and the closely related M. xanthus, which lacks bphP genes. Overall, this study unravels the rhythmic growth pattern during M. macrosporus development, governed by environmental factors such as light and nutrients. In addition, myxobacteria may have a time-measuring mechanism resembling the cyanobacterial circadian clock that links the photoreceptor (BphP) function to the observed rhythmic behavior. Graphical abstract

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Two circadian oscillators in one cyanobacterium

Koebler

Schmelling

Pawlowski

et al. 2021

Preprint

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The rotation of the Earth results in predictable environmental changes that pose challenges for organisms and force them to adapt. To address this daily rhythm, organisms from all kingdoms of life have evolved diverse timing mechanisms. In the cyanobacterium Synechococcus elongatus PCC 7942, the three proteins KaiA, KaiB, and KaiC constitute the central timing mechanism that drives circadian oscillations. In addition to the standard oscillator, named KaiAB1C1, Synechocystis sp. PCC 6803 harbors several, diverged clock homologs. The nonstandard KaiB3-KaiC3 system was suggested to impact the metabolic switch in response to darkness. Here, we demonstrate the direct interaction of KaiC3 with Sll0485, which is a potential new chimeric KaiA homolog that we named KaiA3. The existence of a functional link between these proteins is further supported by the co occurrence of genes encoding KaiA3 with the KaiB3-KaiC3-like gene products in 10 cyanobacterial and five other bacterial species. KaiA3 is annotated as a NarL-type response regulator due to its similarity to the response regulator receiver domains. However, its similarity to canonical NarL drastically decreases in the C-terminal domain, which resembles the circadian clock protein KaiA. In line with this, we detected the stimulation of KaiC3 phosphorylation by KaiA3 in vitro. Furthermore, we showed that deletion of the kaiA3 gene led to growth defects during mixotrophic growth conditions and, like a kaiC3-deficient mutant, viability was impaired during chemoheterotrophic growth in complete darkness. In summary, we suggest KaiA3 as a novel, nonstandard KaiA homolog within the cyanobacterial phylum, extending the KaiB3-KaiC3 system in Cyanobacteria and other prokaryotes.

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KaiC‐like proteins contribute to stress resistance and biofilm formation in environmental Pseudomonas species

Cited by 3 publications

References 61 publications

Microbial circadian clocks: host-microbe interplay in diel cycles

Microbial circadian clocks: host-microbe interplay in diel cycles

Photomorphogenesis of Myxococcus macrosporus: new insights for light-regulation of cell development

Two circadian oscillators in one cyanobacterium

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