KaiC protein is the pivotal component of the circadian clock in cyanobacteria. While KaiC family proteins are well-conserved throughout divergent phylogenetic lineages, studies of the physiological roles of KaiC proteins from other microorganisms have been limited. We examined the role of the KaiC proteins, KaiC1 and KaiC2, in the methanol-utilizing bacterium Methylobacterium extorquens AM1. Wild-type M. extorquens AM1 cells exhibited temperature-dependent UV resistance (TDR) under permissive growth temperatures (24 °C -32 °C). Both the phosphorylation of KaiC2 and the intracellular levels of KaiC1 were temperature-dependent, and the TDR phenotype was positively regulated by KaiC1 and negatively regulated by KaiC2. Taken together with biochemical and functional analogies to the KaiC protein of cyanobacteria, our present results suggest that KaiC family proteins function to integrate environmental cues, that is, temperature and UV light, and output appropriate cellular responses to allow cells to adapt to changing environmental conditions.© 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.
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http://dx.doi.org/10.1111/1758-2229.12662 | DOI Listing |
Sci Rep
December 2024
Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
A circadian clock is reconstituted in vitro by incubating three proteins, KaiA, KaiB, and KaiC from the non-nitrogen-fixing cyanobacterium Synechococcus elongatus PCC 7942 in the presence of ATP. Leptolyngbya boryana is a filamentous cyanobacterium that grows diazotrophically under microoxic conditions. Among the aforementioned proteins, KaiC is the main clock oscillator belonging to the RecA ATPase superfamily.
View Article and Find Full Text PDFNat Commun
September 2024
Institute of Biology III, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany.
The circadian clock of cyanobacteria, which predicts daily environmental changes, typically includes a standard oscillator consisting of proteins KaiA, KaiB, and KaiC. However, several cyanobacteria have diverse Kai protein homologs of unclear function. In particular, Synechocystis sp.
View Article and Find Full Text PDFAnimals (Basel)
September 2023
Divison of Animal Science, Faculty of Agriculture, University of Zagreb, Svetošimunska cesta 25, 10000 Zagreb, Croatia.
Environ Microbiol
April 2023
Laboratoire de Microbiologie, Institut de Biologie, Université de Neuchâtel, Neuchâtel, Switzerland.
KaiC is the central cog of the circadian clock in Cyanobacteria. Close homologues of this protein are widespread among nonphotosynthetic bacteria, but the function, interaction network, and mechanism of action of these proteins are still largely unknown. Here, we focus on KaiC homologues found in environmental Pseudomonas species.
View Article and Find Full Text PDFNat Struct Mol Biol
August 2022
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, USA.
The AAA family member KaiC is the central pacemaker for circadian rhythms in the cyanobacterium Synechococcus elongatus. Composed of two hexameric rings of adenosine triphosphatase (ATPase) domains with tightly coupled activities, KaiC undergoes a cycle of autophosphorylation and autodephosphorylation on its C-terminal (CII) domain that restricts binding of clock proteins on its N-terminal (CI) domain to the evening. Here, we use cryogenic-electron microscopy to investigate how daytime and nighttime states of CII regulate KaiB binding on CI.
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