The <i><scp>L</scp>egionella pneumophila kai</i> operon is implicated in stress response and confers fitness in competitive environments

Loza-Correa, Maria; Sahr, Tobias; Rolando, Monica; Daniels, Craig; Petit, P.; Skarina, T.; Gómez-Valero, Laura; Dervins-Ravault, Delphine; Honoré, Nadine; Savchenko, Aleksey; Buchrieser, Carmen

doi:10.1111/1462-2920.12223

Cited by 27 publications

(29 citation statements)

References 92 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

“…In L. pneumophila, kaiB and kaiC are organized in an operon that is under the control of the stress sigma factor RpoS and that has a growth-phase-dependent expression profile (97). While L. pneumophila KaiC is capable of autophosphorylation, no interaction between KaiB and KaiC was detected using two-hybrid approaches (97). Mutation of the kaiC operon resulted in strains with enhanced sensitivity to oxidative and salt stress, suggesting that kaiBC may play a role in cellular stress responses (97).…”

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

“…While L. pneumophila KaiC is capable of autophosphorylation, no interaction between KaiB and KaiC was detected using two-hybrid approaches (97). Mutation of the kaiC operon resulted in strains with enhanced sensitivity to oxidative and salt stress, suggesting that kaiBC may play a role in cellular stress responses (97). Interestingly, kaiC2 from Synechocystis sp.…”

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

“…Although rigorous investigations into roles for the Legionella kaiB and kaiC homologs in circadian timekeeping have not been undertaken, the results of these studies suggest that kaiBC homologs found outside cyanobacteria may participate in other biological processes. Interestingly, the crystal structure of L. pneumophila KaiB revealed that it assumes the fold-switched form (97). Remarkably, the amino acid substitutions that were introduced to stabilize the fold-switched (KaiC-interacting [41]) state in S. elongatus are the same residues that are found naturally in those positions in L. pneumophila as well as in other organisms.…”

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

See 3 more Smart Citations

Circadian Rhythms in Cyanobacteria

Cohen

Golden

2015

Microbiol Mol Biol Rev

230

220

View full text Add to dashboard Cite

SUMMARYLife on earth is subject to daily and predictable fluctuations in light intensity, temperature, and humidity created by rotation of the earth. Circadian rhythms, generated by a circadian clock, control temporal programs of cellular physiology to facilitate adaptation to daily environmental changes. Circadian rhythms are nearly ubiquitous and are found in both prokaryotic and eukaryotic organisms. Here we introduce the molecular mechanism of the circadian clock in the model cyanobacteriumSynechococcus elongatusPCC 7942. We review the current understanding of the cyanobacterial clock, emphasizing recent work that has generated a more comprehensive understanding of how the circadian oscillator becomes synchronized with the external environment and how information from the oscillator is transmitted to generate rhythms of biological activity. These results have changed how we think about the clock, shifting away from a linear model to one in which the clock is viewed as an interactive network of multifunctional components that are integrated into the context of the cell in order to pace and reset the oscillator. We conclude with a discussion of how this basic timekeeping mechanism differs in other cyanobacterial species and how information gleaned from work in cyanobacteria can be translated to understanding rhythmic phenomena in other prokaryotic systems.

show abstract

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

Section: Kai Proteins Outside Cyanobacteriamentioning

confidence: 99%

See 2 more Smart Citations

Circadian Rhythms in Cyanobacteria

Cohen

Golden

2015

Microbiol Mol Biol Rev

230

220

View full text Add to dashboard Cite

show abstract

“…Crystal structures are available for KaiB1 homologs and KaiB2 from Legionella pneumophila [133][134][135][136][137][138]. Free KaiB1 crystallizes in a unique fold, but can adopt a fold switched state, which is a prerequisite for KaiC binding and is similar to the thioredoxin like fold observed in KaiB2 crystals [138,139].…”

Section: Conserved Motifs and Activities In The Cyanobacterial Kaic Smentioning

confidence: 99%

Minimal Tool Set for a Prokaryotic Circadian Clock

Schmelling

Wiegard

Lehmann

et al. 2016

Preprint

View full text Add to dashboard Cite

Background: Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating. However, interaction and function of non-cyanobacterial Kai-proteins as well as homologous input and output components remain mainly unclear. Results: Using a universal BLAST analyses, we identified putative KaiC-based timing systems in organisms outside as well as variations within Cyanobacteria. A systematic analyses of publicly available microarray data elucidated interesting variations in circadian gene expression between different cyanobacterial strains, which might be correlated to the diversity of genome encoded clock components. Based on statistical analyses of co-occurrences of the clock components homologous to Synechococcus elongatus PCC 7942, we propose putative networks of reduced and fully functional clock systems. Further, we studied KaiC sequence conservation to determine functionally important regions of diverged KaiC homologs. Biochemical characterization of exemplary cyanobacterial KaiC proteins as well as homologs from two thermophilic Archaea demonstrated that kinase activity is always present. However, a KaiA-mediated phosphorylation is only detectable in KaiC1 orthologs. Conclusion: Our analysis of 11,264 genomes clearly demonstrates that components of the Synechococcus elongatus PCC 7942 circadian clock are present in Bacteria and Archaea. However, all components are less abundant in other organisms than Cyanobacteria and KaiA, Pex, LdpA, and CdpA are only present in the latter. Thus, only reduced KaiBC-based or even simpler, solely KaiC-based timing systems might exist outside of the cyanobacterial phylum, which might be capable of driving diurnal oscillations.

show abstract

A high‐throughput predictive method for sequence‐similar fold switchers

2021

View full text Add to dashboard Cite

Although most experimentally characterized proteins with similar sequences assume the same folds and perform similar functions, an increasing number of exceptions is emerging. One class of exceptions comprises sequence-similar fold switchers, whose secondary structures shift from α-helix <-> β-sheet through a small number of mutations, a sequence insertion, or a deletion. Predictive methods for identifying sequence-similar fold switchers are desirable because some are associated with disease and/or can perform different functions in cells. Here, we use homology-based secondary structure predictions to identify sequence-similar fold switchers from their amino acid sequences alone. To do this, we predicted the secondary structures of sequence-similar fold switchers using three different homology-based secondary structure predictors: PSIPRED, JPred4, and SPIDER3. We found that α-helix <-> β-strand prediction discrepancies from JPred4 discriminated between the different conformations of sequencesimilar fold switchers with high statistical significance (P < 1.8*10 −19 ). Thus, we used these discrepancies as a classifier and found that they can often robustly discriminate between sequence-similar fold switchers and sequence-similar proteins that maintain the same folds (Matthews Correlation Coefficient of 0.82). We found that JPred4 is a more robust predictor of sequence-similar fold switchers because of (a) the curated sequence database it uses to produce multiple sequence alignments and (b) its use of sequence profiles based on Hidden Markov Models. Our results indicate that inconsistencies between JPred4 secondary structure predictions can be used to identify some sequence-similar fold switchers from their sequences alone. Thus, the negative information from inconsistent secondary structure predictions can potentially be leveraged to identify sequence-similar fold switchers from the broad base of genomic sequences.

show abstract

The Legionella pneumophila kai operon is implicated in stress response and confers fitness in competitive environments

Cited by 27 publications

References 92 publications

Circadian Rhythms in Cyanobacteria

Circadian Rhythms in Cyanobacteria

Minimal Tool Set for a Prokaryotic Circadian Clock

A high‐throughput predictive method for sequence‐similar fold switchers

Contact Info

Product

Resources

About