scholarly journals Activation of a signaling pathway by the physical translocation of a chromosome

2021 ◽  
Author(s):  
Mathilde Guzzo ◽  
Allen G. Sanderlin ◽  
Lennice K. Castro ◽  
Michael T. Laub
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Signaling Pathway ◽  
Chromosome Segregation ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Dna Replication Initiation ◽  
Cellular Processes ◽  
Initiation Of Dna Replication

AbstractIn every organism, the cell cycle requires the execution of multiple cellular processes in a strictly defined order. However, the mechanisms used to ensure such order remain poorly understood, particularly in bacteria. Here, we show that the activation of the essential CtrA signaling pathway that triggers cell division in Caulobacter crescentus is intrinsically coupled to the successful initiation of DNA replication via the physical translocation of a newly-replicated chromosome, powered by the ParABS system. We demonstrate that ParA accumulation at the new cell pole during chromosome segregation recruits ChpT, an intermediate component of the CtrA signaling pathway. ChpT is normally restricted from accessing the selective PopZ polar microdomain until the new chromosome and ParA arrive. Consequently, any disruption to DNA replication initiation prevents the recruitment of ChpT and, in turn, cell division. Collectively, our findings reveal how major cell-cycle events are coordinated in Caulobacter and, importantly, how the physical translocation of a chromosome triggers an essential signaling pathway.

scholarly journals Polar Remodeling and Histidine Kinase Activation, Which Is Essential for Caulobacter Cell Cycle Progression, Are Dependent on DNA Replication Initiation

2010 ◽  
Vol 192 (15) ◽  
pp. 3893-3902 ◽  
Author(s):  
Antonio A. Iniesta ◽  
Nathan J. Hillson ◽  
Lucy Shapiro
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Histidine Kinase ◽  
Cell Cycle Progression ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Cycle Progression ◽  
Dna Replication Initiation ◽  
Flagellar Biosynthesis ◽  
Initiation Of Dna Replication

ABSTRACT Caulobacter crescentus initiates a single round of DNA replication during each cell cycle. Following the initiation of DNA replication, the essential CckA histidine kinase is activated by phosphorylation, which (via the ChpT phosphotransferase) enables the phosphorylation and activation of the CtrA global regulator. CtrA∼P then blocks the reinitiation of replication while regulating the transcription of a large number of cell cycle-controlled genes. It has been shown that DNA replication serves as a checkpoint for flagellar biosynthesis and cell division and that this checkpoint is mediated by the availability of active CtrA. Because CckA∼P promotes the activation of CtrA, we addressed the question of what controls the temporal activation of CckA. We found that the initiation of DNA replication is a prerequisite for remodeling the new cell pole, which includes the localization of the DivL protein kinase to that pole and, consequently, the localization, autophosphorylation, and activation of CckA at that pole. Thus, CckA activation is dependent on polar remodeling and a DNA replication initiation checkpoint that is tightly integrated with the polar phospho-signaling cascade governing cell cycle progression.

A Novel Fluorescence-Based Screen for Inhibitors of the Initiation of DNA Replication in Bacteria

2019 ◽  
Vol 16 (3) ◽  
pp. 272-277 ◽  
Author(s):  
Rasmus N. Klitgaard ◽  
Anders Løbner-Olesen
Keyword(s):  
Dna Replication ◽  
High Throughput ◽  
Cyclic Peptide ◽  
Replication Initiation ◽  
False Positive Result ◽  
Over Expression ◽  
Initiator Protein ◽  
Dna Replication Initiation ◽  
Cellular Processes ◽  
Initiation Of Dna Replication

Background:One of many strategies to overcome antibiotic resistance is the discovery of compounds targeting cellular processes, which have not yet been exploited.Materials and Methods:Using various genetic tools, we constructed a novel high throughput, cellbased, fluorescence screen for inhibitors of chromosome replication initiation in bacteria.Results:The screen was validated by expression of an intra-cellular cyclic peptide interfering with the initiator protein DnaA and by over-expression of the negative initiation regulator SeqA. We also demonstrated that neither tetracycline nor ciprofloxacin triggers a false positive result. Finally, 400 extracts isolated mainly from filamentous actinomycetes were subjected to the screen.Conclusion:We concluded that the presented screen is applicable for identifying putative inhibitors of DNA replication initiation in a high throughput setup.

scholarly journals Control of DNA Replication Initiation by Ubiquitin

Cells ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 146 ◽  
Author(s):  
Esperanza Hernández-Carralero ◽  
Elisa Cabrera ◽  
Ignacio Alonso-de Vega ◽  
Santiago Hernández-Pérez ◽  
Veronique Smits ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Replication Initiation ◽  
Post Translational Modifications ◽  
Precise Control ◽  
Dna Replication Initiation ◽  
Fundamental Part ◽  
Initiation Of Dna Replication ◽  
The Right ◽  
Hydrolysis Of

Eukaryotic cells divide by accomplishing a program of events in which the replication of the genome is a fundamental part. To ensure all cells have an accurate copy of the genome, DNA replication occurs only once per cell cycle and is controlled by numerous pathways. A key step in this process is the initiation of DNA replication in which certain regions of DNA are marked as competent to replicate. Moreover, initiation of DNA replication needs to be coordinated with other cell cycle processes. At the molecular level, initiation of DNA replication relies, among other mechanisms, upon post-translational modifications, including the conjugation and hydrolysis of ubiquitin. An example is the precise control of the levels of the DNA replication initiation protein Cdt1 and its inhibitor Geminin by ubiquitin-mediated proteasomal degradation. This control ensures that DNA replication occurs with the right timing during the cell cycle, thereby avoiding re-replication events. Here, we review the events that involve ubiquitin signalling during DNA replication initiation, and how they are linked to human disease.

scholarly journals Coordination between Chromosome Replication, Segregation, and Cell Division in Caulobacter crescentus

2006 ◽  
Vol 188 (6) ◽  
pp. 2244-2253 ◽  
Author(s):  
Rasmus B. Jensen
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Cytoplasmic Membrane ◽  
Caulobacter Crescentus ◽  
Chromosome Replication ◽  
Short Delay ◽  
Swarmer Cell ◽  
Initiation Of Dna Replication ◽  
Cell Transition

ABSTRACT Progression through the Caulobacter crescentus cell cycle is coupled to a cellular differentiation program. The swarmer cell is replicationally quiescent, and DNA replication initiates at the swarmer-to-stalked cell transition. There is a very short delay between initiation of DNA replication and movement of one of the newly replicated origins to the opposite pole of the cell, indicating the absence of cohesion between the newly replicated origin-proximal parts of the Caulobacter chromosome. The terminus region of the chromosome becomes located at the invaginating septum in predivisional cells, and the completely replicated terminus regions stay associated with each other after chromosome replication is completed, disassociating very late in the cell cycle shortly before the final cell division event. Invagination of the cytoplasmic membrane occurs earlier than separation of the replicated terminus regions and formation of separate nucleoids, which results in trapping of a chromosome on either side of the cell division septum, indicating that there is not a nucleoid exclusion phenotype.

Efficiency and equity in origin licensing to ensure complete DNA replication

2021 ◽  
Author(s):  
Liu Mei ◽  
Jeanette Gowen Cook
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Genome Stability ◽  
S Phase ◽  
Replication Initiation ◽  
G1 Phase ◽  
Dna Replication Initiation ◽  
Origin Licensing ◽  
Dna Replication Origins

The cell division cycle must be strictly regulated during both development and adult maintenance, and efficient and well-controlled DNA replication is a key event in the cell cycle. DNA replication origins are prepared in G1 phase of the cell cycle in a process known as origin licensing which is essential for DNA replication initiation in the subsequent S phase. Appropriate origin licensing includes: (1) Licensing enough origins at adequate origin licensing speed to complete licensing before G1 phase ends; (2) Licensing origins such that they are well-distributed on all chromosomes. Both aspects of licensing are critical for replication efficiency and accuracy. In this minireview, we will discuss recent advances in defining how origin licensing speed and distribution are critical to ensure DNA replication completion and genome stability.

scholarly journals SpoT Regulates DnaA Stability and Initiation of DNA Replication in Carbon-Starved Caulobacter crescentus

2008 ◽  
Vol 190 (20) ◽  
pp. 6867-6880 ◽  
Author(s):  
Joseph A. Lesley ◽  
Lucy Shapiro
Keyword(s):  
Dna Replication ◽  
Cell Cycle Progression ◽  
Caulobacter Crescentus ◽  
Morphological Differentiation ◽  
State Level ◽  
Carbon Starvation ◽  
Replication Initiation ◽  
Swarmer Cell ◽  
Dna Replication Initiation ◽  
Initiation Of Dna Replication

ABSTRACT Cell cycle progression and polar differentiation are temporally coordinated in Caulobacter crescentus. This oligotrophic bacterium divides asymmetrically to produce a motile swarmer cell that represses DNA replication and a sessile stalked cell that replicates its DNA. The initiation of DNA replication coincides with the proteolysis of the CtrA replication inhibitor and the accumulation of DnaA, the replication initiator, upon differentiation of the swarmer cell into a stalked cell. We analyzed the adaptive response of C. crescentus swarmer cells to carbon starvation and found that there was a block in both the swarmer-to-stalked cell polar differentiation program and the initiation of DNA replication. SpoT is a bifunctional synthase/hydrolase that controls the steady-state level of the stress-signaling nucleotide (p)ppGpp, and carbon starvation caused a SpoT-dependent increase in (p)ppGpp concentration. Carbon starvation activates DnaA proteolysis (B. Gorbatyuk and G. T. Marczynski, Mol. Microbiol. 55:1233-1245, 2005). We observed that SpoT is required for this phenomenon in swarmer cells, and in the absence of SpoT, carbon-starved swarmer cells inappropriately initiated DNA replication. Since SpoT controls (p)ppGpp abundance, we propose that this nucleotide relays carbon starvation signals to the cellular factors responsible for activating DnaA proteolysis, thereby inhibiting the initiation of DNA replication. SpoT, however, was not required for the carbon starvation block of the swarmer-to-stalked cell polar differentiation program. Thus, swarmer cells utilize at least two independent signaling pathways to relay carbon starvation signals: a SpoT-dependent pathway mediating the inhibition of DNA replication initiation, and a SpoT-independent pathway(s) that blocks morphological differentiation.

scholarly journals tmRNA Is Required for Correct Timing of DNA Replication in Caulobacter crescentus

2003 ◽  
Vol 185 (2) ◽  
pp. 573-580 ◽  
Author(s):  
Kenneth C. Keiler ◽  
Lucy Shapiro
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Small Rna ◽  
Caulobacter Crescentus ◽  
Response Regulator ◽  
Replication Initiation ◽  
Gene Encoding ◽  
Initiation Of Replication ◽  
Initiation Of Dna Replication ◽  
Dependent Pathway

ABSTRACT SsrA, or tmRNA, is a small RNA that interacts with selected translating ribosomes to target the nascent polypeptides for degradation. Here we report that SsrA activity is required for normal timing of the G1-to-S transition in Caulobacter crescentus. A deletion of the ssrA gene, or of the gene encoding SmpB, a protein required for SsrA activity, results in a specific delay in the cell cycle during the G1-to-S transition. The ssrA deletion phenotype is not due to accumulation of stalled ribosomes, because the deletion is not complemented by a mutated version of SsrA that releases ribosomes but does not target proteins for degradation. Degradation of the CtrA response regulator normally coincides with initiation of DNA replication, but in strains lacking SsrA activity there is a 40-min delay between the degradation of CtrA and replication initiation. This uncoupling of initiation of replication from CtrA degradation indicates that there is an SsrA-dependent pathway required for correct timing of DNA replication.

scholarly journals Correct Timing of dnaA Transcription and Initiation of DNA Replication Requires trans Translation

2009 ◽  
Vol 191 (13) ◽  
pp. 4268-4275 ◽  
Author(s):  
Lin Cheng ◽  
Kenneth C. Keiler
Keyword(s):  
Gene Expression ◽  
Dna Replication ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Proximal Promoter ◽  
Dna Replication Initiation ◽  
Proliferation And Differentiation ◽  
Initiation Of Dna Replication ◽  
Protein Tagging

ABSTRACT The trans translation pathway for protein tagging and ribosome release has been found in all bacteria and is required for proliferation and differentiation in many systems. Caulobacter crescentus mutants that lack the trans translation pathway have a defect in the cell cycle and do not initiate DNA replication at the correct time. To determine the molecular basis for this phenotype, effects on events known to be important for initiation of DNA replication were investigated. In the absence of trans translation, transcription from the dnaA promoter and an origin-proximal promoter involved in replication initiation is delayed. Characterization of the dnaA promoter revealed two cis-acting elements that have dramatic effects on dnaA gene expression. A 5′ leader sequence in dnaA mRNA represses gene expression by >15-fold but does not affect the timing of dnaA expression. The second cis-acting element, a sequence upstream of the −35 region, affects both the amount of dnaA transcription and the timing of transcription in response to trans translation. Mutations in this promoter element eliminate the transcription delay and partially suppress the DNA replication phenotype in mutants lacking trans translation activity. These results suggest that the trans translation capacity of the cell is sensed through the dnaA promoter to control the timing of DNA replication initiation.

scholarly journals DNA Content and Nucleoid Distribution in Methanothermobacter thermautotrophicus

2005 ◽  
Vol 187 (5) ◽  
pp. 1856-1858 ◽  
Author(s):  
Alan I. Majerník ◽  
Magnus Lundgren ◽  
Paul McDermott ◽  
Rolf Bernander ◽  
James P. J. Chong
Keyword(s):  
Flow Cytometry ◽  
Dna Replication ◽  
Chromosome Segregation ◽  
Dna Content ◽  
Replication Initiation ◽  
Epifluorescence Microscopy ◽  
Single Chromosome ◽  
Dna Replication Initiation ◽  
Methanothermobacter Thermautotrophicus ◽  
Multiple Cells

ABSTRACT Flow cytometry and epifluorescence microscopy results for the euryarchaeon Methanothermobacter thermautotrophicus were consistent with filaments containing multiple cells. Filaments of one to four cells contained two to eight nucleoids. Single chromosome-containing cells were not observed. Filaments containing multiple genome copies displayed synchronous DNA replication initiation. Chromosome segregation occurred during replication or rapidly after replication termination.

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