Chloramphenicol causes fusion of separated nucleoids in Escherichia coli K-12 cells and filaments

Helvoort, J.M.L.M. van; Kool, Jolanda; Woldringh, Conrad L.

doi:10.1128/jb.178.14.4289-4293.1996

Cited by 65 publications

(60 citation statements)

References 17 publications

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“…At an optical density at 600 nm (OD 600 ) of 0.2, the protein overproduction was induced by the addition of 0.2% L-arabinose or repressed by the addition of 0.2% Dglucose. To monitor chromosome condensation, we adapted the cell fixation protocol developed by Nordstrom's group (5) because it yields fewer condensed nucleoids and nucleoid fusion events (1,56). In brief, 400 l of cells was mixed with 6.4 ml of ice-cold 74% ethanol--phosphate-buffered saline (PBS) mixture (70% final concentration of ethanol) and stored up to 1 week at 4°C.…”

Section: Methodsmentioning

confidence: 99%

Chromosome Condensation in the Absence of the Non-SMC Subunits of MukBEF

et al. 2006

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MukBEF is a bacterial SMC (structural maintenance of chromosome) complex required for chromosome partitioning in Escherichia coli. We report that overproduction of MukBEF results in marked chromosome condensation. This condensation is rapid and precedes the effects of overproduction on macromolecular synthesis. Condensed nucleoids are often mispositioned; however, cell viability is only mildly affected. The overproduction of MukB leads to a similar chromosome condensation, even in the absence of MukE and MukF. Thus, the non-SMC subunits of MukBEF play only an auxiliary role in chromosome condensation. MukBEF, however, was often a better condensin than MukB. Furthermore, the chromosome condensation by MukB did not rescue the temperature sensitivity of MukEF-deficient cells, nor did it suppress the high frequency of anucleate cell formation. We infer that the role of MukBEF in stabilizing chromatin architecture is more versatile than its role in controlling chromosome size. We further propose that MukBEF could be directly involved in chromosome segregation.

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Section: Methodsmentioning

confidence: 99%

Chromosome Condensation in the Absence of the Non-SMC Subunits of MukBEF

et al. 2006

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“…In some cases, we used chloramphenicol and rifampin to alter the relative size of nucleoids in the cells. Chloramphenicol inhibits translation, which leads to nucleoid condensation (25,27). Rifampin inhibits transcription, which results in nucleoid expansion (26,27).…”

Section: Chemicalsmentioning

confidence: 99%

“…One such stress-inducing antibiotic is chloramphenicol, which halts translation elongation by blocking access of charged tRNA to the ribosomal A site (28), leading to nucleoid compaction (25). Meanwhile, another antibiotic, rifampin, blocks transcription initiation by binding to RNA polymerases (29), leading to nucleoid expansion (27).…”

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Robustness of the Process of Nucleoid Exclusion of Protein Aggregates in Escherichia coli

et al. 2016

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Escherichia coli segregates protein aggregates to the poles by nucleoid exclusion. Combined with cell divisions, this generates heterogeneous aggregate distributions in subsequent cell generations. We studied the robustness of this process with differing medium richness and antibiotics stress, which affect nucleoid size, using multimodal, time-lapse microscopy of live cells expressing both a fluorescently tagged chaperone (IbpA), which identifies in vivo the location of aggregates, and HupA-mCherry, a fluorescent variant of a nucleoid-associated protein. We find that the relative sizes of the nucleoid's major and minor axes change widely, in a positively correlated fashion, with medium richness and antibiotic stress. The aggregate's distribution along the major cell axis also changes between conditions and in agreement with the nucleoid exclusion phenomenon. Consequently, the fraction of aggregates at the midcell region prior to cell division differs between conditions, which will affect the degree of asymmetries in the partitioning of aggregates between cells of future generations. Finally, from the location of the peak of anisotropy in the aggregate displacement distribution, the nucleoid relative size, and the spatiotemporal aggregate distribution, we find that the exclusion of detectable aggregates from midcell is most pronounced in cells with mid-sized nucleoids, which are most common under optimal conditions. We conclude that the aggregate management mechanisms of E. coli are significantly robust but are not immune to stresses due to the tangible effect that these have on nucleoid size. IMPORTANCEEscherichia coli segregates protein aggregates to the poles by nucleoid exclusion. From live single-cell microscopy studies of the robustness of this process to various stresses known to affect nucleoid size, we find that nucleoid size and aggregate preferential locations change concordantly between conditions. Also, the degree of influence of the nucleoid on aggregate positioning differs between conditions, causing aggregate numbers at midcell to differ in cell division events, which will affect the degree of asymmetries in the partitioning of aggregates between cells of future generations. Finally, we find that aggregate segregation to the cell poles is most pronounced in cells with mid-sized nucleoids. We conclude that the energy-free process of the midcell exclusion of aggregates partially loses effectiveness under stressful conditions.

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“…Treatment of E. coli filaments with protein synthesis inhibitors causes arrest of ongoing chromosome segregation and nucleoids appear to coalesce (van Helvoort et al, 1996;Van Helvoort et al, 1998). Upon relief of the inhibition, nucleoids rapidly segregate.…”

Section: Introductionmentioning

confidence: 99%

Chromosome segregation control by Escherichia coli ObgE GTPase

Foti

Persky²,

Ferullo

et al. 2007

Molecular Microbiology

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SummaryEscherichia coli cells depleted of the conserved GTPase, ObgE, show early chromosome-partitioning defects and accumulate replicated chromosomes in which the terminus regions are colocalized. Cells lacking ObgE continue to initiate replication, with a normal ratio of the origin to terminus. Localization of the SeqA DNA binding protein, normally seen as punctate foci, however, was disturbed. Depletion of ObgE also results in cell filamentation, with polyploid DNA content. Depletion of ObgE did not cause lethality, and cells recovered fully after expression of ObgE was restored. We propose a model in which ObgE is required to license chromosome segregation and subsequent cell cycle events.

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Chloramphenicol causes fusion of separated nucleoids in Escherichia coli K-12 cells and filaments

Cited by 65 publications

References 17 publications

Chromosome Condensation in the Absence of the Non-SMC Subunits of MukBEF

Chromosome Condensation in the Absence of the Non-SMC Subunits of MukBEF

Robustness of the Process of Nucleoid Exclusion of Protein Aggregates in Escherichia coli

Chromosome segregation control by Escherichia coli ObgE GTPase

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