The effect of trans-[Rh(4-ethylpyridine)4Cl2]Cl∙2H2O on nucleic acid and protein syntheses in Escherichia coli

1980 ◽  
Vol 26 (5) ◽  
pp. 636-639
Author(s):  
S. L. Seeman ◽  
T. R. Jack
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Cell Division ◽  
Nucleic Acid ◽  
Normal Cell ◽  
Rhodium Complex ◽  
Platinum Compounds ◽  
Transition Metal Compound ◽  
Macromolecular Synthesis ◽  
Antitumour Agents

The effect of the transition metal compound trans-[Rh(4-ethylpyridine)4Cl2]Cl∙2H2O on the syntheses of DNA, RNA, and protein has been investigated for an auxotrophic bacterial strain, Escherichia coli JS-1, incapable of thymidine, uridine, and histidine syntheses. At low concentration (7.4 × 10−6 M), this rhodium complex interferes with normal cell division and induces the formation of filaments comparable to those observed in the presence of the cis-(NH3)2PtClx antitumour agents. Once the suppressed growth rate of the filamenting cells has been taken into account, the rhodium compound is found not to alter macromolecular synthesis. Again this is consistent with similar observations made for the platinum compounds.

scholarly journals Replication-Related Control Over Cell Division in Escherichia Coli is Growth-Rate Dependent

2021 ◽  
Author(s):  
Sriram Tiruvadi-Krishnan ◽  
Jaana Männik ◽  
Prathitha Kar ◽  
Jie Lin ◽  
Ariel Amir ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Cell Division ◽  
Rate Dependent

scholarly journals Flow Cytometric Investigation of Filamentation, Membrane Patency, and Membrane Potential in Escherichia coli following Ciprofloxacin Exposure

2000 ◽  
Vol 44 (3) ◽  
pp. 682-687 ◽  
Author(s):  
H. J. Wickens ◽  
R. J. Pinney ◽  
D. J. Mason ◽  
V. A. Gant
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Cell Division ◽  
Membrane Potential ◽  
Nucleic Acid ◽  
Nutrient Broth ◽  
Nucleic Acid Binding ◽  
Dye Uptake ◽  
Flow Cytometric ◽  
Drug Removal

ABSTRACT Ninety-eight percent of the cells in a population ofEscherichia coli in log-phase growth lost colony-forming ability after being exposed for 3 h to the quinolone antibiotic ciprofloxacin at four times the MIC in nutrient broth, a concentration easily reached in vivo. Flow cytometric analysis, however, demonstrated that only 68% of this bacterial population had lost membrane potential, as judged by the membrane potential-sensitive dye bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)], and only 30% could no longer exclude the nucleic acid-binding dye propidium iodide (PI), reflecting lost membrane integrity, efflux mechanisms, or both. Subsequent removal of ciprofloxacin and resuspension in nutrient broth resulted in renewed cell division after 2 h, with a calculated postantibiotic effect (PAE) time of 57 min. The proportion of DiBAC- and PI-fluorescent cells in this recovering population remained stable for more than 4 h after antibiotic removal. Eighty percent of cells present at drug removal were filamentous. Their number subsequently decreased with time, and the increase in particle count seen at the end of the PAE resulted from the division of short cells. Exposure to ciprofloxacin in the presence of the protein synthesis inhibitor chloramphenicol increased colony-forming ability to 60% of starting population numbers. In contrast to ciprofloxacin alone, this antibiotic combination resulted in insignificant filamentation and no dye uptake. Subsequent drug removal and resuspension in nutrient broth resulted in the appearance of filaments within 1 h, with 69% of the population forming filaments at 3 h. Dye uptake was also seen, with 20% of the population fluorescing with either dye after 4 h. We were unable to relate dye uptake to the viable count. Cell division resumed 240 min after removal of both drugs, yielding a PAE calculated at 186 min. Inhibition of protein synthesis with chloramphenicol prevented ciprofloxacin-induced changes in bacterial morphology, cell membrane potential, and ability to exclude nucleic acid-binding dye. These changes persisted beyond the end of the classically defined PAE and were not a definite indicator of cell death as defined by loss of colony formation, which related at least in part to filamentation.

scholarly journals Bex, the Bacillus subtilis Homolog of the Essential Escherichia coli GTPase Era, Is Required for Normal Cell Division and Spore Formation

2002 ◽  
Vol 184 (22) ◽  
pp. 6389-6394 ◽  
Author(s):  
Natalie Minkovsky ◽  
Arash Zarimani ◽  
Vasant K. Chary ◽  
Brian H. Johnstone ◽  
Bradford S. Powell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Cell Division ◽  
Normal Cell ◽  
Spore Formation ◽  
E Coli ◽  
Mutant Cells

ABSTRACT The Bacillus subtilis bex gene complemented the defect in an Escherichia coli era mutant. The Bex protein showed 39% identity and 67% similarity to the E. coli Era GTPase. In contrast to era, bex was not essential in all strains. bex mutant cells were elongated and filled with diffuse nucleoid material. They grew slowly and exhibited severely impaired spore formation.

scholarly journals Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication

2007 ◽  
Vol 189 (23) ◽  
pp. 8660-8666 ◽  
Author(s):  
Henrik J. Nielsen ◽  
Brenda Youngren ◽  
Flemming G. Hansen ◽  
Stuart Austin
Keyword(s):  
Escherichia Coli ◽  
Cell Cycle ◽  
Growth Rate ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Replication Forks ◽  
Daughter Cells ◽  
Initiation Of Replication ◽  
Replication Terminus ◽  
Multiple Replication

ABSTRACT Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks.

scholarly journals Inefficient Tat-Dependent Export of Periplasmic Amidases in an Escherichia coli Strain with Mutations in Two DedA Family Genes

2009 ◽  
Vol 192 (3) ◽  
pp. 807-818 ◽  
Author(s):  
Rakesh Sikdar ◽  
William T. Doerrler
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Temperature Sensitivity ◽  
Normal Cell ◽  
Secretory Pathway ◽  
Elevated Temperatures ◽  
Fluorescent Protein ◽  
Proper Function ◽  
Membrane Composition ◽  
Membrane Phospholipids

ABSTRACT The DedA family genes are found in most bacterial genomes. Two of these proteins are Escherichia coli YqjA and YghB, predicted inner membrane proteins of unknown function sharing 61% amino acid identity. The E. coli single deletion mutants are largely without phenotype, but the double mutant (BC202; ΔyqjA::Tetr ΔyghB::Kanr) is characterized by incomplete cell division, temperature sensitivity, and altered phospholipid levels (K. Thompkins et al., J. Bacteriol. 190:4489-4500, 2008). In this report, we have better characterized the cell division chaining defect of BC202. Fluorescence recovery after photobleaching indicates that 58% of the cells in chains are compartmentalized by at least a cytoplasmic membrane. Green fluorescent protein fusions to the cell division proteins FtsZ, ZipA, FtsI, FtsL, and FtsQ are correctly localized to new septation sites in BC202. Periplasmic amidases AmiC and AmiA, secreted by the twin arginine transport (Tat) pathway, are localized to the cytoplasm in BC202. Overexpression of AmiA, AmiC, or AmiB, a periplasmic amidase secreted via the general secretory pathway, restores normal cell division but does not suppress the temperature sensitivity of BC202, indicating that YghB and YqjA may play additional roles in cellular physiology. Strikingly, overexpression of the Tat export machinery (TatABC) results in normal cell division and growth at elevated temperatures. These data collectively suggest that the twin arginine pathway functions inefficiently in BC202, likely due to the altered levels of membrane phospholipids in this mutant. These results underscore the importance of membrane composition in the proper function of the Tat protein export pathway.

The cytological effects of myxin on Escherichia coli

1969 ◽  
Vol 15 (7) ◽  
pp. 707-711 ◽  
Author(s):  
I. L. Stevenson
Keyword(s):  
Escherichia Coli ◽  
Plasma Membrane ◽  
Cell Division ◽  
Cell Surface ◽  
Microscopic Examination ◽  
Cell Elongation ◽  
Nuclear Bodies ◽  
Abnormal Development ◽  
Macromolecular Synthesis ◽  
Apparent Effect

When actively growing cells of Escherichia coli 15T− were treated with the new antibiotic myxin, the effects produced by the antibiotic varied, depending on the concentration. With a concentration of 1 μg/ml, the action was bacteriostatic for the first 60 min exposure. Cell division was inhibited but there was no apparent effect on macromolecular synthesis as evidenced by the formation of filamentous cells. At higher concentrations (3 and 5 μg/ml), myxin was bactericidal although some cell elongation occurred at the 3 μg/ml level. Microscopic examination of cells treated with 3 and 5 μg/ml for 30–45 min indicated the presence of vacuolated areas which thin section studies revealed as intracellular ramifications of the plasma membrane. Protoplasts of cells grown in the presence of 5 μg/ml myxin were enlarged or rapidly lysed even after as little as 15 min exposure. Myxin has no effect on the cell surface of control protoplasts. No abnormal development of the plasma membrane was noted in the elongated cells formed in the presence of 1 μg/ml myxin. Except for the lack of septation during the first 60 min, the filamentous forms appeared normal with well-defined nuclear bodies distributed throughout the cell.

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