scholarly journals Asymmetric Cell Growth and Nucleoid Displacement inEscherichia coli

2019 ◽  
Author(s):  
Manasi S. Gangan ◽  
Chaitanya A. Athale
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
Single Cells ◽  
Bacterial Cell Division ◽  
E Coli ◽  
Daughter Cells ◽  
Membrane Growth ◽  
Specific Proteins ◽  
Membrane Addition ◽  
The Asymmetry

ABSTRACTSingle celled growth ofEscherichia coliis typically considered as an example symmetric division, based on the sizes of daughter cells and precision of center finding of the septum. Here, we investigate the symmetry of membrane addition in the mid-plane and DNA segregation using a video-microscopy approach. We find the membrane expansion dynamics to be asymmetric based on mid-cell photobleaching landmarks in FM4-64, used to stain the membrane. The apparent growth bias ofE. colidoes not correspond to the age of the pole. We find the membrane growth asymmetry is correlated to nucleoid displacement, consistent with ideas of coupling of cell growth and nucleoid positioning. The mobility of the actin-homolog MreB also correlates with membrane growth asymmetry, based on fluorescence recovery after photobleaching (FRAP) measurements of a YFP-fusion. These correlations suggest the small asymmetry of membrane addition observed could potentially drive nucleoid segregation and MreB mobility asymmetry inE. coli.IMPORTANCEAsymmetry in bacterial cell division is seen in it’s most simple form in the binomial event of protein segregation that results in ‘noise’ in equal segregation and depends on the protein copy number. In the case of specific proteins this can also affect growth, and result in differentiation. However, during the asexual division ofEscherichia colisingle cells are thought to grow symmetrically and divide equally. We find a slight but consistent asymmetry in growth based on quantitative morphometry of cell pole displacement in time-series of growingE. colicells. Increased cell wall extension in one half of the cell over the other appears to explain the asymmetry in the displacement of cell poles. Interestingly the growth asymmetry is not correlated to the age of the pole (old and new). This observed asymmetry appears to correlate with the asymmetry of nucleoid segregation, resulting in the nucleoids finding the midpoints of the respective daughter cells, and formation of the septum at the geometric centre of the elongated cell just prior to division. The mobility dynamics of the cytoskeletal protein MreB, which organizes the cell membrane, is are more dynamic where membrane growth is faster. Thus we propose a linkage between this observed growth asymmetry and that of MreB dynamics.

scholarly journals Artificial Septal Targeting of Bacillus subtilis Cell Division Proteins in Escherichia coli: an Interspecies Approach to the Study of Protein-Protein Interactions in Multiprotein Complexes

2008 ◽  
Vol 190 (18) ◽  
pp. 6048-6059 ◽  
Author(s):  
Carine Robichon ◽  
Glenn F. King ◽  
Nathan W. Goehring ◽  
Jon Beckwith
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Cell Division ◽  
Protein Interactions ◽  
Fluorescent Protein ◽  
Bacterial Cell Division ◽  
Protein Protein Interactions ◽  
Positive Interaction ◽  
E Coli ◽  
Multiprotein Complexes

ABSTRACT Bacterial cell division is mediated by a set of proteins that assemble to form a large multiprotein complex called the divisome. Recent studies in Bacillus subtilis and Escherichia coli indicate that cell division proteins are involved in multiple cooperative binding interactions, thus presenting a technical challenge to the analysis of these interactions. We report here the use of an E. coli artificial septal targeting system for examining the interactions between the B. subtilis cell division proteins DivIB, FtsL, DivIC, and PBP 2B. This technique involves the fusion of one of the proteins (the “bait”) to ZapA, an E. coli protein targeted to mid-cell, and the fusion of a second potentially interacting partner (the “prey”) to green fluorescent protein (GFP). A positive interaction between two test proteins in E. coli leads to septal localization of the GFP fusion construct, which can be detected by fluorescence microscopy. Using this system, we present evidence for two sets of strong protein-protein interactions between B. subtilis divisomal proteins in E. coli, namely, DivIC with FtsL and DivIB with PBP 2B, that are independent of other B. subtilis cell division proteins and that do not disturb the cytokinesis process in the host cell. Our studies based on the coexpression of three or four of these B. subtilis cell division proteins suggest that interactions among these four proteins are not strong enough to allow the formation of a stable four-protein complex in E. coli in contrast to previous suggestions. Finally, our results demonstrate that E. coli artificial septal targeting is an efficient and alternative approach for detecting and characterizing stable protein-protein interactions within multiprotein complexes from other microorganisms. A salient feature of our approach is that it probably only detects the strongest interactions, thus giving an indication of whether some interactions suggested by other techniques may either be considerably weaker or due to false positives.

scholarly journals Erosion and Subsequent Transport State of Escherichia coli from Cowpats

2005 ◽  
Vol 71 (6) ◽  
pp. 2875-2879 ◽  
Author(s):  
Richard William Muirhead ◽  
Robert Peter Collins ◽  
Philip James Bremer
Keyword(s):  
Escherichia Coli ◽  
Surface Waters ◽  
Overland Flow ◽  
Single Cells ◽  
Rainfall Event ◽  
Buffer Strips ◽  
Simulated Rainfall ◽  
E Coli ◽  
Unattached Fraction ◽  
Over Time

ABSTRACT Processes by which fecal bacteria enter overland flow and their transportation state to surface waters are poorly understood, making the effectiveness of measures designed to intercept this pathway, such as vegetated buffer strips, difficult to predict. Freshly made and aged (up to 30 days) cowpats were exposed to simulated rainfall, and samples of the cowpat material and runoff were collected. Escherichia coli in the runoff samples were separated into attached (to particles) and unattached fractions, and the unattached fraction was analyzed to determine if the cells were clumped. Within cowpats, E. coli grew for 6 to 14 days, rather than following a typical logarithmic die-off curve. E. coli numbers in the runoff correlated with numbers inside the cowpat. Most of the E. coli organisms eroded from the cowpats were transported as single cells, and only a small percentage (about 8%) attached to particles. The erosion of E. coli from cowpats and the state in which the cells were transported did not vary with time within a single rainfall event or over time as the cowpats aged and dried out. These findings indicate that cowpats can remain a significant source of E. coli in overland flow for more than 30 days. As well, most of the E. coli organisms eroded from cowpats will occur as readily transportable single cells.

scholarly journals Of the Morphogenes that Make a Ring, A Rod and a Sphere in Escherichia Coli

2007 ◽  
Vol 90 (2-3) ◽  
pp. 59-72 ◽  
Author(s):  
Medhatm Khattar ◽  
Issmat I. Kassem ◽  
Ziad W. El-Hajj
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Bacterial Cell ◽  
Bacterial Cell Division ◽  
Antibacterial Compounds ◽  
E Coli ◽  
The Past ◽  
New Knowledge ◽  
Fundamental Process ◽  
Simple Question

In 1993, William Donachie wrote “The success of molecular genetics in the study of bacterial cell division has been so great that we find ourselves, armed with much greater knowledge of detail, confronted once again with the same naive questions that we set to answer in the first place”1. Indeed, attempts to answer the apparently simple question of how a bacterial cell divides have led to a wealth of new knowledge, in particular over the past decade and a half. And while some questions have been answered to a great extent since the early reports of isolation of division mutants of Escherichia coli2,3, some key pieces of the puzzle remain elusive. In addition to it being a fundamental process in bacteria that merits investigation in its own right, studying the process of cell division offers an abundance of new targets for the development of new antibacterial compounds that act directly against key division proteins and other components of the cytoskeleton, which are encoded by the morphogenes of E. coli4. This review aims to present the reader with a snapshot summary of the key players in E. coli morphogenesis with emphasis on cell division and the rod to sphere transition.

scholarly journals Staphylococcus aureus MazF Specifically Cleaves a Pentad Sequence, UACAU, Which Is Unusually Abundant in the mRNA for Pathogenic Adhesive Factor SraP

2009 ◽  
Vol 191 (10) ◽  
pp. 3248-3255 ◽  
Author(s):  
Ling Zhu ◽  
Koichi Inoue ◽  
Satoshi Yoshizumi ◽  
Hiroshi Kobayashi ◽  
Yonglong Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Cell Growth ◽  
Bioinformatics Analysis ◽  
Human Tissues ◽  
Regulatory Relationship ◽  
E Coli ◽  
Pathogenic Factors ◽  
Inhibit Cell Growth ◽  
Adhesive Factor

ABSTRACT Escherichia coli mRNA interferases, such as MazF and ChpBK, are sequence-specific endoribonucleases encoded by toxin-antitoxin (TA) systems present in its genome. A MazF homologue in Staphylococcus aureus (MazFSa) has been shown to inhibit cell growth when induced in E. coli. Here, we determined the cleavage site for MazFSa with the use of phage MS2 RNA as a substrate and CspA, an RNA chaperone, which prevents the formation of secondary structures in the RNA substrate. MazFSa specifically cleaves the RNA at a pentad sequence, U↓ACAU. Bioinformatics analysis revealed that this pentad sequence is significantly abundant in several genes, including the sraP gene in the S. aureus N315 strain. This gene encodes a serine-rich protein, which is known to play an important role in adhesion of the pathogen to human tissues and thus in endovascular infection. We demonstrated that the sraP mRNA became extremely unstable in comparison with the ompA mRNA only when MazFSa was induced in E. coli. Further bioinformatics analysis indicated that the pentad sequence is also significantly abundant in the mRNAs for all the pathogenic factors in S. aureus. This observation suggests a possible regulatory relationship between the MazEFSa TA module and the pathogenicity in S. aureus.

scholarly journals In Vivo Modulation of a DnaJ Homolog, CbpA, by CbpM

2007 ◽  
Vol 189 (9) ◽  
pp. 3635-3638 ◽  
Author(s):  
Matthew R. Chenoweth ◽  
Nancy Trun ◽  
Sue Wickner
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
Stationary Phase ◽  
Specific Inhibitor ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
E Coli ◽  
Hsp70 Chaperone

ABSTRACT CbpA, an Escherichia coli DnaJ homolog, can function as a cochaperone for the DnaK/Hsp70 chaperone system, and its in vitro activity can be modulated by CbpM. We discovered that CbpM specifically inhibits the in vivo activity of CbpA, preventing it from functioning in cell growth and division. Furthermore, we have shown that CbpM interacts with CbpA in vivo during stationary phase, suggesting that the inhibition of activity is a result of the interaction. These results reveal that the activity of the E. coli DnaK system can be regulated in vivo by a specific inhibitor.

scholarly journals Reciprocal Regulation of l-Arabinose and d-Xylose Metabolism in Escherichia coli

2015 ◽  
Vol 198 (3) ◽  
pp. 386-393 ◽  
Author(s):  
Santosh Koirala ◽  
Xiaoyi Wang ◽  
Christopher V. Rao
Keyword(s):  
Escherichia Coli ◽  
Plant Biomass ◽  
Single Cells ◽  
Xylose Utilization ◽  
Xylose Metabolism ◽  
Reciprocal Regulation ◽  
Content Type ◽  
E Coli ◽  
Metabolic Genes ◽  
Mixed Populations

ABSTRACTGlucose is known to inhibit the transport and metabolism of many sugars inEscherichia coli. This mechanism leads to its preferential consumption. Far less is known about the preferential utilization of nonglucose sugars inE. coli. Two exceptions arel-arabinose andd-xylose. Previous studies have shown thatl-arabinose inhibitsd-xylose metabolism inEscherichia coli. This repression results froml-arabinose-bound AraC binding to the promoter of thed-xylose metabolic genes and inhibiting their expression. This mechanism, however, has not been explored in single cells. Both thel-arabinose andd-xylose utilization systems are known to exhibit a bimodal induction response to their cognate sugar, where mixed populations of cells either expressing the metabolic genes or not are observed at intermediate sugar concentrations. This suggests thatl-arabinose can only inhibitd-xylose metabolism inl-arabinose-induced cells. To understand how cross talk between these systems affects their response, we investigatedE. coliduring growth on mixtures ofl-arabinose andd-xylose at single-cell resolution. Our results showed that mixed, multimodal populations ofl-arabinose- andd-xylose-induced cells occurred at intermediate sugar concentrations. We also found thatd-xylose inhibited the expression of thel-arabinose metabolic genes and that this repression was due to XylR. These results demonstrate that a strict hierarchy does not exist betweenl-arabinose andd-xylose as previously thought. The results may also aid in the design ofE. colistrains capable of simultaneous sugar consumption.IMPORTANCEGlucose,d-xylose, andl-arabinose are the most abundant sugars in plant biomass. Developing efficient fermentation processes that convert these sugars into chemicals and fuels will require strains capable of coutilizing these sugars. Glucose has long been known to repress the expression of thel-arabinose andd-xylose metabolic genes inEscherichia coli. Recent studies found thatl-arabinose also represses the expression of thed-xylose metabolic genes. In the present study, we found thatd-xylose also represses the expression of thel-arabinose metabolic genes, leading to mixed populations of cells capable of utilizingl-arabinose andd-xylose. These results further our understanding of mixed-sugar utilization and may aid in strain design.

scholarly journals Possible epigenetic influence on cellular differentiation and lineage segregation in Escherichia coli

2019 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Cell Growth ◽  
Single Cell ◽  
Cell Fate ◽  
Cellular Differentiation ◽  
Environmental Stressors ◽  
Epigenetic Markers ◽  
E Coli ◽  
Growth Chambers

Epigenetics provides the critical connection between environmental influence and gene expression, where environmental stressors could modulate expression of specific genes in particular scenarios using molecular markers etched at the genome level. Hence, epigenetics likely play important roles in potentiating the development of specific lineages, cell fate or cellular differentiation. For example, when specific environmental stressor is present, epigenetic markers in the genome receive a signal for either activating or deactivating expression of particular sets of genes, which may be linked to the developmental trajectory of the organism. Using Escherichia coli as model organism, a possible study may investigate the role of epigenetics in influencing cellular differentiation of the bacterium. Specifically, a single E. coli cell would be propagated into a consortium of 12 or more bacterial cells in a microfluidics growth chamber. Genetic material extracted would be sent for single cell genomics, transcriptomics, and chromatin immunoprecipitation sequencing (ChIP-seq). After profiling, the residual population would be diverted by microchannels to 6 different cell growth chambers, where they would be cultivated under identical conditions for understanding possible triggers to cell differentiation. At suitable time points of 2, 4, 6, 8, 10, 12 hours, single cell would be extracted from each growth chamber for profiling single cell genomics, transcriptomics, and epigenetics markers. Optical and confocal laser scanning microscopy would provide readout of cell morphologies. Comparison of the readout between the original clonal population and those of the different growth chambers may provide important points for correlating epigenetic markers with gene expression and phenotypic readout in cell lineage, fate and differentiation. In subsequent experiments, different environmental stressors such as pH, imbalance nutrient composition between carbon and nitrogen, nanoparticles or heavy metals, could be used as triggers for specific cell growth response guided by epigenetic programmes embedded within the epigenome of the bacterium. Collectively, epigenetics hold influence for cellular differentiation in view of specific environmental stressors, where epigenetic markers on the genome communicate specific environmental factor's effect on the organism through altering expression of particular sets of genes, that result in different cell fate, lineage and differentiation. Using modern single cell techniques at the genomics, transcriptomics and epigenomics level, the study hopes to elucidate epigenetic potentiators of cellular differentiation in E. coli with and without environmental stressors such as nutrient deprivation, pH and toxic metals.

scholarly journals Reproducing bench-scale cell growth and productivity

2018 ◽  
Author(s):  
Ariel Hecht ◽  
James Filliben ◽  
Sarah A. Munro ◽  
Marc Salit
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
Small Molecule ◽  
Fluorescent Protein ◽  
Fractional Factorial ◽  
Red Fluorescent Protein ◽  
Factorial Experiments ◽  
Minimum Information ◽  
E Coli ◽  
Product Titer

Reproducing, exchanging, comparing, and building on each other’s work is foundational to technology advances.1Advancing biotechnology calls for reliable reuse of engineered strains.2Reliable reuse of engineered strains requires reproducible growth and productivity. To demonstrate reproducibility for biotechnology, we identified the experimental factors that have the greatest effect on the growth and productivity of our engineered strains.3–6We present a draft of a Minimum Information Standard for Engineered Organism Experiments (MIEO) based on this method. We evaluated the effect of 22 factors onEscherichia coli(E. coli) engineered to produce the small molecule lycopene, and 18 factors onE. coliengineered to produce red fluorescent protein (RFP). Container geometry and shaking had the greatest effect on product titer and yield. We reproduced our results under two different conditions of reproducibility:7conditions of use (different fractional factorial experiments), and time (48 biological replicates performed on 12 different days over four months).

scholarly journals Production of soluble regulatory hydrogenase from Ralstonia eutropha in Escherichia coli using a fed-batch-based autoinduction system

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Qin Fan ◽  
Peter Neubauer ◽  
Matthias Gimpel
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
Protein Production ◽  
Ralstonia Eutropha ◽  
Process Time ◽  
Synthesis Rate ◽  
Heterologous Production ◽  
Fed Batch ◽  
Iptg Induction ◽  
E Coli

Abstract Background Autoinduction systems can regulate protein production in Escherichia coli without the need to monitor cell growth or add inducer at the proper time following culture growth. Compared to classical IPTG induction, autoinduction provides a simple and fast way to obtain high protein yields. In the present study, we report on the optimization process for the enhanced heterologous production of the Ralstonia eutropha regulatory hydrogenase (RH) in E. coli using autoinduction. These autoinduction methods were combined with the EnPresso B fed-batch like growth system, which applies slow in situ enzymatic glucose release from a polymer to control cell growth and protein synthesis rate. Results We were able to produce 125 mg L−1 RH corresponding to a productivity averaged over the whole process time of 3 mg (L h)−1 in shake flasks using classic single-shot IPTG induction. IPTG autoinduction resulted in a comparable volumetric RH yield of 112 mg L−1 and due to the shorter overall process time in a 1.6-fold higher productivity of 5 mg (L h)−1. In contrast, lactose autoinduction increased the volumetric yield more than 2.5-fold and the space time yield fourfold reaching 280 mg L−1 and 11.5 mg (L h)−1, respectively. Furthermore, repeated addition of booster increased RH production to 370 mg L−1, which to our knowledge is the highest RH concentration produced in E. coli to date. Conclusions The findings of this study confirm the general feasibility of the developed fed-batch based autoinduction system and provide an alternative to conventional induction systems for efficient recombinant protein production. We believe that the fed-batch based autoinduction system developed herein will favor the heterologous production of larger quantities of difficult-to-express complex enzymes to enable economical production of these kinds of proteins.

scholarly journals Effect of different aeration and polyethylene glycol concentration on growth of Escherichia coli DH5α in a 1L bioreactor

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Escherichia Coli ◽  
Polyethylene Glycol ◽  
Cell Growth ◽  
Growth Medium ◽  
Growth Rates ◽  
Shake Flask ◽  
Foam Formation ◽  
Biomass Formation ◽  
E Coli ◽  
Toxicity Effect

Large culture volume in bioreactor necessitates aeration for providing sufficient oxygen for cell growth. Thus, extend of aeration and amount of anti-foam needed for suppressing foam formation are key parameters determining the success of bioreactor fermentation. Specifically, while aeration provides more oxygen for powering cellular metabolism and could lead to faster growth rate and more efficient metabolism, it also introduces greater shear stress, mixing and foam formation. On the other hand, anti-foaming agents such as polyethylene glycol (PEG) could exert a toxicity effect on cells as well as introducing increased osmolarity and viscosity that could hamper cell growth. In this preliminary study, effect of different PEG concentrations and extent of aeration on growth of Escherichia coli DH5α (ATCC 53868) in a 1L bioreactor at 37 oC with LB Lennox growth medium was investigated. Experiment results revealed that E. coli DH5α growth in bioreactor at 1 VVM aeration with 1 g/L PEG was faster than that in a 250 mL glass shake flask, and with greater secretion of alkaline metabolites. Similar optical density obtained between bioreactor and shake flask cultivation pointed to the maximized utilization of growth medium nutrients for biomass formation. Increase in bioreactor aeration to 3 VVM at 1 g/L PEG, however, resulted in increased secretion of acidic metabolites into the culture broth while allowing similar maximal optical density to be obtained compared to aeration of 1 VVM at 1 g/L PEG. This indicated that E. coli DH5α was able to adapt to physiological impacts from increased aeration and highlighted that no significant metabolic energy was diverted from biomass formation. Finally, increase in PEG concentration to 10 g/L from 1 g/L did not introduce additional toxicity effect given that growth profile of E. coli DH5α under the two PEG concentrations overlapped each other. However, observations of reduced secretion of acidic metabolites at the outset of growth in 10 g/L PEG pointed to physiological impacts that did not affect growth rates and biomass formation. Collectively, E. coli DH5α was able to tolerate enhanced aeration of 3 VVM and 10 g/L PEG anti-foam without significant detrimental impacts on growth rates and biomass formation.

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