The Escherichia coli divisome: born to divide

Author: Natale, P.; Pazos, M.; Vicente, M. Description: Septation in Escherichia coli involves complex molecular mechanisms that contribute to the accuracy of bacterial division. The proto-ring, a complex made up by the FtsZ, FtsA and ZipA proteins, forms at the beginning of the process and directs the assembly of the full divisome. Central to this complex is the FtsZ protein, a GTPase able to assemble into a ring-like structure that responds to several modulatory inputs including mechanisms to position the septum at midcell. The connection with the cell wall synthesising…

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Effect of environmental factors and cell physiological state on Pulsed Electric Fields resistance and repair capacity of various strains of Escherichia coli

Author: Somolinos, M.; Garcia, D.; Manas, P.; Condon, S.; Pagan, R. Description: The aim was to determine the resistance variation of four strains of Escherichia coli to Pulsed Electric Fields (PEF), the role of the sigma factor RpoS in PEF resistance, as well as the influence of several environmental factors and the cell physiological state on the PEF resistance and repair capacity. The rpoS null mutant, E. coli BJ4L1, exhibited decreased PEF resistance as compared with its wild-type parent, BJ4. W3110 and O157:H7 were the most PEF-resistant strains: whereas 2…

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Evolution of Escherichia coli for growth at high temperatures

Author: Rudolph, B.; Gebendorfer, K.M.; Buchner, J.; Winter, J. Description: Evolution depends on the acquisition of genomic mutations that increase cellular fitness. Here, we evolved Escherichia coli MG1655 cells to grow at extreme temperatures. We obtained a maximum growth temperature of 48.5 degrees C, which was not increased further upon continuous cultivation at this temperature for >600 generations. Despite a permanently induced heat shock response in thermoresistant cells, only exquisitely high GroEL/GroES levels are essential for growth at 48.5 degrees C. They depend on the presence of lysyl-tRNA-synthetase, LysU, because…

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Pathogenic Escherichia coli

Author: Kaper, James B.; Nataro, James P.; Mobley, Harry L. Description: Few microorganisms are as versatile as Escherichia coli. An important member of the normal intestinal microflora of humans and other mammals, E. coli has also been widely exploited as a cloning host in recombinant DNA technology. But E. coli is more than just a laboratory workhorse or harmless intestinal inhabitant; it can also be a highly versatile, and frequently deadly, pathogen. Several different E. coli strains cause diverse intestinal and extraintestinal diseases by means of virulence factors that affect…

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Mutations in a temperate bacteriophage affecting its ability to lysogenize Escherichia coli

Author: Kaiser, A.D. Description: Forty independently occurring clear plaque-forming mutants of A have been isolated. Among them three different phenotypes can be recognized. Crosses between mutants indicate that all of the mutant loci are closely linked to one another, occupying a segment of the A linkage group which is about of the total known genetic length. More detailed mapping reveals that the mutant loci fall into three adjacent regions, one for each phenotype. Mixed infection with a pair of phenotypically different mutants, each of which lysogenizes very poorly or not…

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Rapid detection of Escherichia coli using bacteriophage-induced lysis and image analysis

Author: Yang, X.; Wisuthiphaet, N.; Young, G. M. & Nitin, N. Description: Rapid detection of bacterial pathogens is a critical unmet need for both food and environmental samples such as irrigation water. As a part of the Food safety Modernization Act (FSMA), The Produce Safety rule has established several requirements for testing for the presence of generic Escherichia coli in water, but the current method available for testing (EPA M1603) demands specified multiple colony verification and highly trained personnel to perform these tests. The purpose of the study was to…

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Induced expression of the heat shock protein genes uspA and grpE during starvation at low temperatures and their influence on thermal resistance of Escherichia coli O157:H7

Author: Zhang, Y.; Griffiths, M.W. Description: Heat shock proteins play an important role in protecting bacterial cells against several stresses, including starvation. In this study, the promoters for two genes encoding heat shock proteins involved in many stress responses, UspA and GrpE, were fused with the green fluorescent protein (gfp) gene. Thus, the expression of the two genes could be quantified by measuring the fluorescence emitted by the cells under different environmental conditions. The heat resistance levels of starved and nonstarved cells during storage at 5, 10, and 37 degrees…

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Interplay between iron homeostasis and virulence: Fur and RyhB as major regulators of bacterial pathogenicity

Author: Porcheron, Gaelle; Dozois, Charles M. Description: In bacteria-host interactions, competition for iron is critical for the outcome of the infection. As a result of its redox properties, this metal is essential for the growth and proliferation of most living organisms, including pathogenic bacteria. This metal is also potentially toxic, making the precise maintenance of iron homeostasis necessary for survival. Iron acquisition and storage control is mediated in most bacteria by the global ferric uptake regulator (Fur) and iron-responsive small regulatory non-coding RNAs (RyhB in the model organism Escherichia coli)….

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Single-molecule imaging of FtsK translocation reveals mechanistic features of protein-protein collisions on DNA

Author: Lee, Ja Yil; Finkelstein, Ilya J.; Arciszewska, Lidia K.; Sherratt, David J.; Greene, Eric C. Description: In physiological settings, DNA translocases will encounter DNA-bound proteins, which must be dislodged or bypassed to allow continued translocation. FtsK is a bacterial translocase that promotes chromosome dimer resolution and decatenation by activating XerCD-dif recombination. To better understand how translocases act in crowded environments, we used single-molecule imaging to visualize FtsK in real time as it collided with other proteins. We show that FtsK can push, evict, and even bypass DNA-bound proteins. The…

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Microplastic pollution increases gene exchange in aquatic ecosystems

Author: Arias-Andres, Maria; Klumper, Uli; Rojas-Jimenez, Keilor; Grossart, Hans-Peter Description: Pollution by microplastics in aquatic ecosystems is accumulating at an unprecedented scale, emerging as a new surface for biofilm formation and gene exchange. In this study, we determined the permissiveness of aquatic bacteria towards a model antibiotic resistance plasmid, comparing communities that form biofilms on microplastics vs. those that are free-living. We used an exogenous and red-fluorescent E. coli donor strain to introduce the green-fluorescent broad-host-range plasmid pKJK5 which encodes for trimethoprim resistance. We demonstrate an increased frequency of plasmid…

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