A genetic study of Escherichia coli strains carrying Mu-λ-Mu structures

1983 ◽  
Vol 190 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Eleonora S. Piruzian ◽  
Nina G. Koretskaya
Keyword(s):  
Escherichia Coli ◽  
Genetic Study

The pathway of recombining short homologous ends in Escherichia coli revealed by genetic study

2020 ◽  
Author(s):  
Yuqing Yang ◽  
Tianqi Wang ◽  
Qiaoli Yu ◽  
Huaiwei Liu ◽  
Luying Xun ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genetic Study

scholarly journals A Comprehensive View of Translesion Synthesis in Escherichia coli

2020 ◽  
Vol 84 (3) ◽  
Author(s):  
Shingo Fujii ◽  
Robert P. Fuchs
Keyword(s):  
Escherichia Coli ◽  
Genetic Study ◽  
Translesion Synthesis ◽  
Gap Filling ◽  
Lesion Bypass ◽  
Content Type ◽  
Comprehensive View ◽  
Pol V ◽  
Whole Process ◽  
Per Se

The lesion bypass pathway, translesion synthesis (TLS), exists in essentially all organisms and is considered a pathway for postreplicative gap repair and, at the same time, for lesion tolerance. As with the saying “a trip is not over until you get back home,” studying TLS only at the site of the lesion is not enough to understand the whole process of TLS. Recently, a genetic study uncovered that polymerase V (Pol V), a poorly expressed Escherichia coli TLS polymerase, is not only involved in the TLS step per se but also participates in the gap-filling reaction over several hundred nucleotides.

scholarly journals Resistance of Escherichia coli to Penicillins I. Genetic Study of Some Ampicillin-Resistant Mutants

1965 ◽  
Vol 90 (1) ◽  
pp. 54-62 ◽  
Author(s):  
Kerstin G. Eriksson-Grennberg ◽  
Hans G. Boman ◽  
J. A. Torbjörn Jansson ◽  
Sone Thorén
Keyword(s):  
Escherichia Coli ◽  
Genetic Study ◽  
Resistant Mutants

scholarly journals Resistance ofEscherichia colito penicillins: IV. Genetic study of mutants resistant to D, L-ampicillin concentrations of 100 μg/ml.

1968 ◽  
Vol 12 (2) ◽  
pp. 169-185 ◽  
Author(s):  
Hans G. Boman ◽  
Kerstin G. Eriksson-Grennberg ◽  
Staffan Normark ◽  
Eva Matsson
Keyword(s):  
Escherichia Coli ◽  
Chromosomal Aberration ◽  
Resistance Genes ◽  
Genetic Study ◽  
Cell Contact ◽  
Donor Strain ◽  
Ampicillin Resistance ◽  
Resistant Mutants ◽  
Stable Pairs ◽  
Rna Phage

The first two steps towards increasing ampicillin resistance inEscherichia coliconcern the genesampAandampBwhich are located at least 20 min from each other (Eriksson-Grennberget al.1965 and the two preceding papers). This paper describes a third class ofampA-containing mutants (designatedampAB) which are resistant to D, L-ampicillin concentrations of 100 μg/ml. When such as F-strain (D31) was crossed to different Hfr strains analysis of thetrp+andproB+recombinants indicated that resistance genes were located betweentrpandproB. Altogether five classes of recombinants were produced but only the two genesampAandampBwere recovered. One interpretation suggested is that the resistance of D31 is due to the presence ofampAandampBand a chromosomal aberration by whichampAwas moved to a position nearampB. It was possible to transduce both intermediate levels of resistance as well as the full resistance of anampABdonor strain, but the strains produced were unstable. In crosses the presence ofampABin the recipient reduced the number of recombinants by reducing the number of stable pairs. In an Hfr strainampABwas shown to give rise to additional difficulties in establishing the cell contact during mating. Some ampicillin resistant mutants also showed decreased ability to propagate the RNA phage MS2.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Infection of Escherichia coli with bacteriophages

1969 ◽  
Vol 27 ◽  
pp. 370-371
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Cell Surface ◽  
Virus Type ◽  
Infection Process ◽  
Adsorption Site ◽  
The Other ◽  
Specific Receptors ◽  
Bacterial Receptors

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.

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