Genetic Study of Piliation in Escherichia coli: Implications for Understanding Microbe-Host Interactions at the Molecular Level

1987 ◽  
Vol 6 (2) ◽  
pp. 82-92 ◽  
Author(s):  
Paul E. Orndorff
Keyword(s):  
Escherichia Coli ◽  
Genetic Study ◽  
Molecular Level ◽  
Host Interactions

Elucidating sequence and solvent specific design targets to protect and stabilize enzymes for biocatalysis in ionic liquids

2017 ◽  
Vol 19 (26) ◽  
pp. 17426-17433 ◽  
Author(s):  
K. G. Sprenger ◽  
J. G. Plaks ◽  
J. L. Kaar ◽  
J. Pfaendtner
Keyword(s):  
Ionic Liquids ◽  
Structure Function ◽  
Molecular Level ◽  
Specific Design ◽  
Host Environment ◽  
Host Interactions

For many different frameworks, the structure, function, and dynamics of an enzyme is largely determined by the nature of its interactions with the surrounding host environment, thus a molecular level understanding of enzyme/host interactions is essential to the design of new processes and applications.

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

scholarly journals TcsL Is an Essential Virulence Factor inClostridium sordelliiATCC 9714

2011 ◽  
Vol 79 (3) ◽  
pp. 1025-1032 ◽  
Author(s):  
Glen P. Carter ◽  
Milena M. Awad ◽  
Yibai Hao ◽  
Tennille Thelen ◽  
Ingrid L. Bergin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factor ◽  
Reference Strain ◽  
Molecular Level ◽  
Mortality Rates ◽  
The Other ◽  
Strain Atcc ◽  
Human Pathogen ◽  
Uterine Infection ◽  
Major Virulence Factor

ABSTRACTClostridium sordelliiis an important pathogen of humans and animals, causing a range of diseases, including myonecrosis, sepsis, and shock. Although relatively rare in humans, the incidence of disease is increasing, and it is associated with high mortality rates, approaching 70%. Currently, very little is known about the pathogenesis ofC. sordelliiinfections or disease. Previous work suggested that the lethal large clostridial glucosylating toxin TcsL is the major virulence factor, but a lack of genetic tools has hindered our ability to conclusively assign a role for TcsL or, indeed, any of the other putative virulence factors produced by this organism. In this study, we have developed methods for the introduction of plasmids intoC. sordelliiusing RP4-mediated conjugation fromEscherichia coliand have successfully used these techniques to insertionally inactivate thetcsLgene in the reference strain ATCC 9714, using targetron technology. Virulence testing revealed that the production of TcsL is essential for the development of lethal infections byC. sordelliiATCC 9714 and also contributes significantly to edema seen during uterine infection. This study represents the first definitive identification of a virulence factor inC. sordelliiand opens the way for in-depth studies of this important human pathogen at the molecular level.

scholarly journals Feedback Inhibition of Chorismate Mutase/Prephenate Dehydrogenase (TyrA) of Escherichia coli: Generation and Characterization of Tyrosine-Insensitive Mutants

2005 ◽  
Vol 71 (11) ◽  
pp. 7224-7228 ◽  
Author(s):  
Tina Lütke-Eversloh ◽  
Gregory Stephanopoulos
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Molecular Level ◽  
Feedback Inhibition ◽  
Feedback Regulation ◽  
The Other ◽  
Chorismate Mutase ◽  
Amino Acid Substitutions ◽  
Prephenate Dehydrogenase

ABSTRACT In order to get insights into the feedback regulation by tyrosine of the Escherichia coli chorismate mutase/prephenate dehydrogenase (CM/PDH), which is encoded by the tyrA gene, feedback-inhibition-resistant (fbr) mutants were generated by error-prone PCR. The tyrA fbr mutants were selected by virtue of their resistance toward m-fluoro-d,l-tyrosine, and seven representatives were characterized on the biochemical as well as on the molecular level. The PDH activities of the purified His6-tagged TyrA proteins exhibited up to 35% of the enzyme activity of TyrAWT, but tyrosine did not inhibit the mutant PDH activities. On the other hand, CM activities of the TyrAfbr mutants were similar to those of the TyrAWT protein. Analyses of the DNA sequences of the tyrA genes revealed that tyrA fbr contained amino acid substitutions either at Tyr263 or at residues 354 to 357, indicating that these two sites are involved in the feedback inhibition by tyrosine.

Transcriptional takeover by σ appropriation: remodelling of the σ 70 subunit of Escherichia coli RNA polymerase by the bacteriophage T4 activator MotA and co-activator AsiA

Microbiology ◽  
2005 ◽  
Vol 151 (6) ◽  
pp. 1729-1740 ◽  
Author(s):  
Deborah M. Hinton ◽  
Suchira Pande ◽  
Neelowfar Wais ◽  
Xanthia B. Johnson ◽  
Madhavi Vuthoori ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Molecular Level ◽  
Bacteriophage T4 ◽  
Good Match ◽  
Promoter Sequences ◽  
Recognition Element ◽  
Upstream Promoter ◽  
Promoter Specificity ◽  
Promoter Dna

Activation of bacteriophage T4 middle promoters, which occurs about 1 min after infection, uses two phage-encoded factors that change the promoter specificity of the host RNA polymerase. These phage factors, the MotA activator and the AsiA co-activator, interact with the σ 70 specificity subunit of Escherichia coli RNA polymerase, which normally contacts the −10 and −35 regions of host promoter DNA. Like host promoters, T4 middle promoters have a good match to the canonical σ 70 DNA element located in the −10 region. However, instead of the σ 70 DNA recognition element in the promoter's −35 region, they have a 9 bp sequence (a MotA box) centred at −30, which is bound by MotA. Recent work has begun to provide information about the MotA/AsiA system at a detailed molecular level. Accumulated evidence suggests that the presence of MotA and AsiA reconfigures protein–DNA contacts in the upstream promoter sequences, without significantly affecting the contacts of σ 70 with the −10 region. This type of activation, which is called ‘σ appropriation’, is fundamentally different from other well-characterized models of prokaryotic activation in which an activator frequently serves to force σ 70 to contact a less than ideal −35 DNA element. This review summarizes the interactions of AsiA and MotA with σ 70, and discusses how these interactions accomplish the switch to T4 middle promoters by inhibiting the typical contacts of the C-terminal region of σ 70, region 4, with the host −35 DNA element and with other subunits of polymerase.

scholarly journals Polar Localization of the Autotransporter Family of Large Bacterial Virulence Proteins

2006 ◽  
Vol 188 (13) ◽  
pp. 4841-4850 ◽  
Author(s):  
Sumita Jain ◽  
Peter van Ulsen ◽  
Inga Benz ◽  
M. Alexander Schmidt ◽  
Rachel Fernandez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shigella Flexneri ◽  
Bacterial Pathogen ◽  
Gram Negative ◽  
Virulence Proteins ◽  
Host Interactions ◽  
Polar Localization ◽  
Associated Proteins ◽  
Molecular Information ◽  
Gram Negative Organisms

ABSTRACT Autotransporters are an extensive family of large secreted virulence-associated proteins of gram-negative bacteria. Secretion of such large proteins poses unique challenges to bacteria. We demonstrate that autotransporters from a wide variety of rod-shaped pathogens, including IcsA and SepA of Shigella flexneri, AIDA-I of diffusely adherent Escherichia coli, and BrkA of Bordetella pertussis, are localized to the bacterial pole. The restriction of autotransporters to the pole is dependent on the presence of a complete lipopolysaccharide (LPS), consistent with known effects of LPS composition on membrane fluidity. Newly synthesized and secreted BrkA is polar even in the presence of truncated LPS, and all autotransporters examined are polar in the cytoplasm prior to secretion. Together, these findings are consistent with autotransporter secretion occurring at the poles of rod-shaped gram-negative organisms. Moreover, NalP, an autotransporter of spherically shaped Neisseria meningitidis contains the molecular information to localize to the pole of Escherichia coli. In N. meningitidis, NalP is secreted at distinct sites around the cell. These data are consistent with a model in which the secretion of large autotransporters occurs via specific conserved pathways located at the poles of rod-shaped bacteria, with profound implications for the underlying physiology of the bacterial cell and the nature of bacterial pathogen-host interactions.

Bacterial and host interactions during the biogenesis, toxicity and immunogenicity of Escherichia coli heat-labile enterotoxin

1994 ◽  
Vol 22 (2) ◽  
pp. 306-309 ◽  
Author(s):  
Timothy R. Hirst ◽  
Toufic O. Nashar ◽  
Simon Eaglestone ◽  
Wayne I. Lencer ◽  
Helen M. Webb ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Host Interactions ◽  
Heat Labile

scholarly journals An Overview of the Elusive Passenger in the Gastrointestinal Tract of Cattle: The Shiga Toxin Producing Escherichia coli

2020 ◽  
Vol 8 (6) ◽  
pp. 877 ◽  
Author(s):  
Panagiotis Sapountzis ◽  
Audrey Segura ◽  
Mickaël Desvaux ◽  
Evelyne Forano
Keyword(s):  
Escherichia Coli ◽  
Gut Microbiota ◽  
Foodborne Pathogens ◽  
Shiga Toxin ◽  
Treatment Options ◽  
Animal Husbandry ◽  
Microbiota Composition ◽  
Host Interactions ◽  
Native Cattle ◽  
Gut Microbiota Composition

For approximately 10,000 years, cattle have been our major source of meat and dairy. However, cattle are also a major reservoir for dangerous foodborne pathogens that belong to the Shiga toxin-producing Escherichia coli (STEC) group. Even though STEC infections in humans are rare, they are often lethal, as treatment options are limited. In cattle, STEC infections are typically asymptomatic and STEC is able to survive and persist in the cattle GIT by escaping the immune defenses of the host. Interactions with members of the native gut microbiota can favor or inhibit its persistence in cattle, but research in this direction is still in its infancy. Diet, temperature and season but also industrialized animal husbandry practices have a profound effect on STEC prevalence and the native gut microbiota composition. Thus, exploring the native cattle gut microbiota in depth, its interactions with STEC and the factors that affect them could offer viable solutions against STEC carriage in cattle.

Electron microscope studies of the isolated dna fragments containing biotin genes of escherichia coli k12

1978 ◽  
Vol 36 (2) ◽  
pp. 198-199
Author(s):  
C.K. DasGupta ◽  
H. Samanta ◽  
A. Guha
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Electron Microscope ◽  
Linkage Map ◽  
Molecular Level ◽  
Present Report ◽  
Biosynthetic Enzymes ◽  
Electron Microscopic ◽  
Phage Dna

The genes coding for the biotin biosynthetic enzymes, bioABFCD are located at 17 min of the linkage map of EL coli K12 (Bachman, et al. Bact. Rev. 40: 116, 1976). It was shown that the bioA gene is oriented anticlockwise and the bioBFCD genes are oriented clockwise in the EL coli map, with the bio regulator region lying in between them (Guha et al. J. Mol. Biol. 56: 53, 1971). The study of the control elements of this divergently oriented operon at the molecular level is important for understanding the various intriguing mechanisms of gene expression in bacteria. In the present work, the electron microscopic characterization of the entire biotin genes and its regulator segment isolated after cleaving a biotin transducing phage DNA by restriction endonucleases, is described. The isolated biotin DNA fratments were subsequently recombined with the colEI DNA to isolate a colEl-biotin DNA hybrid. The present report also includes a portion of the study of this cloned plasmid chimera in a biotin auxotroph.

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
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