scholarly journals Molecular genetic analysis of ganglioside GD1b-binding activity of Escherichia coli type IIa heat-labile enterotoxin by use of random and site-directed mutagenesis.

1992 ◽  
Vol 60 (1) ◽  
pp. 63-70 ◽  
Author(s):  
T D Connell ◽  
R K Holmes
Keyword(s):  
Escherichia Coli ◽  
Genetic Analysis ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Binding Activity ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Heat Labile

scholarly journals A genetically detoxified derivative of heat-labile Escherichia coli enterotoxin induces neutralizing antibodies against the A subunit.

1994 ◽  
Vol 180 (6) ◽  
pp. 2147-2153 ◽  
Author(s):  
M Pizza ◽  
M R Fontana ◽  
M M Giuliani ◽  
M Domenighini ◽  
C Magagnoli ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cholera Toxin ◽  
Neutralizing Antibodies ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
E Coli ◽  
Heat Labile ◽  
A Subunit ◽  
Adp Ribosyltransferase ◽  
Derivatives Of

Escherichia coli enterotoxin (LT) and the homologous cholera toxin (CT) are A-B toxins that cause travelers' diarrhea and cholera, respectively. So far, experimental live and killed vaccines against these diseases have been developed using only the nontoxic B portion of these toxins. The enzymatically active A subunit has not been used because it is responsible for the toxicity and it is reported to induce a negligible titer of toxin neutralizing antibodies. We used site-directed mutagenesis to inactivate the ADP-ribosyltransferase activity of the A subunit and obtained nontoxic derivatives of LT that elicited a good titer of neutralizing antibodies recognizing the A subunit. These LT mutants and equivalent mutants of CT may be used to improve live and killed vaccines against cholera and enterotoxinogenic E. coli.

scholarly journals Molecular genetic analysis of the Escherichia coli phoP locus.

1992 ◽  
Vol 174 (2) ◽  
pp. 486-491 ◽  
Author(s):  
E A Groisman ◽  
F Heffron ◽  
F Solomon
Keyword(s):  
Escherichia Coli ◽  
Genetic Analysis ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis

Molecular genetic analysis of Escherichia coli type I adhesins

2006 ◽  
Vol 141 (3) ◽  
pp. 339-342 ◽  
Author(s):  
V. A. Beskhlebnaya ◽  
E. V. Trinchina ◽  
P. Aprikyan ◽  
V. Chesnokova ◽  
E. V. Sokurenko
Keyword(s):  
Escherichia Coli ◽  
Genetic Analysis ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Type I

scholarly journals Functional Consequences of Changing Proline Residues in the Phenylalanine-Specific Permease ofEscherichia coli

1998 ◽  
Vol 180 (21) ◽  
pp. 5515-5519 ◽  
Author(s):  
Jing Pi ◽  
C. Dogovski ◽  
A. J. Pittard
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Genetic Analysis ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Transport Activity ◽  
Functional Importance ◽  
Transmembrane Segments ◽  
High Affinity ◽  
Functional Consequences

ABSTRACT The PheP protein is a high-affinity phenylalanine-specific permease of the bacterium Escherichia coli. A topological model based on genetic analysis involving the construction of protein fusions with alkaline phosphatase has previously been proposed in which PheP has 12 transmembrane segments with both N and C termini located in the cytoplasm (J. Pi and A. J. Pittard, J. Bacteriol. 178:2650–2655, 1996). Site-directed mutagenesis has been used to investigate the functional importance of each of the 16 proline residues of the PheP protein. Replacement of alanine at only three positions, P54, P341, and P442, resulted in the loss of 50% or more activity. Substitutions at P341 had the most dramatic effects. None of these changes in transport activity were, however, associated with any defect of the mutant protein in inserting into the membrane, as indicated by [35S]methionine labelling and immunoprecipitation using anti-PheP serum. A possible role for each of these three prolines is discussed. Inserting a single alanine residue at different sites within span IX and the loop immediately preceding it also had major effects on transport activity, suggesting an important role for a highly organized structure in this region of the protein.

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