Escherichia coli LT enterotoxin subunit A demonstrate partial toxicity independent of the nicking around Arg192

Article Abstract:

The capacity of Escherichia coli heat-labile enterotoxin (LT) subunit A to induce cyclic AMP and generate partial toxicity in the absence of Arg192 nicking was demonstrated. Comparison of biological activity of each mutant toxin by the rabbit skin permeability (PF) test and carbohydrate (CHO) cell assay results revealed that another pathway is involved in which the abnormal A subunit activates adenylate cyclase. Also, an abnormal A subunit might directly activate adenylate cyclase with or without ADP-ribosyltransferase.

Enterotoxins, Amino acid sequence, Amino acid sequencing

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Cra-mediated regulation of Escherichia coli adenylate cyclase

Article Abstract:

The genetic factors that regulate adenylate cyclase (AC) synthesis were analyzed in Escherichia coli cra mutant strains grown in a fructose nutrient medium. Analysis of the role of cra gene in AC synthesis by Escherichia coli indicated the presence of different AC levels in wild-type and cra mutant strains. The variation in Ac levels was due to the inability of phosphorylated glucose-specific IIA protein to activate AC in the absence of cra gene which regulates the expression of fructose operons.

Genetic aspects, Microbiological synthesis, Operons, Adenylate cyclase, Fructose

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cAMP-cAMP receptor protein complex: five binding sites in the control region of the Escherichia coli mannitol operon

Article Abstract:

A study shows that there are five adenosine 3',5' cyclic phosphate (cAMP) receptor protein binding sequences in the control region of mannitol (mtl) operon of Escherichia coli. Using the polymerase chain reaction, a DNA fragment surrounding total mtl operon regulatory region is made. cAMP-cAMP complex is strongly held by four of these binding sequences. The fifth one bound the complex very weakly.

Observations, Binding sites (Biochemistry), Active sites (Biochemistry)

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