Identification of an amber uvrC mutant in Escherichia coli K-12.

Identification of an amber uvrC mutant in Escherichia coli K-12.

Endonuclease V (nfi) mutant of Escherichia coli K-12.

Endonuclease V (deoxyinosine 3' endonuclease), the product of the nfi gene, has a specificity that encompasses DNAs containing dIMP, abasic sites, base mismatches, uracil, and even untreated single-stranded DNA. To determine its importance in DNA repair pathways, nfi insertion mutants and overproducers (strains bearing nfi plasmids) were constructed. The mutants displayed a twofold increase in ...

Deletion and amber mutants of fla loci in Escherichia coli K-12.

A rapid screening method for amber fla mutants of E. coli was devised and many mutants were obtained. In addition, strains with deletions of the fla genes in the his-uvrC region were isolated from high-temperature survivors of a lambda cI857 lysogen in which the prophage is located between his and fla. Utilizing these mutants, eleven fla genes (I--XI) and one hag gene were identified in the his...

Overproduction of exopolysaccharides by an Escherichia coli K-12 rpoS mutant in response to osmotic stress.

The yjbEFGH operon is implicated in the production of an exopolysaccharide of an unknown function and is induced by osmotic stress and negatively regulated by the general stress response sigma factor RpoS. Despite the obvious importance of RpoS, negative selection for rpoS has been reported to take place in starved cultures, suggesting an adaptive occurrence allowing the overexpression of RpoD-...

Transduction in Escherichia Coli K-12.

SYSTEM of genetic transduction has been discovered in the sexually fertile A K-12 strain of Escherichia coli. This transduction is mediated by lambda, a temperate phage for which K-12 is normally lysogenic. The distinctive features of the lambda-K-12 system include the following: (1) The transductions are limited to a cluster of genes for galactose fermentation. The GaZ loci are closely linked ...