Survival of Escherichia coli K12 in seawater

Genetic analysis of the histidine operon in Escherichia coli K12.

I N Salmonella typhimurium a cluster of nine genes, behaving as a single operon (AMES and GARRY 1959) specify the enzymes which carry out the ten reactions involved in the biosynthesis of histidine; one of the nine enzymes is bifunctional (LOPER, GRABNAR, STAHL, HARTMAN and HARTMAN 1964). The histidine operon is contained in a linear segment of deoxyribonucleic acid (DNA) estimated by AMES, GOL...

Hypermutation in derepressed operons of Escherichia coli K12.

This article presents evidence that starvation for leucine in an Escherichia coli auxotroph triggers metabolic activities that specifically target the leu operon for derepression, increased rates of transcription, and mutation. Derepression of the leu operon was a prerequisite for its activation by the signal nucleotide, guanosine tetraphosphate, which accumulates in response to nutritional str...

Characterization of the cyn operon in Escherichia coli K12.

Escherichia coli can overcome the toxicity of environmental cyanate by hydrolysis of cyanate to ammonia and bicarbonate. This reaction is catalyzed by the enzyme cyanase, encoded by the cynS gene. The nucleotide sequence of cynS has been reported (Sung, Y.-c., Anderson, P. M., and Fuchs, J. A. (1987) J. Bacteriol. 169, 5224-5230). The nucleotide sequence of the complete cyn operon has now been ...

Directed evolution of cellobiose utilization in Escherichia coli K12.

The cellobiose catabolic system of Escherichia coli K12 is being used to study the role of cryptic genes in evolution of new functions. Escherichia coli does not use beta-glucoside sugars; however, mutations in several loci can activate the cryptic bgl operon and permit growth on the beta-glucoside sugars arbutin and salicin. Such Bgl+ mutants do not use cellobiose, which is the most common bet...

Plasmid-instability in acrA mutants of Escherichia coli K12.