Expression of the hut operons of Salmonella typhimurium in Klebsiella aerogenes and in Escherichia coli.

The normal hut (histidine utilization) operons, as well as those with mutations affecting the regulation of their expression, of Salmonella typhimurium were introduced on an F' episome into cells of S. typhimurium and Klebsiella aerogenes whose chromosomal hut genes had been deleted and into cells of Escherichia coli, whose chromosome does not carry hut genes. The episomal hut operons respond in a manner very similar to induction and catabolite repression in all three organisms. The small differences found reflect both different abilities to take up inducers from the medium and different degrees of catabolite repression exerted by glucose.