Effects of glnL and other regulatory loci on regulation of transcription of glnA-lacZ fusions in Klebsiella aerogenes.

Mutants of Klebsiella aerogenes containing genetic fusions of glnA to lacZ were isolated by using Mu dl (lac, bla) bacteriophage and a Mu Kmr helper phage with the host range of bacteriophage P1. Synthesis of beta-galactosidase in these strains is regulated in response to nitrogen metabolites and regulatory gln loci and is rendered constitutive by a mutation in the linked glnL gene. Complementation studies indicated that glnL is a separate locus from glnA and glnG and that insertions in glnA are partially polar on glnL expression. These results support the hypothesis that glnA, glnL, and glnG are organized in an operon with multiple promoters.