title: Construction of a single-copy integration vector and its use in analysis of regulation of the trp operon of Bacillus subtilis.
abstract: A single-copy integration vector was used for the in vitro construction of translational fusions to the lacZ gene of Escherichia coli. Insertion of a single copy of the lacZ fusion into the B. subtilis chromosome leads to an easily detected Amy- phenotype. A trpE-lacZ fusion was constructed in which the trp promoter directs hybrid beta-galactosidase (beta Gal) synthesis. The level of beta Gal in a wild-type strain carrying the trpE-lacZ fusion in the chromosome is regulated by exogenous tryptophan, while a 5-methyltryptophan-resistant mutant constitutively synthesizes betaGal. A trpF-lacZ fusion was constructed and used to determine the effect of a frameshift mutation in the trpE gene on expression of the trpF-lacZ fusion. The frameshift mutation in trpE led to a three-fold reduction in the levels of the trpF-lacZ fusion. The levels of the betaGal activity of these integrated lacZ fusions appear to provide a quantitative measure of the expression of B. subtilis genes under single-copy conditions.
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000235:genetics*; D005696:Galactosidases / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D005809:Genes, Regulator; D005822:Genetic Vectors; D005838:Genotype; D009876:Operon; D010957:Plasmids; D014176:Protein Biosynthesis; D014161:Transduction, Genetic; D014364:Tryptophan / Q000378:metabolism*; D001616:beta-Galactosidase / Q000235:genetics*
chemical_list: D014364:Tryptophan; D004262:DNA Restriction Enzymes; D005696:Galactosidases; D001616:beta-Galactosidase