title: Insertion proQ220::Tn5 alters regulation of proline porter II, a transporter of proline and glycine betaine in Escherichia coli.
abstract: Mutation pro-220::Tn5, which increases the resistance of Escherichia coli to 3,4-dehydroproline (M. E. Stalmach, S. Grothe, and J. M. Wood, J. Bacteriol. 156:481-486, 1983), is not linked to putP, proP, or proU. It was located at 40.4 min on the E. coli chromosomal linkage map, by conjugational and transductional mapping, and is now denoted proQ220::Tn5. Proline porter II was not detectable when proQ220::Tn5 proP+ bacteria were cultivated under optimal conditions or with nutritional stress (amino acid limitation). Toxic proline analog sensitivity and proline porter II activity were partially restored to proQ220::Tn5 proP+ bacteria, but not to a proQ220::Tn5 proP219 strain, by a hyperosmotic shift and by growth under osmotic stress. Elevated expression of a proP::lacZ gene fusion, for bacteria grown under osmotic stress, was not influenced by the proQ220::Tn5 insertion. We propose that the proQ locus encodes a positive regulatory element which elevates proline porter II activity.
authors.affiliation: Department of Chemistry and Biochemistry, University of Guelph, Ontario, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Milner
authors.forename: J M
authors.initials: JM
authors.lastname: Wood
mesh_terms: D000483:Alleles; D026921:Amino Acid Transport Systems, Neutral; D001622:Betaine / Q000378:metabolism*; D001692:Biological Transport; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D005796:Genes; D005798:Genes, Bacterial; D005838:Genotype; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D011392:Proline / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D004251:DNA Transposable Elements; D026901:Membrane Transport Proteins; D001622:Betaine; C033082:proline transporter; D011392:Proline