isopropyl-thiogalactoside and 2-methylglutamic-acid

The gltS gene is known to encode a sodium-dependent, glutamate-specific permease. We have localized the Escherichia coli K12 gltS gene with respect to the spoT gene, sequenced it, and recombined a null insertion-deletion allele into the chromosome without loss of viability. The gltS null allele gives a Glt- phenotype, i.e. it abolishes the ability of a gltCc host to grow on glutamate as sole carbon and nitrogen source and also confers alpha-methylglutamate resistance. A multicopy plasmid expressing the gltS gene can reverse the Glt- phenotype of gltS- or wild-type strains while other plasmids show host-dependent complementation patterns. Induction of gltS gene overexpression under control of isopropyl-beta-D-thiogalactoside (IPTG)-inducible promoters severely inhibits growth. The GltS protein is deduced to be a 42425 dalton hydrophobic protein with 2 sets of 5 possible integral protein domains, each flanking a central hydrophilic, flexible region.

Topics: Alleles; Amino Acid Sequence; Amino Acid Transport Systems, Acidic; Base Sequence; DNA, Bacterial; Escherichia coli; Escherichia coli Proteins; Frameshift Mutation; Genes, Bacterial; Genetic Complementation Test; Genetic Linkage; Glutamates; Isopropyl Thiogalactoside; Membrane Transport Proteins; Molecular Sequence Data; Open Reading Frames; Phenotype; Plasmids; Polymerase Chain Reaction; Promoter Regions, Genetic; Restriction Mapping; Symporters