title: Three overlapping lct genes involved in L-lactate utilization by Escherichia coli.
abstract: In Escherichia coli, the lct locus at min 80 on the chromosome map is associated with ability to grow on L-lactate and to synthesize a substrate-inducible flavin-linked dehydrogenase. Similar to that of the glpD-encoded aerobic glycerol-3-phosphate dehydrogenase, the level of induced enzyme activity is elevated by aerobiosis. Both of these controls are mediated by the two-component signal transduction system ArcB/ArcA, although sensitivity to the control is much more striking for L-lactate dehydrogenase. This study disclosed that the lct locus contained three overlapping genes in the clockwise order of lctD (encoding a flavin mononucleotide-dependent dehydrogenase), lctR (encoding a putative regulator), and lctP (encoding a permease) on the chromosomal map. These genes, however, are transcribed in the counterclockwise direction. No homology in amino acid sequence was found between aerobic glycerol-3-phosphate dehydrogenase and L-lactate dehydrogenase. A phi (lctD-lac) mutant was inducible by L-lactate but not D-lactate. Although the mutant lost the ability to grow on L-lactate, growth on D-lactate, known to depend on a different enzyme, remained normal.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: J M
authors.initials: JM
authors.lastname: Dong
authors.forename: J S
authors.initials: JS
authors.lastname: Taylor
authors.forename: D J
authors.initials: DJ
authors.lastname: Latour
authors.forename: S
authors.initials: S
authors.lastname: Iuchi
authors.forename: E C
authors.initials: EC
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005420:Flavoproteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D005807:Genes, Overlapping; D005809:Genes, Regulator; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D007773:Lactates / Q000378:metabolism* / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D016415:Sequence Alignment; D014157:Transcription Factors; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D005420:Flavoproteins; D007773:Lactates; C083722:LldP protein, E coli; C083721:LldR protein, E coli; D026901:Membrane Transport Proteins; D014157:Transcription Factors; D007770:L-Lactate Dehydrogenase; C083720:lldD protein, E coli