Three overlapping lct genes involved in L-lactate utilization by Escherichia coli

作者：Jiaojiao Dong, J S Taylor, David J. Latour, Shiro Iuchi, E. C. C. Lin · 发表于：Journal of Bacteriology · 年份：1993 · DOI：10.1128/jb.175.20.6671-6678.1993 · 被引用次数：132 · 研究领域：Bacterial Genetics and Biotechnology、Microbial Metabolic Engineering and Bioproduction、Amino Acid Enzymes and Metabolism

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.