title: Cloning of a Neisseria meningitidis gene for L-lactate dehydrogenase (L-LDH): evidence for a second meningococcal L-LDH with different regulation.
abstract: We report the cloning of lldA, a Neisseria meningitidis gene for L-lactate dehydrogenase (L-LDH). Escherichia coli contains a single L-LDH gene (lldD) in the lld operon (previously lct). E. coli grown in complex media does not have L-LDH activity, but the activity is induced by growth in defined medium with L-lactate as the carbon source. In contrast, meningococci contain at least one L-LDH in addition to the lldA gene product. These enzymes are active in meningococci grown in complex media and are not dependent on growth in L-lactate. The predicted amino acid sequence of lldA is homologous to that of E. coli lldD and of other prokaryotic and eukaryotic flavin mononucleotide-containing enzymes that catalyze the oxidation of L-lactate and other small alpha-hydroxy acids. A mutant with a deletion in lldA was found to have reduced L-LDH activity. However, this mutant was able to grow on L-lactate, indicating that a second L-LDH must exist. Activity of the lldA enzyme was affected by growth conditions, being increased by growth on a defined medium with either L-lactate or pyruvate as the carbon source. For meningococci grown on a complex medium, activity of the lldA enzyme was increased by growth on plates or in well-aerated broth. A second L-lactate-oxidizing activity was seen in bacteria grown in poorly aerated broth. Neisseria gonorrhoeae contains a homolog of lldA. As for meningococci, mutation of the gonococcal lldA reduced L-LDH activity but did not affect growth on L-lactate.
authors: Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, New York 10021, USA.
authors: A L
authors: AL
authors: Erwin
authors: E C
authors: EC
authors: Gotschlich
mesh_terms: D000332:Aerobiosis; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017931:DNA Primers; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics; D007527:Isoenzymes; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D009876:Operon; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase