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J. Bacteriol., Aug 1996, 4807-4813, Vol 178, No. 16
AL Erwin and EC Gotschlich
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.
Copyright © 1996, American Society for Microbiology
Cloning of a Neisseria meningitidis gene for L-lactate dehydrogenase (L- LDH): evidence for a second meningococcal L-LDH with different regulation
Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, New York 10021, USA.
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