Lactobacillus plantarum ldhL gene: overexpression and deletion.
Lactobacillus plantarum is a lactic acid bacterium that converts pyruvate to L-(+)- and D-(-)-lactate with stereospecific enzymes designated L-(+)- and D-(-)-lactate dehydrogenase (LDH), respectively. A gene (designated ldhL) that encodes L-(+)-lactate dehydrogenase from L. plantarum DG301 was cloned by complementation in Escherichia coli. The nucleotide sequence of the ldhL gene predicted a protein of 320 amino acids closely related to that of Lactobacillus pentosus. A multicopy plasmid bearing the ldhL gene without modification of its expression signals was introduced in L. plantarum. L-LDH activity was increased up to 13-fold through this gene dosage effect. However, this change had hardly any effect on the production of L-(+)- and D-(-)-lactate. A stable chromosomal deletion in the ldhL gene was then constructed in L. plantarum by a two-step homologous recombination process. Inactivation of the gene resulted in the absence of L-LDH activity and in exclusive production of the D isomer of lactate. However, the global concentration of lactate in the culture supernatant remained unchanged.
Ferain
T
T
Laboratoire de Génétique Moléculaire, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
Garmyn
D
D
Bernard
N
N
Hols
P
P
Delcour
J
J
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D015870:Gene Expression; D005798:Genes, Bacterial; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D007778:Lactobacillus / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics; D017384:Sequence Deletion
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D007770:L-Lactate Dehydrogenase