Knockout of the two ldh genes has a major impact on peptidoglycan precursor synthesis in Lactobacillus plantarum.
Most bacteria synthesize muramyl-pentapeptide peptidoglycan precursors ending with a D-alanyl residue (e.g., UDP-N-acetylmuramyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala). However, it was recently demonstrated that other types of precursors, notably D-lactate-ending molecules, could be synthesized by several lactic acid bacteria. This particular feature leads to vancomycin resistance. Vancomycin is a glycopeptide antibiotic that blocks cell wall synthesis by the formation of a complex with the extremity of peptidoglycan precursors. Substitution of the terminal D-alanine by D-lactate reduces the affinity of the antibiotic for its target. Lactobacillus plantarum is a lactic acid bacterium naturally resistant to vancomycin. It converts most of the glycolytic pyruvate to L- and D-lactate by using stereospecific enzymes designated L- and D-lactate dehydrogenases, respectively. In the present study, we show that L. plantarum actually synthesizes D-lactate-ending peptidoglycan precursors. We also report the construction of a strain which is deficient for both D- and L-lactate dehydrogenase activities and which produces only trace amounts of D- and L-lactate. As a consequence, the peptidoglycan synthesis pathway is drastically affected. The wild-type precursor is still present, but a new type of D-alanine-ending precursor is also synthesized in large quantities, which results in a highly enhanced sensitivity to vancomycin.
Ferain
T
T
Laboratoire de Génétique Moléculaire, Université Catholique de Louvain, Belgium.
Hobbs
J N
JN
Richardson
J
J
Bernard
N
N
Garmyn
D
D
Hols
P
P
Allen
N E
NE
Delcour
J
J
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D004352:Drug Resistance, Microbial; D005798:Genes, Bacterial; D006020:Glycopeptides / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D007778:Lactobacillus / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D016296:Mutagenesis; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000737:chemistry; D017334:Teicoplanin / Q000494:pharmacology; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000031:analogs & derivatives; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D010457:Peptidoglycan; D014538:Uridine Diphosphate N-Acetylmuramic Acid; D019344:Lactic Acid; D017334:Teicoplanin; D014640:Vancomycin; D007770:L-Lactate Dehydrogenase