Functional and morphological adaptation to peptidoglycan precursor alteration in Lactococcus lactis.
Cell wall peptidoglycan assembly is a tightly regulated process requiring the combined action of multienzyme complexes. In this study we provide direct evidence showing that substrate transformations occurring at the different stages of this process play a crucial role in the spatial and temporal coordination of the cell wall synthesis machinery. Peptidoglycan substrate alteration was investigated in the Gram-positive bacterium Lactococcus lactis by substituting the peptidoglycan precursor biosynthesis genes of this bacterium for those of the vancomycin-resistant bacterium Lactobacillus plantarum. A set of L. lactis mutant strains in which the normal d-Ala-ended precursors were partially or totally replaced by d-Lac-ended precursors was generated. Incorporation of the altered precursor into the cell wall induced morphological changes arising from a defect in cell elongation and cell separation. Structural analysis of the muropeptides confirmed that the activity of multiple enzymes involved in peptidoglycan synthesis was altered. Optimization of this altered pathway was necessary to increase the level of vancomycin resistance conferred by the utilization of d-Lac-ended peptidoglycan precursors in the mutant strains. The implications of these findings on the control of bacterial cell morphogenesis and the mechanisms of vancomycin resistance are discussed.
Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
Marie
M
Deghorain
Laetitia
L
Fontaine
Blandine
B
David
Jean-Luc
JL
Mainardi
Pascal
P
Courtin
Richard
R
Daniel
Jeff
J
Errington
Alexei
A
Sorokin
Alexander
A
Bolotin
Marie-Pierre
MP
Chapot-Chartier
Bernard
B
Hallet
Pascal
P
Hols
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D049109:Cell Proliferation; D002473:Cell Wall / Q000378:metabolism*; D004352:Drug Resistance, Microbial; D016678:Genome; D019344:Lactic Acid / Q000737:chemistry; D013294:Lactococcus lactis / Q000378:metabolism*; D008712:Methicillin / Q000737:chemistry; D008954:Models, Biological; D009154:Mutation; D046915:Penicillin-Binding Proteins / Q000378:metabolism; D010457:Peptidoglycan / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D019344:Lactic Acid; D014640:Vancomycin; D008712:Methicillin