Aspartate deficiency limits peptidoglycan synthesis and sensitizes cells to antibiotics targeting cell wall synthesis in Bacillus subtilis

Abstract

Peptidoglycan synthesis is an important target for antibiotics and relies on intermediates derived from central metabolism. As a result, alterations of metabolism may affect antibiotic sensitivity. An aspB mutant is auxotrophic for aspartate (Asp) and asparagine (Asn) and lyses when grown in Difco sporulation medium (DSM), but not in LB medium. Genetic and physiological studies, supported by amino acid analysis, reveal that cell lysis in DSM results from Asp limitation due to a relatively low Asp and high glutamate (Glu) concentrations, with Glu functioning as a competitive inhibitor of Asp uptake by the major Glu/Asp transporter GltT. Lysis can be specifically suppressed by supplementation with 2,6-diaminopimelate (DAP), which is imported by two different cystine uptake systems. These studies suggest that aspartate limitation depletes the peptidoglycan precursor meso-2,6-diaminopimelate (mDAP), inhibits peptidoglycan synthesis, upregulates the cell envelope stress response mediated by σ and eventually leads to cell lysis. Aspartate limitation sensitizes cells to antibiotics targeting late steps of PG synthesis, but not steps prior to the addition of mDAP into the pentapeptide sidechain. This work highlights the ability of perturbations of central metabolism to sensitize cells to peptidoglycan synthesis inhibitors.

Deciphering the essentiality and function of the anti‐σM factors in Bacillus subtilis

“…Luciferase reporter construction and measurement was performed as previous described (Zhao et al , ). The luciferase reporters were constructed by inserting the tested promoters into the multicloning sites of pBS3C lux (Radeck et al , ).…”

Identification of the first glyphosate transporter by genomic adaptation

“…3A). The gltT and gltP genes code for the high-affinity sodium-coupled glutamate/aspartate symporter GltT and for the low-affinity proton/glutamate symporter GltP respectively (Tolner et al, 1995;Zaprasis et al, 2015;Zhao et al, 2018). 2B).…”

“…de) (Michna et al, 2014). The gltT and gltP genes code for the high-affinity sodium-coupled glutamate/aspartate symporter GltT and for the low-affinity proton/glutamate symporter GltP respectively (Tolner et al, 1995;Zaprasis et al, 2015;Zhao et al, 2018). The fact that all strains had acquired mutations in genes encoding transporters that are involved in glutamate and aspartate uptake suggests that the proteins also transport glyphosate (Fig.…”

Lysis of a Lactococcus lactis Dipeptidase Mutant and Rescue by Mutation in the Pleiotropic Regulator CodY

“…Indeed, depletion of D-Asp in the PG cross bridge in L. lactis affects cell integrity, resulting in cell shape defects. A shortage of aspartate, the source of the third amino acid of the pentapeptide, mDAP, limits PG synthesis in Bacillus subtilis (32,33).…”