DOI: 10.1128/jb.00496-26 ISSN: 0021-9193
Peptidoglycan remodeling prevents antibiotic resistance during oxidative stress
Jonathan Sukadi Miala, Léanne Arcand-Carrier, Rosalie Lapointe, Claire Morin, Charles Sasseville, David Lalaouna, Eric Massé ABSTRACT
The bacterial small RNA (sRNA) OxyS is expressed in
Escherichia coli
during oxidative stress. The sRNA OxyS enhances cell survival by controlling genes involved in the regulation of hydrogen peroxide (H
2
O
2
) and iron-sulfur (Fe-S) cluster formation. Here, we used the MS2 affinity purification coupled with RNA sequencing (MAPS) technique to identify new target mRNAs of the sRNA OxyS. Our analysis revealed a significant enrichment of
mepS
mRNA, which encodes a peptidoglycan endopeptidase that promotes cell growth. Our results confirm a previous report on the sRNA OxyS repressing the translation of
mepS
. We also found that an Δ
oxyS
background facilitates the emergence of mutations, conferring increased resistance to the last-resort antibiotics polymyxin B and E (colistin), but only in the presence of the target
mepS
gene. This suggests that the translation repression of
mepS
by OxyS could prevent mutations in bacterial DNA during H
2
O
2
-induced oxidative stress. Moreover, we show that adding the antioxidant thiourea or sequestering iron in the Δ
oxyS
background effectively reduces the emergence of resistance against both polymyxin B and colistin. These results suggest that reactive oxygen species (ROS), in conjunction with intracellular iron, play a key role in driving the emergence of antibiotic resistance. Overall, our work underlines a mechanism of antimicrobial emergence implicating oxidative stress, intracellular Fe, and cell wall remodeling in
E. coli
.
IMPORTANCE
This study uncovers an underexplored link between peptidoglycan remodeling and oxidative stress responses during exposure to antibiotics. By elucidating how MepS and the sRNA OxyS interact in the presence of polymyxins and oxidative stress, our study suggests that MepS may exert an anti-mutator function. The repression of
mepS
translation by OxyS seems to limit the emergence of antibiotic resistance driven by DNA mutations. Together, these findings suggest cell wall remodeling and oxidative stress response pathways as promising targets to enhance antibiotic efficacy and limit the emergence of resistance.