Phenotypic and transcriptomic characterization of ElyC-defective Escherichia coli cells reveal the importance of ElyC in cell envelope biosynthesis at optimal and sub-optimal temperatures

ABSTRACT: The bacterial cell envelope is the frontier line of the adaptational defense that protects cells against environmental and intrinsic stressors to maintain homeostasis. Deciphering the molecular pathways involved in envelope biology is of high importance for both fundamental sciences and translational applications. Peptidoglycan (PG) is one of the main structural components of bacterial cell envelopes. It protects bacteria against mechanical and osmotic stress, confers cell shape and physical integrity. In a previous study, we identified that the Escherichia coli ElyC protein containing a highly conserved domain of an unknown function is required for envelope integrity at low temperature. ElyC was shown to be essential for PG assembly at room temperature (21°C) and to be involved in the metabolism of the lipid carrier necessary for the membrane step of the biosynthesis pathways for PG and other bacterial envelope polysaccharides. PG assembly was completely blocked in ElyC-defective cells grown at 21°C, leading to a terminal phenotype of cell lysis. The physiological importance of ElyC in bacterial cells grown at the physiological temperature of 37°C had not yet been investigated. To study this, we performed phenotypic characterization and transcriptomic profiling of ElyC-defective E. coli cells were grown at 37°C and 21°C, compared to wild-type cells. Even if ∆elyC mutant cells grow as well as wild-type cells at 37°C, microscopic analysis revealed that cellular morphology is altered by the lack of ElyC at this temperature. PG quantification and analysis confirmed that PG biosynthesis is significantly inhibited in the absence of ElyC at 37°C. We further have shown that ∆elyC mutant cells are more sensitive to PG-targeting β-lactam antibiotics than wild-type cells at 37°C. The RNA-Seq transcriptomic study showed that elimination of the ElyC evokes a highly defective cellular envelope when elyC mutant grows at 21°C, whereas at 37°C, the absence of ElyC leads to a moderate cellular response. While the PG defect of cells inactivated for ElyC is lethal at 21°C, ElyC-defective cells maintain enough PG integrity to grow and survive at 37°C. However, those cells are morphologically defective, are coping with envelope stress and are more sensitive to PG-targeting antibiotics. Overall, our data support a crucial role for ElyC in the metabolic flux for the PG biosynthesis pathway at optimal and suboptimal temperatures.

ORGANISM(S): Escherichia coli

PROVIDER: GSE141694 | GEO | 2020/03/20

REPOSITORIES: GEO