LptD depletion disrupts morphological homeostasis and upregulates carbohydrate metabolism in <i>Escherichia coli</i>

Abstract In a previous in silico study, we identified an essential outer membrane (OM) protein (LptD) as attractive target for development of novel antibiotics. Here, characterised the effects LptD depletion on Escherichia coli physiology and morphology. An E. CRISPR interference (CRISPRi) strain was constructed to allow control lptD expression. Induction CRISPRi system led ∼440-fold reduction gene Dose-dependent growth inhibition observed, where strong knockdown effectively inhibited initial but partial exhibited maximum overall killing after 24 h. morphological changes cells long, filamentous cell shapes cytoplasmic accumulation lipopolysaccharide (LPS). Transcriptional profiling by RNA-Seq showed that upregulation carbohydrate metabolism, especially colanic acid biosynthesis pathway. This pathway further overexpressed presence sublethal concentrations colistin, antibiotic targeting LPS, indicating specific transcriptional response this synergistic envelope damage. Additionally, exposure colistin during resulted downregulation pathways related motility chemotaxis, two important virulence traits. Altogether, these results show i) affects survival, ii) upregulates iii) synergizes with antimicrobial activity colistin.