Antisense RNA Knockdown and Genomic Deletion of wecD Sensitizes Escherichia coli to Bacteriophage T7 Infection

WecD is an essential enzyme in the biosynthesis of enterobacterial common antigen (ECA), an outer membrane glycophospholipid that is conserved among all members of the Enterobacteriaceae family, including Escherichia coli. Mutations of wecD disrupt ECA biosynthesis and result in a hypervesiculation phenotype characterized by increased production of outer membrane vesicles (OMVs). OMVs have been shown to occur during the onset of bacteriophage adhesions to host cells, which is a proposed mechanism of bacterial avoidance of phage infections. In this study, we investigated whether silencing WecD expression increased resistance to bacteriophage T7 in E. coli by (1) silencing wecD expression using antisense technology and (2) genomic deletion of wecD from the Keio strain collection. Counter to our hypothesis, both wecD asRNA knockdown and wecD genomic deletion appeared to sensitize E. coli to bacteriophage T7 infection. Additionally, and in line with our expectation that genomic deletion is a more effective means of mitigating gene expression as compared to using an asRNA knockdown, wecD genomic deletion was observed to increase E. coli sensitivity to bacteriophage T7 infection to a greater extent than wecD asRNA knockdown. Based on our observations, we propose that the presence of antibiotics and the silencing of wecD may induce cellular and membrane stress in the OM and compromise the physical protection of the mutant cells to bacteriophage T7 infection, therefore contributing to this increased sensitization to phage infections observed in wecD-silenced cells.