A genetic suppressor of an E. coli mutant lacking five lytic transglycosylases

The peptidoglycan (PG) cell wall is a mesh-like layer that shapes bacteria and protects against turgor. PG hydrolases cleave linkages in PG, and mutants lacking various combinations of PG hydrolases grow as misshapen cells. A genetic suppressor that reverses the shape defect of an Escherichia coli mutant lacking five lytic transglycosylases, which cleave the PG glycan backbone, was obtained and sequenced on an Oxford Nanopore MinION device. Filtered reads were mapped against the E. coli MG1655 reference genome, which revealed a 21 kb deletion in the suppressing (MAJ1075) but not parent (MAJ718) strain. Findings from these studies were used to deepen our understanding of PG maturation in E. coli.