Figure 4. Mutations to ompA and rfa genes exhibit sign epistasis.
A) Cell envelope stiffness for ΔompA mutants from three wild-type backgrounds, and for the deletion of the periplasmic domain (ΔompAPD) of OmpA in the MG1655 background. B) Outer membrane stiffness for the ΔompA and ΔompAPD mutants. C) A ΔompA cell before and after 400 mM hyperosmotic shock. D) Percentage of cells that developed outer membrane bulges after 400 mM hyperosmotic shocks. E) Cell envelope stiffness versus core oligosaccharide length for mutants in a ΔompA background, normalized by wild-type cell-envelope stiffness. F) Outer membrane stiffness for ΔompA and ΔompA ΔrfaJ mutants.