LptDOX levels are decreased by secA and secB suppressor mutations. ΔlptE strains carrying plasmid plptE+ with secA+
secB+ (JY105), with secA827::IS1 secB+ (JY106), or with secA+ ΔsecB::kan (MG949) and ΔlptE strains carrying plptE14 with secA+
secB+ (JY107), with secA827::IS1 secB+ (JY108), or with secA+ ΔsecB::kan (MG950) were grown to stationary phase, and protein samples were prepared under reducing (LptE) or nonreducing (LptDOX) conditions and immunoblotted with anti-LptE or anti-LptD antisera.