Membrane protein shedding, Effect

A corollary question that arises is what effect does interference of peptidoglycan synthesis have on the outer membrane In DAP auxotrophs of E. coli, we observed an extensive overproduction of surface material under conditions of limited supply of DAP. This effect appears to be analogous to that observed with a DAP-decarboxylase mutant which excretes large amounts of predominantly LPS under conditions of lysine limitation. The excretion of surface material was also observed when protein synthesis was blocked, and when it was not restricted to mutant strains only, but occurred in all of the E. coli strains tested/ In addition to LPS, which accounted for 50% of the excreted material, the cells also released phospholipids (35%) and protein (15%). It is interesting that these authors also found some shedding of the LPS-lipid-protein complex into the medium under normal conditions of growth. These observations may be related to the occasional bleb formation and detachment we had seen in earlier work on the structure of unfixed cell walls of E. coli. ... 

---