Effect of chemical modification by (di)imidoesters on cells and cell envelope components of Escherichia coli and Salmonella typhimurium.

Cells and cell envelope components of Escherichia coli and Salmonella typhimurium were treated with mono- and bifunctional imidates like methylbutyrimidate, methyl-4-mercaptobutyrimidate and dimethylsuberimidate, and after determination of the appropriate conditions, the effects on structure and function were investigated. Within 10 min after treatment of the bacteria with 5 mM of the (di)imidoesters, active transport, DNA-, RNA-, protein- and lipid-synthesis were severely inhibited. After crosslinking, cell envelope components, e.g. phospholipids, lipopolysaccharide, and periplasmic proteins, became partly inextractable. Crosslinked cells showed increased resistance to ultrasonic treatment and osmotic or detergent induced lysis. By the reaction of (di)imidoesters with phospholipids containing no amino groups, it could be demonstrated that non-amidine products were also formed. In addition, freeze-fracturing and freeze-etching demonstrated distinct crosslinked areas in the cell envelope of E. coli B.