Induction of autolysis in starved Escherichia coli cells by seminalplasmin, an antimicrobial protein from bovine seminal plasma

A pair of relA + and relA E. coli strains, otherwise isogenic, were studied with regard to the susceptibility of starved cells to lysis induced by the natural peptide seminalplasmin. Starved relA cells were more sensitive to seminalplasmin‐induced lysis when compared to starved relA + cells. Nevertheless, pronounced lysis of starved relA + cells was observed with increase in the concentration of seminalplasmin. In conctrast, ampicillin could not lyse starved relA + cells even at very high concentrations. Further, seminalplasmin could cause loss of viability and degradation of peptidoglycan in starved relA + cells. These observations suggest that, unlike many other antibiotics, seminalplasmin can induce autolysis under the conditions of a stringent response.