ISOLATION AND CHARACTERIZATION OF AUTOLYSIS-DEFECTIVE MUTANTS OF ESCHERICHIA-COLI THAT ARE RESISTANT TO THE LYTIC ACTIVITY OF SEMINALPLASMIN

Two temperature-sensitive autolysis-defective mutants of Escherichia coli were isolated and shown to be reistant to lysis induced by seminalplasmin, an antimicrobial protein from bovine seminal plasma, as well as to lysis induced by ampicillin, D-cycloserine and nocardicin, at 37 or 42°C but not at 30°C. The mutants were, however, sensitive to inhibition of RNA synthesis by seminalplasmin even at the nonpermissive temperature. Temperature-resistant revertants of the mutants were sensitive to lysis induced by the various antibiotics at 37 or 42°C. The mutations in both strains were mapped at 58 min on the E. coli linkage map. The lysis resistance of the mutants was phenotypically suppressed by the addition of NaCl. Partial suppression of the lysis-resistant phenotype was also observed in a relA genetic background.