Mutants of Escherichia coli hypersensitive to an antitumor protein: Neocarzinostatin.

Abstract

A mutant of E. coli (MP2) sensitive to an antitumor antibiotic of high molecular weight and to proteinase was isolated and its characteristics were studied. The sensitivity of mutant MP2 to neocarzinostatin was greatly influenced by the environment in which MP2 was exposed to NCS. MP2 was also sensitive to a certain extent to some hydrolytic enzymes added exogenously such as pronase, DNase, and RNase. The sensitivity of the parental spheroplast to NCS and pronase was still lower than that of intact MP2. Proteinase-induced inactivation of ornithine transcarbamylase of the intact cells occurred only with MP2, but it did not with the parental cells, while it occurred with the spheroplasts of both strains. From the analysis of membrane proteins by polyacrylamide gel electrophoresis, MP2 seemed to have a considerable change in the outer and inner membranes. The mutations responsible for these characters located in two separate regions of chromosome; i.e., one near his locus and the other between the point of origin of Hfr AB312 and the marker lys.