Abstract
Mutation in the gene lon (capR) of Escherichia coli K-12 causes conditional inhibition of cell division. Two-dimensional gel electrophoresis was used to compare polypeptides from isogenic capR+ and capR strains. One polypeptide was present in the capR strain but absent in the wild-type strain, and it was proteolyzed when the pure capR+ protease was added to the capR extract. This polypeptide could only be detected in the capR strain when cell division was inhibited, and its synthesis was independent of the SOS response.