DNA Replication and Proteins That Bind to DNA

Cells of Escherichia coli 15T^- were exposed to nalidixic acid or starved for thymine to inhibit DNA synthesis while protein synthesis was allowed to continue. These treatments are known to allow subsequent DNA synthesis to continue for many hours in the absence of protein synthesis. The proteins extracted from these cells that bind to DNA were examined by DNA-cellulose chromatography and disc-gel electrophoresis. One or two species were found to be absent, or to be present in greatly reduced amounts, under these conditions.