Two types of temperature sensitivity in DNA replication of an Escherichia coli dnaB mutant

Abstract

In the Escherichia coli dnaB mutant BT165/70 were observed two types of temperature sensitivity of DNA replication: one slow but irreversible, occurring before the initiation of DNA replication, and the other instant but reversible, occurring during replication. These two types of temperature sensitivity appear to result from the single dnaB mutation. The observation suggests two different states of the dnaB gene product within the cell. Interaction of the dnaB protein with other components of the hypothetical replication complex is suggested. A temperature-insensitive revertant (second site mutation) of BT165/70 was isolated whose phenotype suggests an alteration in the interacting ability of the revertant protein.