Abstract
The Escherichia coli dnaB252 allele is the only dnaB mutation which confers a DNA initiation-defective phenotype on the cell. The presence of a multicopy hybrid plasmid containing the dnaC+ gene in a dnaB252 strain completely suppressed the temperature-sensitive phenotype. At high temperature, the dnaB252 protein evidently has a lowered affinity for dnaC protein. The formation of a dnaB-dnaC complex is apparently mandatory for initiation.