DNA sequence of an amber replication mutant indicates that a 29 kd protein is the product of the F plasmid replication gene.

DNA sequencing shows that the mutational alteration resulting from an amber-suppressible replication-defective mutation of F plasmid is a single base pair change from C:G to T:A which yields an amber codon in the coding frame for a 29 kd polypeptide located in the minimal replication region. We thus identified the gene indispensable for F DNA replication as the coding frame which encodes a 29 kd polypeptide. We will designate this gene repA.