Primary structural relationships may reflect similar DNA replication strategies.

The primary structures of several proteins of bacterial and viral origin involved in the initiation of DNA synthesis and its subsequent elongation were compared. It was found that the known sequences of DNA polymerases and the single-stranded DNA binding proteins from phage T7 and Escherichia coli aligned well. Furthermore, segmental homologies were found in the phage phi 29 and adenovirus polymerases as well as in their DNA binding proteins. These results suggest similar mechanisms of DNA synthesis for E. coli and T7 on the one hand and for phi 29 and adenovirus on the other.