Mechanism of protein priming DNA replication of B.subtilis phage M2.

: B.subtilis phage M2 uses a protein, instead of RNA, as the primer of its DNA replication. Hence this protein encoded in the phage genome is called as the primer protein (PP). At the initiation of DNA replication, a hetero dimer complex with its own DNA polymerase and the PP supposed to interact with the terminal protein (TP), which is covalently bound to the template DNA (TP-DNA). PP contained an important adhesive amino acid sequence, Arg-Gly-Asp (RGD), near the carboxyl terminal. We have recently showed that the synthetic RGD peptide inhibited the transfection of phage M2. By site-directed mutagenesis, we introduced different amino acid into the RGD site of PP. These altered PP decreased obviously the priming activity in vitro.