INTERACTION OF P1 REPA WITH REPLICATION ORIGIN PLASMID RTS1 - CAPABILITY OF AN INITIATOR PROTEIN INDUCING REPLICATION FROM A FOREIGN ORIGIN

Rst1 RepA and Pi RepA are trans-acting proteins essential for the init iation of replication of plasmid Rts1 and prophage P1, respectively. I n this study, we found that, in vitro P1 RepA bound to the Rts1 ori fr agment and Rts1 incI fragment as strongly as Rts1 RepA. In addition P1 RepA, in trans, activated the Rts1 replication origin that was cloned in pBR322, thus allowing the ori plasmid to be maintained in a polA E . coil host. Under these conditions, however, the ori plasmid was unst able as compared with that when activated by Rts1 RepA. In addition, w e found that Rts1 RepA showed no interaction with the P1 replication o rigin. (C) 1997 Academic Press.