Replication of the broad host range plasmid RSF1010 in cell-free extracts of Escherichia coli and Pseudomonas aeruginosa.

Replication of exogenous RSF1010 DNA can be carried out by soluble enzyme systems from Escherichia coli and Pseudomonas aeruginosa. It requires the function of RSF1010-encoded replication protein(s), which is not expressed in extracts from plasmid-free bacteria. In contrast to previously described in vitro systems for plasmid replication, initiation of RSF1010 DNA synthesis is independent of transcription catalyzed by host RNA polymerase. This is indicated by the insensitivity of RSF1010 replication to rifampicin as well as to RNA polymerase antibodies. It is proposed that a host RNA polymerase transcription-independent initiation mechanism might be a general property of broad host range plasmids.