Rifampicin-resistant initiation of DNA synthesis on the isolated strands of ColE plasmid DNA. |
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| Authors: | T W B ldicke, G Hillenbrand, E Lanka, W L Staudenbauer |
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| Affiliation: | T W Böldicke, G Hillenbrand, E Lanka, and W L Staudenbauer |
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| Abstract: | The opposite strands of the ColE1 and ColE3 plasmids were isolated as circular single-stranded DNA molecules. These molecules were compared with M13 and phi X174 viral DNA with respect to their capacity to function as templates for in vitro DNA synthesis by a replication enzyme fraction from Escherichia coli. It was found for both ColE plasmids that the conversion of H as well as L strands to duplex DNA molecules closely resembles phi X174 complementary strand synthesis and occurs by a rifampicin-resistant priming mechanism involving the dnaB, dnaC, and dnaG gene products. Restriction analysis of partially double-stranded intermediates indicates that preferred start sites for DNA synthesis are present on both strands of the ColE1 HaeII-C fragment. Inspection of the nucleotide sequence of this region reveals structural similarities with the origin of phi X174 complementary strand synthesis. We propose that the rifampicin-resistant initiation site (rri) in the ColE1 L strand is required for the priming of discontinuous lagging strand synthesis during vegetative replication and that the rri site in the H strand is involved in the initiation of L strand synthesis during conjugative transfer. |
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