Which strand of a plasmid is replicated?

tfitzwater at gilead.com tfitzwater at gilead.com
Thu Sep 14 13:35:59 EST 2000


>From: tfitzwater at gilead.com
>Date: Wed 13 Sep 2000 - 20:40:38 BST

>Leading strand synthesis of ColE 1-type plasmids is directed by the Primer
>RNA, which begins with the sequence 5' GCAAACAAAAAAACC... and ends 555
>nucleotides later with the sequence ...GGGGGGCGGACCUAUGGAAA 3'. DNA
>replication starts from RNase H cuts made at the final 3 A residues and
>continues around the plasmid. Lagging strand replication starts at about
>position 720 downstream from the start of Primer RNA transcription and is
>halted at about position 525 on the non-template strand until the
>replication fork passes that position. Lagging strand synthesis then
>continues until two concatenated double-stranded plasmids result. These
>are then resolved into separate entities.


I was asked for references.  Here are 3:

Nakasu, S. and Tomizawa, J.,1992. Structure of the ColE1 DNA molecule
before segregation to daughter molecules.  Proc. Natl. Acad. Sci. USA
89:10139-43.

Fitzwater, T., Yang, Y. L., Zhang, X. Y. and Polisky, B., 1992.  Mutations
affecting RNA-DNA hybrid formation of the ColE1 replication primer RNA.
Restoration of RNA I sensitivity to a copy-number mutant by second-site
mutations.  J. Mol. Biol. 226:  997-1008.

Eguchi, Y., Itoh, T. and Tomizawa, J., 1991.  Antisense RNA.  Annu. Rev.
Biochem. 60:631-652.


Tim Fitzwater
Principal Research Associate
Gilead Sciences


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