Rolling-Circle Replication

Saleem A. Khan

doi:10.1128/9781555817732.ch4

Chapter 4 : Rolling-Circle Replication

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Affiliations: 1: Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261

Content Type: Monograph

Publication Year: 2004

Category: Microbial Genetics and Molecular Biology

Book DOI: 10.1128/9781555817732

Chapter DOI: 10.1128/9781555817732.ch4

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Abstract:

Plasmids that replicate by a rolling-circle (RC) mechanism are ubiquitous in gram-positive bacteria and are also found in gram-negative bacteria as well as in Archaea. This chapter discusses the general anatomy of rolling-circle replicating (RCR) plasmids, architecture of the double-strand origin (dso), the single-strand origin (sso), the initiator proteins and their structure-function relationship, key events during the initiation and termination process, and the role of host proteins in plasmid RC replication. It highlights the gaps in the current understanding of the replication of RCR plasmids and possible future lines of research that may uncover these gaps. The first of the RCR plasmids to be identified were native to the gram-positive bacterium, Staphylococcus aureus. The Rep proteins of the pT181 family act as dimers and utilize Tyr-191 of the two monomers in the initiation and termination events. Biochemical analyses using heterodimers of the pT181 RepC protein have provided insights into the role of individual monomers in plasmid RC replication. Elucidation of the three-dimensional structure of plasmid Rep proteins should considerably increase the understanding of the mechanistic aspects of plasmid RC replication. The availability of crystal structures of the initiators of various plasmid families should provide major insights into the mechanisms of initiation and termination of plasmid RC replication.

Citation: Khan S. 2004. Rolling-Circle Replication, p 63-78. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch4

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Rolling-Circle Replication

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Citation: Khan S. 2004. Rolling-Circle Replication, p 63-78. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch4

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Figure 1

Functional organization of RCR plasmids. Four plasmid families represented by pT181, pMV158 (parent of pLS1), pC194, and pSN2 are shown. Arrows indicate the direction of transcription of the various genes or the direction of leading-strand replication from the dso, rep, initiator gene; cop, copy-control gene(s); dso, double-strand origin; sso, single-strand origin; cat and tet, chloramphenicol and tetracycline resistance genes; pre, recombinase gene; mob, mobilization gene.

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Figure 1

Citation: Khan S. 2004. Rolling-Circle Replication, p 63-78. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch4

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Figure 2

A model for plasmid RCR replication. See text for details.

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Figure 2

A model for plasmid RCR replication. See text for details.

Citation: Khan S. 2004. Rolling-Circle Replication, p 63-78. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch4

/content/10.1128/9781555817732.chap4.fig4-3

Figure 3

Folded structures of ssoA's and ssoU. The structures of the pLS1 and pE194 ssoA's are predicted from their sequence while that of the pUB110/pMV158 ssoU has been deduced from the results of nuclease P1 and DNase I mapping experiments. The −10 and −35 regions are indicated, along with the conserved RSB and CS-6 sequences. The initiation sites of primer RNA (pRNA) synthesis are indicated.

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Figure 3

Citation: Khan S. 2004. Rolling-Circle Replication, p 63-78. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch4

/content/10.1128/9781555817732.chap4.fig4-4

Figure 4

An alignment of ssoA, ssoW, ssoT, and ssoU sequences found in various RCR plasmids. Shaded areas indicate nucleotides that are conserved in at least four of the five sso's shown. The −10 and −35 sequences and the conserved RSB sequences are shown. Boxed regions correspond to the conserved CS-6 sequences found in ssoA's and their homologues in other sso types.

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Figure 4

Citation: Khan S. 2004. Rolling-Circle Replication, p 63-78. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch4

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