Perspectives

One fully expects that continued study of telomere biology and plasmid replication/segregation at the molecular biology and biochemical level will

A Fig. 4 Schematic summary of the telomere resolution reaction catalysed by ResT. Initial binding of ResT (step 1) to the rTel in a substrate lacking positive supercoiling is non-cooperative (Bankhead et al. 2006). Introduction of positive twist by some resolutioncoupled cellular process in vivo or by thermal fluctuation or reverse gyrase in vitro facilitates ResT-ResT communication and the formation of a cross-axis complex (step 2). No specific architecture for the interactions in the cross-axis complex should be inferred by the schematic depiction presented. In step 3 of the reaction the hairpin-binding module (HBM) induces a distortion of the DNA between the cleavage sites. This is represented as strand separation between the cleavage sites due to the fact that heteroduplexed substrates rescue HBM mutants. The actual structural nature of the distortion induced has yet to be characterized. The action of the HBM licenses cleavage of both DNA strands (step 4) and facilitates the conformational change (step 5) required for hairpin formation (step 6). Once the DNA strands are cleaved, steps 5 and 6 follow without the possibility of resealing strands in the parental configuration (Kobryn et al. 2005). This approach to hairpin formation may be imposed by dissipation of the positive twist used to build the cross-axis complex. The hp telomeres are depicted after product release. The time frame for this step of the reaction is unknown continue to shed light on such diverse topics as the origin and role of genome linearity, genome evolution and pathogenesis in the fascinating spirochetes of the genus Borrelia.

Acknowledgements KK is supported by a grant from the Canadian Institutes of Health Research (CIHR). I would like to thank George Chaconas for communication of unpublished results and Brendan Bell for critical reading of the manuscript.

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