The circle is broken: telomere resolution in linear replicons

Linear DNA molecules with covalently closed hairpin ends (telomeres) exist in a wide variety of organisms. Telomere resolution, a DNA breakage and reu nion reaction in which replicated telomeres are processed into hairpin ends , is now known to be a common theme in poxviruses, Borrelia burgdorferi and Escherichia coli phage N15. Candidate proteins that may perform this react ion have recently been identified in poxviruses. Moreover, the first purifi cation and definitive identification of a telomere resolvase has been repor ted for phage N15. This protein is the prototype for a new class of DNA enz yme that performs a unique reaction. Advances in the study of telomere reso lution in poxviruses, B. burgdorferi and E. coli phage N15 are discussed.