title: Differential telomere processing by Borrelia telomere resolvases in vitro but not in vivo.
abstract: Causative agents of Lyme disease and relapsing fever, including Borrelia burgdorferi and Borrelia hermsii, respectively, are unusual among bacteria in that they possess a segmented genome with linear DNA molecules terminated by hairpin ends, known as telomeres. During replication, these telomeres are processed by the essential telomere resolvase, ResT, in a unique biochemical reaction known as telomere resolution. In this study, we report the identification of the B. hermsii resT gene through cross-species hybridization. Sequence comparison of the B. hermsii protein with the B. burgdorferi orthologue revealed 67% identity, including all the regions currently known to be crucial for telomere resolution. In vitro studies, however, indicated that B. hermsii ResT was unable to process a replicated B. burgdorferi type 2 telomere substrate. In contrast, in vivo cross-species complementation in which the native resT gene of B. burgdorferi was replaced with B. hermsii resT had no discernible effect, even though B. burgdorferi strain B31 carries at least two type 2 telomere ends. The B. burgdorferi ResT protein was also able to process two telomere spacing mutants in vivo that were unresolvable in vitro. The unexpected differential telomere processing in vivo versus in vitro by the two telomere resolvases suggests the presence of one or more accessory factors in vivo that are normally involved in the reaction. Our current results are also expected to facilitate further studies into ResT structure and function, including possible interaction with other Borrelia proteins.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1 Canada.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Tourand
authors.forename: Troy
authors.initials: T
authors.lastname: Bankhead
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Wilson
authors.forename: Adrienne D
authors.initials: AD
authors.lastname: Putteet-Driver
authors.forename: Alan G
authors.initials: AG
authors.lastname: Barbour
authors.forename: Rebecca
authors.initials: R
authors.lastname: Byram
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Rosa
authors.forename: George
authors.initials: G
authors.lastname: Chaconas
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001898:Borrelia / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D016615:Telomere / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004706:Endodeoxyribonucleases; C446515:ResT protein, Borrelia