Department of Biochemistry & Molecular Biology, The University of Calgary, Calgary, AB T2N 4N1, Canada.
Annu Rev Microbiol. 2010;64:185-202. doi: 10.1146/annurev.micro.112408.134037.
Spirochetes of the genus Borrelia include important human pathogens that cause Lyme borreliosis and relapsing fever. The genomes of Borrelia species can be composed of up to 24 DNA molecules, most of which are linear. The plasmid content and linear replicon sequence arrangement vary widely between isolates. The linear replicons are terminated by covalently closed DNA hairpins or hairpin telomeres. Replication of these elements involves a unique reaction, called telomere resolution, to produce hairpin telomeres from replicative intermediates. The telomere resolvase, ResT, is thought to contribute to the genetic flux of the linear molecules by promoting stabilized telomere fusions. Telomere resolvases are related to the tyrosine recombinases and ResT can generate the crucial reaction intermediate of this class of enzyme, the Holliday junction. This observation has led to the proposal that telomere resolvases evolved from tyrosine recombinases inducing DNA linearization in the genomes that acquired them.
螺旋体属的螺旋体包括重要的人类病原体，它们引起莱姆病和回归热。 螺旋体物种的基因组可以由多达 24 个 DNA 分子组成，其中大多数是线性的。 质粒含量和线性复制子序列排列在分离株之间差异很大。 线性复制子由共价闭合的 DNA 发夹或发夹端粒终止。 这些元件的复制涉及一种独特的反应，称为端粒分辨率，从复制中间体产生发夹端粒。 端粒核酸内切酶 ResT 被认为通过促进稳定的端粒融合来促进线性分子的遗传流动。 端粒核酸内切酶与酪氨酸重组酶有关，ResT 可以产生该酶类的关键反应中间体，即 Holliday 连接。 这一观察结果导致提出端粒核酸内切酶是从酪氨酸重组酶进化而来的，酪氨酸重组酶在获得它们的基因组中诱导 DNA 线性化。
