Homologous recombination in Archaea: new Holliday junction helicases

Homologous recombination (HR) maintains genome stability by promoting high fidelity DNA repair. Several recent reports have established that the primary function of HR enzymes is to underpin DNA replication, resetting forks that are blocked or collapsed at sites of DNA damage remote from replication origins. These functions are crucial to ensuring that genomes are transmitted successfully into subsequent generations of cells. Enzymes of HR have been unearthed in all three domains of life: bacteria, Archaea and eukarya. Helicases that specifically unwind branched DNA molecules are pivotal in linking HR and DNA replication in bacteria. However, knowledge of helicases with these functions in eukaryotes is vague and is wholly absent in Archaea. We are using the archaeal species Methanothermobacter thermautotrophicus to identify new DNA helicases of homologous recombination.