Abstract
ABSTRACTThe integration of mobile genetic elements into their host chromosome influences the immediate fate of cellular organisms and gradually shapes their evolution. Site-specific recombinases catalyzing this integration have been extensively characterized both in bacteria and eukarya. More recently, a number of reports provided the in-depth characterization of archaeal tyrosine recombinases and highlighted new particular features not observed in the other two domains. In addition to being active in extreme environments, archaeal integrases catalyze reactions beyond site-specific recombination. Some of these integrases can catalyze low-sequence specificity recombination reactions with the same outcome as homologous recombination events generating deep rearrangements of their host genome. A large proportion of archaeal integrases are termed suicidal due to the presence of a specific recombination target within their own gene. The paradoxical maintenance of integrases that disrupt their gene upon integration implies novel mechanisms for their evolution. In this review, we assess the diversity of the archaeal tyrosine recombinases using a phylogenomic analysis based on an exhaustive similarity network. We outline the biochemical, ecological and evolutionary properties of these enzymes in the context of the families we identified and emphasize similarities and differences between archaeal recombinases and their bacterial and eukaryal counterparts.
Highlights
Recombination of DNA is an essential mechanism ensuring the maintenance, propagation and evolution of genetic information in all living organisms
In addition to the first two types of tyrosine recombinases that correspond to bona fide integrases, the majority archaeal genomes possess the XerA site-specific recombinase that, as the bacterial XerC/D homologs, resolves chromosome dimers occurring during DNA replication (Cortez et al 2010)
Our results indicated that no archaeal integrases belong to the group of eukaryotic-like topoisomerases IB, even though a conserved structure between eukaryotic topoisomerase I and the catalytic domain bacterial tyrosine recombinases was reported (Cheng et al 1998)
Summary
Recombination of DNA is an essential mechanism ensuring the maintenance, propagation and evolution of genetic information in all living organisms. A systematic genomic search for sequences encoding the more conserved catalytic domain identified a number of archaeal integrases of this type that could be ranked in five families (She, Brugger and Chen 2002). In addition to the first two types of tyrosine recombinases that correspond to bona fide integrases, the majority archaeal genomes possess the XerA ( named XerC) site-specific recombinase that, as the bacterial XerC/D homologs, resolves chromosome dimers occurring during DNA replication (Cortez et al 2010).
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