Phylogenetic Distribution of Prokaryotic Non-Homologous End Joining DNA Repair Systems in Bacteria and Archaea

Nonhomologous end-joining (NHEJ) is a repair mechanism for double strand breaks (DSBs) of DNA. This mechanism is ubiquitously observed within the eukaryotic domain; however, its presence is not as pervasive among prokaryotes and archaea. Notably, in prokaryotes, it has been discerned that multiple distinct NHEJ pathways have evolved in contrast to the singular NHEJ pathway prevalent in eukaryotes. We performed phylogenetic analysis to gain deeper insights into the distribution of these prokaryotic NHEJ pathways. Concurrently, components of the prokaryotic NHEJ pathways were used to find if any archaea carry the genes required and may be able to carry out NHEJ. The results show that few prokaryotes carry the components required for NHEJ, but multiple pathways may be active in a single species. In the context of Archaea, the analysis revealed that a substantial number of species contain fragments or segments of prokaryotic NHEJ elements. Nevertheless, the presence of all the necessary components for the complete execution of the NHEJ pathway remains relatively rare within the archaeal domain.