Gene capture in archaeal chromosomes.

Free genetic elements can be readily integrated into bacterial chromosomes, but so far, with the exception of one virus, there has been no evidence that this happens in Archaea — the other domain of microorganisms. Here we show that site-specific integration of different genetic elements into archaeal chromosomes is a general phenomenon, albeit rare, which requires an archaeal integrase and produces a partitioned integrase gene in the chromosome. The process is distinct from bacterial mechanisms and has implications for how horizontal gene transfer might occur across the boundaries of the domains of life.