Transcription, topoisomerases and recombination

Transcription, DNA topoisomerases and genetic recombination are interrelated for several structural reasons. Transcription can affect DNA topology, resulting in effects on recombination. It can also affect the chromatin structure in which the DNA resides. Topoisomerases can affect DNA and/or chromatin structure influencing the recombination potential at a given site. Here we briefly review the extent to which homologous direct repeat recombination and site-specific recombination in eukaryotes are affected by transcription and topoisomerases. In some cases, transcription or the absence of topoisomerases have little or no effect on recombination. In others, they are important components in the recombinational process. The common denominator of any effects of transcription and topoisomerases on recombination is their shared role in altering DNA topology.