TRANSCRIPTION, TOPOISOMERASES AND RECOMBINATION

Transcription, DNA topoisomerases and genetic recombination are interr elated for several structural reasons. Transcription can affect DNA to pology, resulting in effects on recombination. It can also affect the chromatin structure in which the DNA resides. Topoisomerases can affec t DNA and/or chromatin structure influencing the recombination potenti al at a given site. Here we briefly review the extent to which homolog ous direct repeat recombination and site-specific recombination in euk aryotes are affected by transcription and topoisomerases. In some case s, transcription pr the absence of topoisomerases have little or no ef fect on recombination. In others, they are important components in the recombinational process. The common denominator of any effects of tra nscription and topoisomerases on recombination is their shared role in altering DNA topology.