Nucleosomes represent a physical barrier for cleavage activity of DNA topoisomerase I in vivo

Francesca Di Felice , Francesco Chiani , Giorgio Camilloni (1)

1 Genetica e Biologia Molecolare

DNA topoisomerase I together with the other cellular DNA topoisomerases releases the torsional stress from DNA caused by processes such as replication, transcription and recombination. Despite the well defined knowledge of its mechanism of action, DNA topoisomerase I in vivo activity has been only partially characterized. In fact the basic question concerning the capability of the enzyme to cleave and rejoin DNA wrapped around histone octamer remains still unanswered. By studying both in vivo and in vitro the cleavage activity of DNA topoisomerase I in the presence of camptothecin on a repeated trinucleotide sequence, (TTA) 35}, lying in the chromosome XIII of Saccharomyces cerevisiae, we can conclude that nucleosomes represent a physical barrier for the enzyme activity.

Mots clés: Life Sciences

Francesca Di Felice, Francesco Chiani, Giorgio Camilloni. Nucleosomes represent a physical barrier for cleavage activity of DNA topoisomerase I in vivo. Biochemical Journal, 2007, 409 (3), pp.651-656. ⟨10.1042/BJ20070893⟩. ⟨hal-00478842⟩