PMID: 17603014.-- Final version of the paper available at: http://www.sciencedirect.com/science/journal/0006291X
Transcription elongation causes a local change in DNA superhelicity. An excess of negative supercoiling may lead to opening of DNA strands that could allow formation of R-loops. In yeast, mutants of the THO complex are impaired in transcription elongation and this defect has been linked to co-transcriptional formation of R-loops, which could constitute roadblocks for RNA polymerases. In this study, we found that stably formed 300-nt long DNA–RNA hybrids in a negatively supercoiled transcription template reduced the efficiency of transcription elongation by half, providing a first experimental evidence that transcription elongation is impaired by R-loops in vitro.
This work was supported by grants of the Spanish Ministry of Science and Education (GEN2001-4707-C08-02 and SAF2003-00204) and Junta de Andalucía (CVI102).
Peer reviewed