Abstract
Identifying how R-loops are generated is crucial to know how transcription compromises genome integrity. We show by genome-wide analysis of conditional yeast mutants that the THO transcription complex, prevents R-loop formation in G1 and S-phase, whereas the Sen1 DNA-RNA helicase prevents them only in S-phase. Interestingly, damage accumulates asymmetrically downstream of the replication fork in sen1 cells but symmetrically in the hpr1 THO mutant. Our results indicate that: R-loops form co-transcriptionally independently of DNA replication; that THO is a general and cell-cycle independent safeguard against R-loops, and that Sen1, in contrast to previously believed, is an S-phase-specific R-loop resolvase. These conclusions have important implications for the mechanism of R-loop formation and the role of other factors reported to affect on R-loop homeostasis.
© 2021. The Author(s).
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Cycle / genetics
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Cell Cycle / physiology
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DNA Damage
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DNA Helicases / genetics
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DNA Helicases / metabolism
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DNA, Fungal / chemistry*
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DNA, Fungal / genetics
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DNA, Fungal / metabolism
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Genes, Fungal
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Genomic Instability
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Models, Biological
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Mutation
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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R-Loop Structures* / genetics
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R-Loop Structures* / physiology
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RNA Helicases / genetics
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RNA Helicases / metabolism
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RNA, Fungal / chemistry*
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RNA, Fungal / genetics
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RNA, Fungal / metabolism
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Saccharomyces cerevisiae / chemistry
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
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Transcription Factors / genetics
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Transcription Factors / metabolism
Substances
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DNA, Fungal
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HPR1 protein, S cerevisiae
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Nuclear Proteins
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RNA, Fungal
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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SEN1 protein, S cerevisiae
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DNA Helicases
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RNA Helicases