The balance between R-loops and RNAPII occupancy determines the outcome of transcription-replication conflicts.

In live-cell imaging of a single R-loop–prone locus in yeast, wild-type replisomes cross R-loop enriched transcription units efficiently, and R-loops buffer RNAPII density to prevent replication-blocking RNAPII trains.

• Why it matters: Genome integrity depends on coordinating replication and transcription, but the barrier during transcription-replication conflicts—RNA:DNA hybrids versus stalled RNAPII—has been unclear.
• What they did: The authors monitored R-loop dynamics and RNAPII behavior in real time in yeast, then tested an RNAPII mutant with high DNA affinity while enzymatically removing R-loops.
• The result: R-loops initially repress transcription but replisome passage triggers robust transcription recovery; removing R-loops in the high-DNA-affinity RNAPII mutant causes RNAPII pile-up and a replication barrier more severe than R-loops alone.

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