The rapid delivery of RNase H variants reveals distinct classes of RNA:DNA hybrids.

Rapid delivery of RNase H variants reveals distinct classes of RNA:DNA hybrids that are differentially sensitive to RNase H1 activity in live cells.

• Why it matters: Understanding how RNA:DNA hybrids affect replication fork stability is crucial, as they can disrupt replication restart and genome integrity. Current methods lack the ability to distinguish direct effects of hybrids from indirect consequences, limiting insight into their specific roles.
• What they did: Researchers developed iCoRD to quickly deliver RNase H1 or control proteins into live cells, enabling in situ recognition and removal of RNA:DNA hybrids without significantly altering the transcriptome. They observed effects on stress-induced, fork-proximal hybrids and R-ChIP signals but not on DRIP or S9.6 Cut&Tag signals.
• The result: Findings suggest the existence of distinct RNA:DNA hybrid populations that are differentially mapped and sensitive to RNase H1, providing new insights into hybrid heterogeneity and detection methods.