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Mol Cell. 2017 Mar 2;65(5):832-847.e4. doi: 10.1016/j.molcel.2017.01.029.

Functions of Replication Protein A as a Sensor of R Loops and a Regulator of RNaseH1.

Author information

1
Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA.
2
Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Electronic address: zou.lee@mgh.harvard.edu.

Abstract

R loop, a transcription intermediate containing RNA:DNA hybrids and displaced single-stranded DNA (ssDNA), has emerged as a major source of genomic instability. RNaseH1, which cleaves the RNA in RNA:DNA hybrids, plays an important role in R loop suppression. Here we show that replication protein A (RPA), an ssDNA-binding protein, interacts with RNaseH1 and colocalizes with both RNaseH1 and R loops in cells. In vitro, purified RPA directly enhances the association of RNaseH1 with RNA:DNA hybrids and stimulates the activity of RNaseH1 on R loops. An RPA binding-defective RNaseH1 mutant is not efficiently stimulated by RPA in vitro, fails to accumulate at R loops in cells, and loses the ability to suppress R loops and associated genomic instability. Thus, in addition to sensing DNA damage and replication stress, RPA is a sensor of R loops and a regulator of RNaseH1, extending the versatile role of RPA in suppression of genomic instability.

KEYWORDS:

R loop; RNase H1; RPA; genome instability; splicing inhibitor; splicing mutation; ssDNA

PMID:
28257700
PMCID:
PMC5507214
DOI:
10.1016/j.molcel.2017.01.029
[Indexed for MEDLINE]
Free PMC Article

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