Human Senataxin Resolves RNA/DNA Hybrids Formed at Transcriptional Pause Sites to Promote Xrn2-Dependent Termination
نویسندگان
چکیده
We present a molecular dissection of pause site-dependent transcriptional termination for mammalian RNA polymerase II (Pol II)-transcribed genes. We show that nascent transcripts form RNA/DNA hybrid structures (R-loops) behind elongating Pol II and are especially prevalent over G-rich pause sites positioned downstream of gene poly(A) signals. Senataxin, a helicase protein associated with AOA2/ALS4 neurodegenerative disorders, acts to resolve these R-loop structures and by so doing allows access of the 5'-3' exonuclease Xrn2 at 3' cleavage poly(A) sites. This affords 3' transcript degradation and consequent Pol II termination. In effect, R-loops formed over G-rich pause sites, followed by their resolution by senataxin, are key steps in the termination process.
منابع مشابه
Pause sites promote transcriptional termination of mammalian RNA polymerase II.
Polymerase II (Pol II) transcriptional termination depends on two independent genetic elements: poly(A) signals and downstream terminator sequences. The latter may either promote cotranscriptional RNA cleavage or pause elongating Pol II. We demonstrate that the previously characterized MAZ4 pause element promotes Pol II termination downstream of a poly(A) signal, dependent on both the proximity...
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