Figure 5.

Model for Role of Senataxin and R-Loops in Transcriptional Termination

DNA is shown as solid lines and RNA as a dotted line. R-loops are formed between the ssDNA template strand and nascent RNA behind the elongating Pol II. Vertical black lines denote RNA/DNA hybrids. Senataxin is shown as a gray oval over the R-loop region. R-loops formed over the G-rich pause region of human β-actin gene are necessary for Pol II to pause downstream of the poly(A) site. Senataxin is needed to resolve R-loop structures and so allow 5′–3′ exonuclease Xrn2 to degrade the nascent RNA from the site of poly(A) cleavage and catch up with paused Pol II, causing its transcriptional termination.