Global Analysis of Short RNAs Reveals Widespread Promoter-Proximal Stalling and Arrest of Pol II in Drosophila

Abstract

To Stall or Not to Stall Recent studies in mammals and Drosophila have shown that RNA polymerase II frequently stalls shortly after initiating messenger RNA synthesis and that this stalling is important for proper expression of genes. Although several protein factors that affect polymerase stalling are known, the role of DNA sequence in this process has remained unclear. Now Nechaev et al. (p. 335 , published online 10 December) report that the initially transcribed sequences of many genes contain a signal that works like a stop sign for the elongating polymerase. Expression of genes may thus be regulated by a combination of a DNA signal that induces promoter-proximal stalling and protein factors that alter its duration.