Gene Loops Enhance Transcriptional Directionality

Abstract

PolII Goes Loopy To execute their function, genes must be transcribed into RNA, often by RNA polymerase II (PolII), which binds at the 5′ end of genes and therefore transcribes through the coding region to make messenger RNA. But, presented with nucleosome-depleted chromatin, PolII will, wastefully, initiate transcription nonspecifically and bidirectionally away from the gene. Noting that actively transcribed genes often form loops, such that their 5′ and 3′ ends are juxtaposed. Tan-Wong et al. (p. 671 , published online 27 September; see the Perspective by Hampsey ) showed that PolII's propensity for promiscuous bidirectional transcription is reined in by gene loop formation.