Interplay between the transcription preinitiation complex and the +1 nucleosome

Abstract

Eukaryotic transcription starts with the assembly of a preinitiation complex (PIC) on core promoters. Flanking this region is the +1 nucleosome, the first nucleosome downstream of the core promoter. While this nucleosome is rich in epigenetic marks and plays a key role in transcription regulation, how the +1 nucleosome interacts with the transcription machinery has been a long-standing question. Here, we summarize recent structural and functional studies of the +1 nucleosome in complex with the PIC. We specifically focus on how differently organized promoter–nucleosome templates affect the assembly of the PIC and PIC-Mediator on chromatin and result in distinct transcription initiation.