Role of the Nhp6 Protein in In Vitro Transcription through the Nucleosome

Nhp6 is a small yeast protein that binds DNA nonspecifically. It has been shown that Nhp6 is a component of several protein complexes (including the FACT complex) and is present on many yeast promoters and transcribed regions of genes in vivo. It also participates in the process of destabilizing the structure of nucleosomes in vitro. In our laboratory, we studied the FACT complex and showed its role in transcription by eukaryotic RNA polymerase 2 in vitro. However, the role of the Nhp6 protein in transcription has not been studied previously. In this paper, we describe the effect of the Nhp6 protein on transcription through the nucleosome by eukaryotic RNA polymerase 2 and show that the Nhp6 protein increases the transcription efficiency at several positions on nucleosomal DNA, primarily the transcription at positions +(11–17) in the nucleosome. We proposed a model of the Nhp6 action during transcription through chromatin. The model suggests the stabilization of transient DNA uncoiling from the octamer during this process.