Identification of nucleosome assembly protein 1 (NAP1) as an interacting partner of plant ribosomal protein S6 (RPS6) and a positive regulator of rDNA transcription

• Published in: Biochemical and biophysical research communications 2015-09, Vol.465 (2), p.200-205
• Main Authors: Son, Ora, Kim, Sunghan, Shin, Yun-jeong, Kim, Woo-Young, Koh, Hee-Jong, Cheon, Choong-Ill
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; ARABIDOPSIS; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding Sites; DNA, Ribosomal - genetics; DNA, Ribosomal - metabolism; FLUORESCENCE; Gene Expression Regulation, Plant; Genes, Reporter; Histone deacetylase 2B; Histone Deacetylases - genetics; Histone Deacetylases - metabolism; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Nucleosome assembly protein 1; Nucleosomes - genetics; Nucleosomes - metabolism; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; Protein Binding; PROTEINS; Protoplasts - metabolism; rDNA transcription; Ribosomal protein S6; Ribosomes - genetics; Ribosomes - metabolism; Signal Transduction; SIGNALS; TOR; TRANSCRIPTION; Transcription, Genetic
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2015.07.150

The ribosomal protein S6 (RPS6) is a downstream component of the signaling mediated by the target of rapamycin (TOR) kinase that acts as a central regulator of the key metabolic processes, such as protein translation and ribosome biogenesis, in response to various environmental cues. In our previous study, we identified a novel role of plant RPS6, which negatively regulates rDNA transcription, forming a complex with a plant-specific histone deacetylase, AtHD2B. Here we report that the Arabidopsis RPS6 interacts additionally with a histone chaperone, nucleosome assembly protein 1(AtNAP1;1). The interaction does not appear to preclude the association of RPS6 with AtHD2B, as the AtNAP1 was also able to interact with AtHD2B as well as with an RPS6-AtHD2B fusion protein in the BiFC assay and pulldown experiment. Similar to a positive effect of the ribosomal S6 kinase 1 (AtS6K1) on rDNA transcription observed in this study, overexpression or down regulation of the AtNAP1;1 resulted in concomitant increase and decrease, respectively, in rDNA transcription suggesting a positive regulatory role played by AtNAP1 in plant rDNA transcription, possibly through derepression of the negative effect of the RPS6-AtHD2B complex. •Nucleosome assembly protein 1 (AtNAP1) interacts with RPS6 as well as with AtHD2B.•rDNA transcription is regulated S6K1.•Overexpression or down regulation of AtNAP1 results in concomitant increase or decrease in rDNA transcription.