Search

Chromobox 2 (CBX2), a component of polycomb repressive complex 1 (PRC1), binds lysine 27-methylated histone H3 (H3K27me3) via its chromodomain (CD) and plays a critical role in repressing developmentally regulated genes. The phosphorylation of CBX2 has been described in several studies, but the biological implications of this modification remain largely elusive. Here, we show that CBX2's phosphorylation plays an important role in its nucleosome binding. CBX2 is stably phosphorylated in vivo, and domain analysis showed that residues in CBX2's serine-rich (SR) region are the predominant phosphorylation sites. The serine residues in an SR region followed by an acidicresidue (AR) cluster coincide with the consensus target of casein kinase II (CK2), and CK2 efficiently phosphorylated the SR region in vitro. A nucleosome pulldown assay revealed that CK2-phosphorylated CBX2 had a high specificity for H3K27me3-modified nucleosomes. An electrophoretic mobility-shift assay showed that CK2-mediated phosphorylation diminished CBX2's AT-hook-associated DNA-binding activity. Mutant CBX2 lacking the SR region or its neighboring AR cluster failed to repress the transcription of p21, a gene targeted by PRC1. These results suggest that CBX2's phosphorylation is critical for its transcriptional repression of target genes. [ABSTRACT FROM AUTHOR]

SUV39H is the major histone H3 lysine 9 (H3K9)-specific methyltransferase that targets pericentric regions and is crucial for assembling silent heterochromatin. SUV39H recognizes trimethylated H3K9 (H3K9me3) via its chromodomain (CD), and enriched H3K9me3 allows SUV39H to target specific chromosomal regions. However, the detailed targeting mechanisms, especially for naïve chromatin without preexisting H3K9me3, are poorly understood. Here we show that Suv39h1's CD (Suv39h1-CD) binds nucleic acids, and this binding is important for its function in heterochromatin assembly. Suv39h1-CD had higher binding affinity for RNA than DNA, and its ability to bind nucleic acids was independent of its H3K9me3 recognition. Suv39h1 bound major satellite RNAs in vivo, and knockdown of major satellite RNAs lowered Suv39h1 retention on pericentromere. Suv39h1 mutational studies indicated that both the nucleic acid-binding and H3K9me-binding activities of Suv39h1-CD were crucial for its pericentric heterochromatin assembly. These results suggest that chromatin-bound RNAs contribute to creating SUV39H's target specificity. [ABSTRACT FROM AUTHOR]

The rapid development of wind energy in Japan and the associated high uncertainties and fluctuations in power generation present a big challenge for both wind power generators and electric grids. Accurate and reliable wind power predictions are necessary to optimize the integration of wind power into existing electrical systems. In this study, a hybrid forecasting system of wind power generation was developed by integrating the Kalman filter (KF) with the high resolution Weather Research and Forecasting (WRF) model as well as an empirical formula of wind power output (power curve). The system has been validated with observations including wind speed and power output over a six-month period for 15 turbine sites at a wind farm in Awaji-island, Japan. The results show that the tuned WRF model is able to provide hub-height wind speed prediction for the target area with reliability to some extent. The predicted wind field can be substantially improved by the Kalman filter as a post-processing procedure. The 15-turbine averaged improvements of mean error, root mean square error, and correlation coefficient are 97%, 22%, and 10%, respectively. Meanwhile, the Kalman filter also demonstrates a promising capability of reducing the uncertainties in the power curve model. Systematic validations regarding both wind speed and power output were carried out against the observations for the target wind farm, which show that the hybrid power forecasting system presented in this paper can be an effective and practical tool for short-term predictions of wind speed and power output in Japan area. [ABSTRACT FROM AUTHOR]