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Histone Tails (histone + tail)
Selected AbstractsMolecular dynamics simulation on HP1 protein binding by histone H3 tail methylation and phosphorylationINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2009Yan-Ke Jiang Abstract Trimethylation of histone H3 lysine 9 is important for recruiting heterochromatin protein 1 (HP1) to discrete regions of the genome, thereby regulating gene expression, chromatin packaging, and heterochromatin formation. Phosphorylation of histone H3 has been linked with mitotic chromatin condensation. During mitosis in vivo, H3 lysine 9 methylation and serine 10 phosphorylation can occur concomitantly on the same histone tail, whereas the influence of phosphorylation to trimethylation H3 tail recruiting HP1 remains controversial. In this work, molecular dynamics simulation of HP1 complexed with both trimethylated and phosphorylated H3 tail were performed and compared with the results from the previous methylated H3-HP1 trajectory. It is clear from the 10-ns dynamics simulation that two adjacent posttranslational modifications directly increase the flexibility of the H3 tail and weaken HP1 binding to chromatin. A combinatorial readout of two adjacent posttranslational modifications,a stable methylation and a dynamic phosphorylation mark,establish a regulatory mechanism of protein,protein interactions. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Quantum chemical modeling of enzymatic reactions: The case of histone lysine methyltransferaseJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2010Polina Georgieva Abstract Quantum chemical cluster models of enzyme active sites are today an important and powerful tool in the study of various aspects of enzymatic reactivity. This methodology has been applied to a wide spectrum of reactions and many important mechanistic problems have been solved. Herein, we report a systematic study of the reaction mechanism of the histone lysine methyltransferase (HKMT) SET7/9 enzyme, which catalyzes the methylation of the N-terminal histone tail of the chromatin structure. In this study, HKMT SET7/9 serves as a representative case to examine the modeling approach for the important class of methyl transfer enzymes. Active site models of different sizes are used to evaluate the methodology. In particular, the dependence of the calculated energies on the model size, the influence of the dielectric medium, and the particular choice of the dielectric constant are discussed. In addition, we examine the validity of some technical aspects, such as geometry optimization in solvent or with a large basis set, and the use of different density functional methods. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] The Human Histone Acetyltransferase P/CAF is a Promiscuous Histone PropionyltransferaseCHEMBIOCHEM, Issue 4 2008Hans Leemhuis Dr. Catalytic promiscuity: The human histone acetyltransferase P/CAF can confer propionyl instead of acetyl marks onto peptides that mimic the H3 histone tail. Catalysis of propionyl transfer occurs with a kcat of 8.8 min,1 (versus a kcat of 12 min,1 observed for the transfer of an acetyl group) and with identical specificity for individual lysine residues in the H3 sequence. [source] Theoretical framework for the histone modification network: modifications in the unstructured histone tails form a robust scale-free networkGENES TO CELLS, Issue 7 2009Yohei Hayashi A rapid increase in research on the relationship between histone modifications and their subsequent reactions in the nucleus has revealed that the histone modification system is complex, and robust against point mutations. The prevailing theoretical framework (the histone code hypothesis) is inadequate to explain either the complexity or robustness, making the formulation of a new theoretical framework both necessary and desirable. Here, we develop a model of the regulatory network of histone modifications in which we encode histone modifications as nodes and regulatory interactions between histone modifications as links. This network has scale-free properties and subnetworks with a pseudo,mirror symmetry structure, which supports the robustness of the histone modification network. In addition, we show that the unstructured tail regions of histones are suitable for the acquisition of this scale-free property. Our model and related insights provide the first framework for an overall architecture of a histone modification network system, particularly with regard to the structural and functional roles of the unstructured histone tail region. In general, the post-translational "modification webs" of natively unfolded regions (proteins) may function as signal routers for the robust processing of the large amounts of signaling information. [source] RBP2 is an MRG15 complex component and down-regulates intragenic histone H3 lysine 4 methylationGENES TO CELLS, Issue 6 2007Tomohiro Hayakawa MRG15 is a conserved chromodomain protein that associates with histone deacetylases (HDACs) and Tip60-containing histone acetyltransferase (HAT) complexes. Here we further characterize MRG15-containing complexes and show a functional link between MRG15 and histone H3K4 demethylase activity in mammalian cells. MRG15 was predominantly localized to discrete nuclear subdomains enriched for Ser2 -phosphorylated RNA polymerase II, suggesting it is involved specifically with active transcription. Protein analysis of the MRG15-containing complexes led to the identification of RBP2, a JmjC domain-containing protein. Remarkably, over-expression of RBP2 greatly reduced the H3K4 methylation in culture human cells in vivo, and recombinant RBP2 efficiently removed H3K4 methylation of histone tails in vitro. Knockdown of RBP2 resulted in increased H3K4 methylation levels within transcribed regions of active genes. Our findings demonstrate that RBP2 associated with MRG15 complex to maintain reduced H3K4 methylation at transcribed regions, which may ensure the transcriptional elongation state. [source] Journal of Cellular Physiology: Volume 224, Number 2, August 2010JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2010Article first published online: 5 AUG 2010 The cover shows acetylation sites, located on the histone tails and on the structured regions. See "Mini-Review" in this issue by Hansen et al, pages 289,299. [source] Asymmetries in the nucleosome core particle at 2.5,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2000Joel M. Harp The 2.5,Å X-ray crystal structure of the nucleosome core particle presented here provides significant additions to the understanding of the nucleosome, the fundamental unit of chromatin structure. Extensions are made to the structure of the N-terminal histone tails and details are provided on hydration and ion binding. The structure is composed of twofold symmetric molecules, native chicken histone octamer cores and the DNA palindrome, which were expected to form a perfectly twofold symmetric nucleosome core particle. In fact, the result is asymmetric owing to the binding of the DNA to the protein surface and to the packing of the particles in the crystal lattice. An analysis is made of the asymmetries by comparisons both within the nucleosome core particle and to the structure of the histone octamer core of the nucleosome. [source] Electrostatic interactions with histone tails may bend linker DNA in chromatinBIOPOLYMERS, Issue 1 2006Angelo Perico Abstract Is linker DNA bent in the 30-nm chromatin fiber at physiological conditions? We show here that electrostatic interactions between linker DNA and histone tails including salt condensation and release may bend linker DNA, thus affecting the higher order organization of chromatin. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 20,28, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | |||||||||||||