Nucleosome positioning is critical for gene expression and of major biological interest. The high cost of experimentally mapping nucleosomal arrangement signifies the need for computational approaches to predict nucleosome positions at high resolution. Here, we present a web-based application to fulfill this need by implementing two models, YR and W/S schemes, for the translational and rotational positioning of nucleosomes, respectively. Our methods are based on sequence-dependent anisotropic bending that dictates how DNA is wrapped around a histone octamer. This application allows users to specify a number of options such as schemes and parameters for threading calculation and provides multiple layout formats. The nuMap is implemented in Java/Perl/MySQL and is freely available for public use at http://numap.rit.edu. The user manual, implementation notes, description of the methodology and examples are available at the site.
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http://dx.doi.org/10.1016/j.gpb.2014.08.001 | DOI Listing |
Comput Struct Biotechnol J
December 2024
Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA.
Nullomers are short DNA sequences (11-18 base pairs) that are absent from a genome; however, they can emerge due to mutations. Here, we characterize all possible putative human nullomer-emerging single base pair mutations, population variants and disease-causing mutations. We find that the primary determinants of nullomer emergence in the human genome are the presence of CpG dinucleotides and methylated cytosines.
View Article and Find Full Text PDFElife
January 2025
Translational Science and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, United States.
The association between late replication timing and low transcription rates in eukaryotic heterochromatin is well known, yet the specific mechanisms underlying this link remain uncertain. In , the histone deacetylase Sir2 is required for both transcriptional silencing and late replication at the repetitive ribosomal DNA (rDNA) arrays. We have previously reported that in the absence of , a de-repressed RNA PolII repositions MCM replicative helicases from their loading site at the ribosomal origin, where they abut well-positioned, high-occupancy nucleosomes, to an adjacent region with lower nucleosome occupancy.
View Article and Find Full Text PDFPLoS One
January 2025
Mandel Center for Heart and Vascular Research, The Duke Cardiovascular Research Center, Duke University Medical Center, Durham, NC, United States of America.
Early events in the reprogramming of fibroblasts to cardiac muscle cells are unclear. While various histone undergo modification and re-positioning, and these correlate with the activity of certain genes, it is unknown if these events are causal or happen in response to reprogramming. Histone modification and re-positioning would be expected to open up chromatin on lineage-specific genes and this can be ascertained by studying nucleosome architecture.
View Article and Find Full Text PDFGene
January 2025
Department of Biotechnology, Pondicherry Central University, Pondicherry 605014, India.
The PWWP domain is a conserved motif unique to eukaryotes, playing a critical role in various cellular processes. Proteins containing the PWWP domain are typically found in chromatin, where they bind to DNA and histones in nucleosomes, facilitating chromatin-associated functions. Among these proteins, PWWP-domain containing proteins 2A and 2B (PWWP2A and PWWP2B), identified during the H2A interactome analysis, are DNA methyltransferase-related proteins, that are structurally disordered, except for their PWWP domain.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA.
In eukaryotic nuclei, DNA is wrapped around an octamer of core histones to form nucleosomes. H1 binds to the linker DNA of nucleosome to form the chromatosome, the next structural unit of chromatin. Structural features on individual chromatosomes contribute to chromatin structure, but not fully characterized.
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