Related Experiment Video
Updated: May 29, 2025
04:37
High-Pressure NMR Experiments for Detecting Protein Low-Lying Conformational States
Published on: June 29, 2021
2.6K
Solution conformational differences between conventional and CENP-A nucleosomes are accentuated by reversible
Kushol Gupta1, Nikolina Sekulić1,2, Praveen Kumar Allu1
1Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059, USA.
Biorxiv : the Preprint Server for Biology
|February 3, 2025
Summary
Histone identity and DNA sequence impact nucleosome stability under pressure. Centromeric nucleosomes with CENP-A are more stable than canonical ones, showing less unwrapping.
Area of Science:
- Structural Biology
- Biophysics
- Chromatin Biology
Background:
- Nucleosomes, fundamental units of DNA packaging, have been studied using scattering techniques.
- Centromeric nucleosomes, containing CENP-A, differ from canonical nucleosomes and play roles in chromosome segregation.
Purpose of the Study:
- To compare the solution properties and stability of canonical (H3) and centromeric (CENP-A) nucleosomes.
- To investigate the impact of histone variant and DNA sequence on nucleosome structure under high pressure.
Main Methods:
- Analytical Ultracentrifugation (AUC) for native solution properties.
- Small-Angle X-ray Scattering (SAXS) and Contrast Variation Small-Angle Neutron Scattering (CV-SANS) for structural analysis.
- High-Pressure SAXS (HP-SAXS) to assess stability under pressure (300 MPa).
Main Results:
- Established native solution properties of H3 and CENP-A nucleosome core particles (NCPs).
- HP-SAXS revealed histone identity and DNA sequence influence nucleosome stability and induce reversible unwrapping.
- Centromeric nucleosomes exhibited a less pronounced increase in radius of gyration under pressure compared to canonical nucleosomes.
Conclusions:
- Histone variant (H3 vs. CENP-A) and DNA sequence significantly affect nucleosome stability in solution.
- HP-SAXS offers a powerful solution-based method for studying nucleosome and chromatin complex dynamics and stability.
Related Concept Videos
02:30Histone Variants at the Centromere
4.3K
Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3...
4.3K
02:10The Nucleosome Core Particle
11.9K
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
11.9K
01:19The Nucleosome
1.3K
Human DNA is almost two meters long. However, it is compressed inside a tiny nucleus measuring only a few microns in diameter. To make this degree of compaction possible, DNA is organized into several sequential levels so that it can fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
1.3K
02:54Nucleosome Remodeling
8.9K
Nucleosomes are the basic units of chromatin compaction. Each nucleosome consists of the DNA bound tightly around a histone core, which makes the DNA inaccessible to DNA binding proteins such as DNA polymerase and RNA polymerase. Hence, the fundamental problem is to ensure access to DNA when appropriate, despite the compact and protective chromatin structure.
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
8.9K
01:01Euchromatin
6.8K
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
6.8K
02:38Heterochromatin
10.0K
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at...
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at...
10.0K