Related Experiment Video
Updated: May 11, 2026
09:02
Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A)
Published on: June 10, 2020
CENP-A confers a reduction in height on octameric nucleosomes
Matthew D D Miell1, Colin J Fuller, Annika Guse
1Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, UK.
Nature Structural & Molecular Biology
|May 7, 2013
Summary
Centromere protein A (CENP-A) nucleosomes, crucial for kinetochore assembly, are physically distinct from canonical histone H3 nucleosomes. This study shows octameric CENP-A nucleosomes have reduced heights, challenging hemisome theories.
Area of Science:
- Molecular Biology
- Epigenetics
- Chromatin Biology
Background:
- Nucleosomes are fundamental units of DNA packaging.
- Centromere protein A (CENP-A) is a histone H3 variant essential for kinetochore assembly.
- Previous studies suggested CENP-A nucleosomes have a unique tetrameric hemisomal composition based on reduced height compared to H3 nucleosomes.
Purpose of the Study:
- To investigate the structural composition of CENP-A nucleosomes.
- To determine if CENP-A nucleosomes are inherently different from canonical H3 nucleosomes.
- To clarify the structural basis for CENP-A's role in kinetochore assembly.
Main Methods:
- In vitro assembly of octameric CENP-A nucleosomes.
- Structural analysis comparing CENP-A and H3 nucleosomes.
- Biophysical characterization of nucleosome structure.
Main Results:
- Octameric CENP-A nucleosomes assembled in vitro exhibit reduced heights.
- The reduced height of CENP-A nucleosomes is independent of hemisome formation.
- CENP-A nucleosomes are physically distinct from canonical H3 nucleosomes.
Conclusions:
- The unique structure of CENP-A nucleosomes, characterized by reduced height, is an intrinsic property.
- The findings negate the necessity of invoking hemisomes to explain CENP-A nucleosome structure.
- This structural distinction is key to CENP-A's function in directing kinetochore assembly.
Related Concept Videos
02:30Histone Variants at the Centromere
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 variants are also...
02:54Nucleosome Remodeling
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...
02:38Heterochromatin
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 9th...
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 9th...
01:12The Nucleosome Core Particle
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.
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
02:10The Nucleosome Core Particle
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...
02:33The Nucleosome
DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside the nucleus is astonishing. It is organized into several sequentially higher levels of compaction to 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.
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...