Asymmetric Nucleosome Preparation Service

Asymmetric nucleosomes, where the two halves differ in histone composition or modification, are critical for directional epigenetic regulation but have remained elusive to study in vitro. CD BioSciences addresses this gap directly with our specialized asymmetric nucleosome preparation service, providing researchers with homogenous, structurally defined nucleosomes featuring programmed left-right differences. This enables the precise dissection of mechanisms governing reader protein orientation, directional chromatin remodeling, and the establishment of functional specificity within the epigenetic landscape.

Overview of Asymmetric Nucleosome

In vivo, nucleosomes at key regulatory regions, such as active promoters, enhancers, and centromeres, are often asymmetric, featuring different histone variants (e.g., H2A.Z vs. canonical H2A) or distinct post-translational modifications (PTMs) on their two halves. This inherent asymmetry is crucial for directional processes in epigenetics, including polarized transcription, differential recruitment of regulatory complexes, and the establishment of higher-order chromatin architecture. However, conventional nucleosome preparation methods yield only symmetric particles, creating a fundamental technical barrier to studying this biologically critical form of heterogeneity in vitro. Access to well-defined, homogenous asymmetric nucleosomes is therefore essential for dissecting the mechanisms of epigenetic regulation with true molecular precision.

Fig.1 Structure and symmetry of nucleosomes. (Lukasak B J, et al., 2022)

Our Services

At CD BioSciences, we provide a dedicated asymmetric nucleosome preparation service designed to overcome this critical experimental challenge. We employ advanced, stepwise assembly strategies to construct nucleosomes with programmed asymmetry in histone composition, variant identity, or PTM patterns between their two halves. By delivering these uniquely defined molecular tools, we enable researchers to directly interrogate the functional consequences of epigenetic asymmetry, such as directional factor recruitment, cooperative binding, and the mechanistic basis of chromatin's functional specificity, in a controlled biochemical setting.

Comprehensive Solutions for Asymmetric Nucleosome Preparation

Our platform utilizes a stepwise, directional assembly strategy. Instead of random mixing, we first construct two distinct "hemisomes". Each hemi-nucleosome particle comprises half of an H3-H4 tetramer core with a specific H2A-H2B dimer bound to a uniquely designed DNA half-site. These purified hemisomes are then precisely annealed under optimized conditions to form the complete, homogenous asymmetric nucleosome, ensuring controlled heterodimerization and avoiding homodimeric byproducts. Based on this precise methodology, we can prepare a wide range of asymmetric nucleosomes to meet diverse research objectives:

*This table outlines several core asymmetric types that we can implement. Please feel free to contact us if you would like to learn more in detail.

Workflow of Asymmetric Nucleosome Preparation Service

Consultation & Asymmetric Design

We begin with an in-depth discussion to determine the precise asymmetry required for your specific research model, including histone variants, PTMs, and DNA sequences.

Custom DNA Template & Histone Preparation

We design and synthesize specialized DNA constructs (e.g., with staggered ends or unique sequences for directional assembly) and prepare the corresponding, purified histone proteins (including any specified variants or PTMs).

Hemisome Assembly & Purification

Using the custom components, we separately assemble and rigorously purify the two distinct "hemisome" intermediates, each representing one half of the final asymmetric nucleosome.

Controlled Final Assembly

The two purified hemisomes are combined under meticulously optimized annealing conditions to drive the efficient and correct heterodimeric pairing, forming the complete asymmetric nucleosome.

Comprehensive Quality Control

The final product undergoes multi-parameter validation, including native PAGE for homogeneity, mass spectrometry for composition, and analytical ultracentrifugation for structural integrity.

Delivery & Reporting

We deliver the validated, high-purity asymmetric nucleosomes along with a detailed technical dossier containing all assembly parameters, QC data, and functional characterization results.

Diverse Application Scenarios

1. Oriented binding studies of epigenetic "reader" proteins: Determine if they preferentially bind to one specific half of the nucleosome.
2. Directional activity analysis of chromatin remodeling complexes: Investigate whether remodeling initiates from or preferentially acts on a particular side.
3. Mechanistic studies of asymmetric transcription and replication: Use asymmetric nucleosomes as templates to examine how transcriptional or replication machinery processes asymmetric chromatin signals.
4. Molecular basis of higher-order chromatin structure formation: Explore how asymmetric nucleosomes influence nucleosome-nucleosome interactions and fiber folding.

Our Advantages

1. True Bilateral Heterogeneity Control: Achieves precise, pre-programmed differences between the two nucleosomal halves, moving beyond statistical mixtures.
2. High Fidelity in Stoichiometry & Structure: Delivers products with defined composition and consistent, reproducible structures across batches.
3. Unparalleled Physiological Relevance: Provides the most accurate in vitro model to mimic complex chromatin microenvironments found in vivo.
4. Capability to Address Cutting-Edge Questions: Enables direct biochemical investigation into epigenetic asymmetry, a frontier previously difficult to study mechanistically.

The inherent asymmetry of chromatin is a fundamental, yet underexplored, layer of epigenetic regulation. CD BioSciences' dedicated preparation service transforms this biological complexity into a precise, controllable experimental variable. By providing access to these uniquely defined molecular substrates, we empower researchers to directly test hypotheses about epigenetic encoding, remodeling, and higher-order organization with unprecedented biochemical clarity. If you are interested in our services, please feel free to contact us for more details and quotation information of related services.

Reference

1. Lukasak B J, Thompson R E, Mitchener M M, et al. A genetically encoded approach for breaking chromatin symmetry[J]. ACS Central Science, 2022, 8(2): 176-183.