Sequence periodicities in chicken nucleosome core DNA

Area of Science:

• Structural Biology
• Genetics
• Biochemistry

Background:

• DNA's rotational positioning around histone octamers is crucial for gene regulation.
• Sequence-dependent DNA structural modulations are thought to determine this positioning.

Purpose of the Study:

• To analyze DNA sequences from chicken erythrocyte core particles to understand sequence-dependent DNA structure interactions.
• To correlate DNA sequence variations with DNA bending preferences and rotational orientation around the histone octamer.

Main Methods:

• Analysis of 177 different DNA sequences from chicken erythrocyte core particles.
• Fourier analysis to determine fractional occurrence variations for dinucleotide and trinucleotide arrangements.
• Correlation of sequence content with DNA path and rotational orientation in nucleosome core crystal structures.

Main Results:

• Specific sequence-dependent preferences, including ApApA/TpTpT, ApApT/ApTpT, GpGpC/GpCpC, and ApGpC/GpCpT, correlate with DNA's rotational orientation.
• Minor grooves of certain sequences face inward or outward relative to the histone octamer.
• Long runs of (dA)X(dT) homopolymers are found at the ends of core DNA, away from the dyad, and are excluded from the center.

Conclusions:

• Sequence-specific DNA structural preferences dictate DNA's rotational positioning around histone octamers.
• These findings are applicable to other protein-DNA recognition scenarios involving DNA wrapping.
• The translational positioning of histone octamers is influenced by (dA)X(dT) sequences and potential protein aversion to linker DNA sequences.