Long-range oscillation in a periodic DNA sequence motif may influence nucleosome array formation.

Area of Science:

• Chromatin biology
• Genomics
• Molecular genetics

Background:

• Nucleosome arrays form the fundamental structure of chromatin.
• The relationship between DNA sequence and higher-order chromatin structure is not fully understood.
• Previous studies suggest DNA sequence can influence nucleosome positioning.

Purpose of the Study:

• To investigate the link between DNA sequence and nucleosome array formation in mouse liver chromatin.
• To identify DNA sequence features that dictate regular nucleosome packaging.
• To compare chromatin structure in gene-specific loci versus bulk chromatin.

Main Methods:

• Experimental examination of nucleosome array formation in mouse liver chromatin regions.
• Computational analysis of corresponding genomic DNA sequences.
• In vitro chromatin assembly experiments.
• Genome-wide survey for nucleosome-ordering signals.

Main Results:

• The mouse adenosine deaminase (MADA) gene locus exhibits highly regular nucleosome arrays with a shortened repeat, predictable from its DNA sequence.
• A nucleosome-ordering signal, characterized by oscillations in the VWG motif, was identified in <10% of surveyed genomic windows, with MADA showing a strong signal.
• The mouse odorant receptor (MOR) locus, lacking such signals, displayed nucleosome arrays similar to bulk chromatin, representing ~40% of surveyed DNA.
• Experimental results confirmed that DNA sequences computationally similar to MADA or MOR loci produced corresponding nucleosome array patterns.

Conclusions:

• Computationally predictable information within DNA sequences can significantly influence nucleosome array formation in animal tissues.
• Specific DNA sequence motifs act as nucleosome-ordering signals, dictating chromatin structure.
• The MADA and MOR loci serve as examples of distinct DNA sequence-driven chromatin organization patterns.