Sequence-dependent nucleosome nanoscale structure characterized by atomic force microscopy

Area of Science:

• Molecular Biology
• Genomics
• Biophysics

Background:

• DNA sequence is crucial for nucleosome assembly.
• Specific DNA motifs, like the 601 sequence, show high nucleosome specificity.
• How DNA sequence affects DNA wrapping and nucleosome interactions remains unclear.

Purpose of the Study:

• To compare nanoscale properties of nucleosomes assembled on the 601 motif versus random DNA sequences.
• To investigate how DNA sequence influences DNA wrapping and nucleosome positioning.
• To explore the role of DNA sequence in internucleosomal interactions.

Main Methods:

• Atomic Force Microscopy (AFM) was used to measure nucleosome positions and DNA wrapping.
• Nucleosomes were assembled on the 601 motif and random DNA sequences.
• Dinucleosomes were formed on hybrid sequences containing both 601 motif and random DNA.

Main Results:

• Nucleosomes assembled on random sequences showed no positional preference.
• Nucleosomes wrapped the same DNA length on both 601 and random sequences.
• Dinucleosomes on hybrid sequences preferred to position near each other, with one on the 601 motif.

Conclusions:

• DNA sequence influences nucleosome positioning, particularly through internucleosomal interactions.
• The 601 motif plays a significant role in directing dinucleosome positioning.
• Internucleosomal interactions are important for overall nucleosome positioning on DNA.