Three-dimensional structure of human chromatin accessibility complex hCHRAC by electron microscopy

Area of Science:

• Molecular Biology
• Structural Biology
• Epigenetics

Background:

• ATP-dependent chromatin remodeling complexes are crucial for DNA processes like transcription, replication, and repair.
• Little is known about the detailed structures of these multi-subunit enzymes.
• Understanding their structure is key to understanding their function.

Purpose of the Study:

• To determine the three-dimensional structure of the human chromatin accessibility complex (hCHRAC).
• To provide the first structural insights into the ISWI-family of chromatin remodeling complexes.

Main Methods:

• Single particle reconstruction using negative stain electron microscopy.
• Analysis of the obtained 3D structure.

Main Results:

• The human chromatin accessibility complex (hCHRAC) was visualized in 3D, revealing an asymmetric disk shape (15x10x12nm).
• The structure shows protruding lobes, with four lobes on one side forming a proposed 10nm diameter nucleosome binding surface.
• This detailed structure offers insights into how hCHRAC interacts with nucleosomes.

Conclusions:

• This study presents the first 3D structure of the ISWI-family chromatin remodeling complex, hCHRAC.
• The proposed nucleosome binding surface provides a structural basis for understanding hCHRAC's role in DNA accessibility.
• This structural information is vital for future research on chromatin remodeling mechanisms.