Cryo-EM structures of CENP-A nucleosomes isolated from human cells.

Cryo-EM reveals that native human CENP-A nucleosomes form octamers with distinct homotypic and heterotypic structures, crucial for centromere identity.

• Why it matters: Understanding the native structure of CENP-A nucleosomes is essential for elucidating how epigenetic marks maintain centromere function and chromosome stability in human cells.
• What they did: Using cryogenic electron microscopy combined with chromatin immunoprecipitation, the study determined the structures of two types of CENP-A nucleosomes directly from human cells, without crosslinking.
• The result: Both nucleosome types assemble as histone octamers wrapping DNA in a left-handed superhelix, with preserved CENP-A-specific features, advancing our knowledge of centromeric chromatin architecture.