Figure: Structure of the centromere histone complex containing two chains of CENPA (red) and two copies of its close binding partner, histone H4 (blue). (Image: Ben E. Black, University of Pennsylvania School of Medicine)

Epigenetics

Ben Black group (University of Pennsylvania)

Epigenetic abnormalities and their effects on the ~10¹¹ daily human cell divisions can lead to abnormalities in chromosomes resulting in many types of disorders, from cancer to Down syndrome. Ben Black and his colleagues, utilizing two synchrotron sources (one of them GM/CA @ APS), defined the structure of a key molecule -- a subnucleosomal heterotetramer, human (CENP-A-H4)₂ -- that plays a central role in DNA replication. CENP-A-H4 is a histone tetramer found at centromeres. Without this molecule, entire chromosomes can be lost during cell division. This work is a major advance in understanding the molecules driving human genetic inheritance.

Citation: Sekulic N, Bassett EA, Rogers DJ, Black BE. The structure of (CENP-A-H4)₂ reveals physical features that mark centromeres. Nature. 2010 Sep 16; 467: 347-351. doi:10.1038/nature09323.