Publication Date:
2017-02-22
Description:
The centromere is a specialized chromosomal structure that dictates kinetochore assembly and, thus, is essential for accurate chromosome segregation. Centromere identity is determined epigenetically by the presence of a centromere-specific histone H3 variant, CENP-A, that replaces canonical H3 in centromeric chromatin. Here, we discuss recent work by Roulland et al. that identifies structural elements of the nucleosome as essential determinants of centromere function. In particular, CENP-A nucleosomes have flexible DNA ends due to the short αN helix of CENP-A. The higher flexibility of the DNA ends of centromeric nucleosomes impairs binding of linker histones H1, while it facilitates binding of other essential centromeric proteins, such as CENP-C, and is required for mitotic fidelity. This work extends previous observations indicating that the differential structural properties of CENP-A nucleosomes are on the basis of its contribution to centromere identity and function. Here, we discuss the implications of this work and the questions arising from it. Recent work by Roulland et al. shows that the short αN helix of CENP-A is responsible for the “open” conformation of CENP-A nucleosomes. This conformation impairs histone H1 binding, being required for centromere/kinetochore assembly and mitotic fidelity. The contribution of additional CENP-A structural features to centromere function is also reviewed.
Print ISSN:
0265-9247
Electronic ISSN:
1521-1878
Topics:
Biology
,
Medicine
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