A Tale of Two CENPCs: Centromere Localization of KINETOCHORE NULL2 and CENP-C.

Although we have long known the repetitive nature of the DNA in plant and animal centromeres of plant and animals and have identified hundreds of kinetochore proteins, closing the mechanistic gap between the centromereDNAand thekinetochoreprotein complex has remained a challenge. Much research has focused on the centromeric histone cenH3, as cenH3-containing nucleosomes may provide a mark for formation of anactivecentromere (reviewedinLermontova et al., 2015). Placement of cenH3 in nucleosomes at the centromere involves initiation, deposition, andmaintenance steps, andmultiple factors affect cenH3 localization and formationof theactive centromere. For example, the kinetochore component CENP-C interacts with cenH3 nucleosomes through its conserved CENPC motif (Kato et al., 2013) and functions in the placement of cenH3 in additional nucleosomes. CENP-CalsointeractswithKINETOCHORE NULL2 (KNL2), and Lermontova et al. (2013) previously found that Arabidopsis thaliana KNL2 localizes to the centromere and acts upstream of cenH3 deposition. The knl2 knockout mutants showed defects in