%0 Journal Article
%T Assembly of Drosophila Centromeric Chromatin Proteins during Mitosis
%A Barbara G. Mellone
%A Kathryn J. Grive equal contributor
%A Vladimir Shteyn equal contributor
%A Sarion R. Bowers
%A Isaac Oderberg
%A Gary H. Karpen
%J PLOS Genetics
%D 2011
%I Public Library of Science (PLoS)
%R 10.1371/journal.pgen.1002068
%X Semi-conservative segregation of nucleosomes to sister chromatids during DNA replication creates gaps that must be filled by new nucleosome assembly. We analyzed the cell-cycle timing of centromeric chromatin assembly in Drosophila, which contains the H3 variant CID (CENP-A in humans), as well as CENP-C and CAL1, which are required for CID localization. Pulse-chase experiments show that CID and CENP-C levels decrease by 50% at each cell division, as predicted for semi-conservative segregation and inheritance, whereas CAL1 displays higher turnover. Quench-chase-pulse experiments demonstrate that there is a significant lag between replication and replenishment of centromeric chromatin. Surprisingly, new CID is recruited to centromeres in metaphase, by a mechanism that does not require an intact mitotic spindle, but does require proteasome activity. Interestingly, new CAL1 is recruited to centromeres before CID in prophase. Furthermore, CAL1, but not CENP-C, is found in complex with pre-nucleosomal CID. Finally, CENP-C displays yet a different pattern of incorporation, during both interphase and mitosis. The unusual timing of CID recruitment and unique dynamics of CAL1 identify a distinct centromere assembly pathway in Drosophila and suggest that CAL1 is a key regulator of centromere propagation.
%U http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002068