Dimerization of the CENP‐A assembly factor HJURP is required for centromeric nucleosome deposition |
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| Authors: | Ewelina Zasadzińska Meghan C Barnhart‐Dailey P Henning J L Kuich Daniel R Foltz |
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| Institution: | 1. Department of Biotechnology and Food Sciences, Lodz University of Technology, , Lodz, Poland;2. Department of Biochemistry and Molecular Genetics, University of Virginia Medical School, , Charlottesville, VA, USA;3. Department of Cell Biology, University of Virginia Medical School, , Charlottesville, VA, USA |
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| Abstract: | The epigenetic mark of the centromere is thought to be a unique centromeric nucleosome that contains the histone H3 variant, centromere protein‐A (CENP‐A). The deposition of new centromeric nucleosomes requires the CENP‐A‐specific chromatin assembly factor HJURP (Holliday junction recognition protein). Crystallographic and biochemical data demonstrate that the Scm3‐like domain of HJURP binds a single CENP‐A–histone H4 heterodimer. However, several lines of evidence suggest that HJURP forms an octameric CENP‐A nucleosome. How an octameric CENP‐A nucleosome forms from individual CENP‐A/histone H4 heterodimers is unknown. Here, we show that HJURP forms a homodimer through its C‐terminal domain that includes the second HJURP_C domain. HJURP exists as a dimer in the soluble preassembly complex and at chromatin when new CENP‐A is deposited. Dimerization of HJURP is essential for the deposition of new CENP‐A nucleosomes. The recruitment of HJURP to centromeres occurs independent of dimerization and CENP‐A binding. These data provide a mechanism whereby the CENP‐A pre‐nucleosomal complex achieves assembly of the octameric CENP‐A nucleosome through the dimerization of the CENP‐A chaperone HJURP. |
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| Keywords: | CENP‐A centromere chromatin mitosis nucleosome |
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