Article

Centromere assembly requires the direct recognition of CENP-A nucleosomes by CENP-N

Department of Biochemistry, Stanford University School of Medicine, Beckman Center, Palo Alto, CA 94503-5307, USA.
Nature Cell Biology (Impact Factor: 19.68). 07/2009; 11(7):896-902. DOI: 10.1038/ncb1899
Source: PubMed

ABSTRACT

Centromeres are specialized chromosomal domains that direct kinetochore assembly during mitosis. CENP-A (centromere protein A), a histone H3-variant present exclusively in centromeric nucleosomes, is thought to function as an epigenetic mark that specifies centromere identity. Here we identify the essential centromere protein CENP-N as the first protein to selectively bind CENP-A nucleosomes but not H3 nucleosomes. CENP-N bound CENP-A nucleosomes in a DNA sequence-independent manner, but did not bind soluble CENP-A-H4 tetramers. Mutations in CENP-N that reduced its affinity for CENP-A nucleosomes caused defects in CENP-N localization and had dominant effects on the recruitment of CENP-H, CENP-I and CENP-K to centromeres. Depletion of CENP-N using siRNA (short interfering RNA) led to similar centromere assembly defects and resulted in reduced assembly of nascent CENP-A into centromeric chromatin. These data suggest that CENP-N interprets the information encoded within CENP-A nucleosomes and recruits other proteins to centromeric chromatin that are required for centromere function and propagation.

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Available from: Lars Jansen, Feb 24, 2014
    • "om the diagonal in Fig . 3 B and a lower correlation in the matrix of Fig . 3 C . This suggests that CENP - N is not always associated with CENP - H / - I / - K / - M . The profile plots for CENP - N and CENP - L are nearly identical , consistent with studies that these proteins form a heterodimeric complex when they are loaded on chromo - somes ( Carroll et al . , 2009 ; Hinshaw and Harrison , 2013 ) . Both proteins were significantly depleted from chromo - somes isolated from CENP - H OFF / - I OFF / - K OFF / - M OFF / - N OFF cells . Their reduction was , however , more modest in chro - mosomes from other CCAN mutant cells , i . e . , CENP - C OFF / - S KO / - O KO / - R KO ( Fig . 4 B ) ."
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    • "Because reducing H4K20me1 levels at centromeres causes mislocalization of CENP-H and CENP-T, this modification might help render CENP-A chromatin competent for kinetochore assembly (Figure 6). Other histone modifications of CENP-A nucleosomes or of centromeric nucleosomes containing canonical H3 might also be involved in formation of functional centromeric chromatin, possibly by influencing interactions with other kinetochore proteins such as CENP-C or CENP-N, which bind to CENP-A nucleosomes concentrated in centromeres (Carroll et al., 2009; Guse et al., 2011; Kato et al., 2013). "
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