CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere

Falk, Samantha J.; Guo, Lucie Y.; Sekulić, Nikolina; Smoak, Evan M.; Mani, Tomoyasu; Logsdon, Glennis A.; Gupta, Kushol; Jansen, Lars; Duyne, Gregory D. Van; Vinogradov, Sergei A.; Lampson, Michael A.; Black, Ben E.

doi:10.1126/science.1259308

Cited by 194 publications

(257 citation statements)

References 56 publications

Supporting

Mentioning

243

Contrasting

Order By: Relevance

“…A potential explanation for the contrast might arise from recent computational modeling experiments which suggest that CENP-A nucleosomes may be adaptable and can shear at the four helix bundles holding together the two pseudo-symmetric halves of the nucleosome 62 . This interpretation is supported, in part, by recent sm-FRET data demonstrating that CENP-A nucleosomal DNA is intrinsically flexible in vitro 63,64 , and that such flexibility is restrained in the presence of kinetochore proteins. For the left-handed canonical nucleosome, extensive studies have shown that the DNA wraps in 1.7 turns a total of 147bp of DNA with a total linking number of approximately -1.0 [45][46][47] .…”

Section: Discussionmentioning

confidence: 74%

The supercoiling state of DNA determines the handedness of both H3 and CENP-A nucleosomes

et al. 2017

View full text Add to dashboard Cite

a Nucleosomes form the unit structure of the genome in eukaryotes, thereby constituting a fundamental tenet of chromatin biology. In canonical nucleosomes, DNA wraps around the histone octamer in a left-handed toroidal ramp. Here, in singlemolecule magnetic tweezers studies of chaperone-assisted nucleosome assembly, we show that the handedness of the DNA wrapping around the nucleosome core is intrinsically ambidextrous, and depends on the pre-assembly supercoiling state of the DNA, i.e., it is not uniquely determined by the octameric histone core. Nucleosomes assembled onto negatively supercoiled DNA are found to exhibit a left-handed conformation, whereas assembly onto positively supercoiled DNA results in right-handed nucleosomes. This intrinsic flexibility to adopt both chiralities is observed both for canonical H3 nucleosomes, and for centromere-specific variant CENP-A nucleosomes. These data support recent advances suggesting an intrinsic adaptability of the nucleosome, and provide insights into how nucleosomes might rapidly reassemble after cellular processes that generate positive supercoiling in vivo. IntroductionIn eukaryotic cells, DNA wraps around histone octamers to form nucleosomes. These particles compact the genome, and mediate accessibility to the underlying DNA, thus regulating major cellular processes like transcription, replication and repair. Hence, the structure of nucleosomes has been the focus of many studies [1][2][3][4][5][6] . As the vast majority of nucleosome structural studies show, DNA wraps around the core histones in a left-handed ramp, with the histones inserting Arginines into the minor groove of DNA once every ~10.4bp. Thus, 147bp of DNA are arranged in 14 segments of a left-handed super-helical ramp around the octamer. Under specialized circumstances, there has been evidence for a minor fraction of nucleosomes existing in right-handed, partial, prenucleosomal, and unfolded forms [8][9][10] . Furthermore, similar to tetrameric nucleosomes found in the archaebacteria [11][12][13] , which can flip between right and left handed states, H3/H4 tetrasomes can adopt a left-or right-handed chirality.Flexibility in the manner in which DNA wraps about the core particle may thus arise from intrinsic adaptability of the H3/H4 interface. Indeed, recent work 18-20 supports early pioneering papers [21][22][23] showing that H3/H4 tetrasomes can inter-convert between the right-and left-handed states. While early work in the chromatin field demonstrated that octameric nucleosomes are preferentially assembled onto negatively supercoiled DNA 24,25 , absorbing the negative DNA plectonemes into the left-handed wrap found in the canonical octamer, more recent work has argued for the presence of "reversomes", transitionary forms used by nucleosomes to switch between handedness 8,26 . Adding to this topological complexity, histone variants such as CENP-A, which replace H3 in centromerespecific nucleosomes, have been correlated with positive supercoils on closed circular mini-plasmids in vivo in yeast, ...

show abstract

Section: Discussionmentioning

confidence: 74%

The supercoiling state of DNA determines the handedness of both H3 and CENP-A nucleosomes

et al. 2017

View full text Add to dashboard Cite

show abstract

“…CENP-C is a key component of most eukaryotic centromeres and links the inner and outer (microtubule binding) components of the kinetochore (Earnshaw 2015). It has been shown that CENP-C colocalizes to CENH3, thus defining active centromere chromatin (Carroll et al 2010;Kato et al 2013;Falk et al 2015). A single CENP-C candidate (RpCENP-C) was identified in an in silico analysis of the pollen mother cell transcriptome of R. pubera.…”

Section: Resultsmentioning

confidence: 99%

Restructuring of Holocentric Centromeres During Meiosis in the Plant Rhynchospora pubera

et al. 2016

View full text Add to dashboard Cite

Centromeres are responsible for the correct segregation of chromosomes during mitosis and meiosis. Holocentric chromosomes, characterized by multiple centromere units along each chromatid, have particular adaptations to ensure regular disjunction during meiosis. Here we show by detecting CENH3, CENP-C, tubulin, and centromeric repeats that holocentromeres may be organized differently in mitosis and meiosis of Rhynchospora pubera. Contrasting to the mitotic linear holocentromere organization, meiotic centromeres show several clusters of centromere units (cluster-holocentromeres) during meiosis I. They accumulate along the poleward surface of bivalents where spindle fibers perpendicularly attach. During meiosis II, the cluster-holocentromeres are mostly present in the midregion of each chromatid. A linear holocentromere organization is restored after meiosis during pollen mitosis. Thus, a not yet described case of a cluster-holocentromere organization, showing a clear centromere restructuration between mitosis and meiosis, was identified in a holocentric organism.KEYWORDS holocentric chromosomes; CENH3; CENP-C; centromere structure/organization; inverted meiosis T HE centromere is the chromosome site responsible for spindle fiber attachment and faithful chromosome segregation during mitosis and meiosis. In general, every eukaryotic chromosome has a centromere on which the kinetochore complex assembles (Cleveland et al. 2003;Burrack and Berman 2012). In most eukaryotes, centromeric nucleosomes contain CENH3 (also known as CENP-A, a histone H3 variant that replaces canonical H3 at the centromere), and usually spans several hundred kilobase pairs often in association with centromere-specific repeats (Steiner and Henikoff 2015).Centromere organization and dynamics vary between mitosis and meiosis (Duro and Marston 2015;Ohkura 2015). During mitosis, sister chromatids are held together by centromere cohesion until metaphase. Simultaneous with the disruption of cohesion, sister chromatids are pulled to opposite poles during anaphase. In contrast, during meiosis, sister centromere cohesion is ensured until metaphase II (Ishiguro and Watanabe 2007). The stepwise regulation of cohesion release during meiosis I (MI) and II (MII) is well studied in organisms with one primary constriction per chromosome (monocentric), ensuring the segregation of homologs at MI followed by the segregation of sister chromatids at MII (Duro and Marston 2015).Contrary to monocentrics, the centromeres of holocentric chromosomes are distributed almost over the entire chromosome length and cohesion occurs along the entire associated sister chromatids (Maddox et al. 2004). Although this does not imply much difference during mitotic divisions, the presence of a holokinetic centromere (holocentromere) imposes obstacles to the dynamics of chromosome segregation in meiosis. Due to their alternative chromosome organization, species with holocentric chromosomes cannot perform the two-step cohesion loss during meiosis typical for monocentric species...

show abstract

“…Our model can account for the recent observation that octameric CENPA nucleosomes reconstituted with 145 bp DNA from a single unit of the 12-unit DXZ1 HOR (with flanking 25-bp linkers) are stabilized by CENPC binding (Falk et al 2015). The DXZ1 dimeric cross-linked particle resembles the Cen1-like particle (which is ∼50× more abundant than DXZ1) (Fig.…”

Section: Cenpt Bridges Adjacent Cenpa Nucleosomesmentioning

confidence: 95%

CENPT bridges adjacent CENPA nucleosomes on young human α-satellite dimers

Thakur

Henikoff

2016

Genome Res.

View full text Add to dashboard Cite

Nucleosomes containing the CenH3 (CENPA or CENP-A) histone variant replace H3 nucleosomes at centromeres to provide a foundation for kinetochore assembly. CENPA nucleosomes are part of the constitutive centromere associated network (CCAN) that forms the inner kinetochore on which outer kinetochore proteins assemble. Two components of the CCAN, CENPC and the histone-fold protein CENPT, provide independent connections from the ∼171-bp centromeric α-satellite repeat units to the outer kinetochore. However, the spatial relationship between CENPA nucleosomes and these two branches remains unclear. To address this issue, we use a base-pair resolution genomic readout of protein-protein interactions, comparative chromatin immunoprecipitation (ChIP) with sequencing, together with sequential ChIP, to infer the in vivo molecular architecture of the human CCAN. In contrast to the currently accepted model in which CENPT associates with H3 nucleosomes, we find that CENPT is centered over the CENPB box between two well-positioned CENPA nucleosomes on the most abundant centromeric young α-satellite dimers and interacts with the CENPB/CENPC complex. Upon cross-linking, the entire CENPA/CENPB/CENPC/CENPT complex is nuclease-protected over an α-satellite dimer that comprises the fundamental unit of centromeric chromatin. We conclude that CENPA/CENPC and CENPT pathways for kinetochore assembly are physically integrated over young α-satellite dimers.

show abstract

CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere

Cited by 194 publications

References 56 publications

The supercoiling state of DNA determines the handedness of both H3 and CENP-A nucleosomes

The supercoiling state of DNA determines the handedness of both H3 and CENP-A nucleosomes

Restructuring of Holocentric Centromeres During Meiosis in the Plant Rhynchospora pubera

CENPT bridges adjacent CENPA nucleosomes on young human α-satellite dimers

Contact Info

Product

Resources

About