Começando do zero: montagem de novo do cinetocoro em vertebrados

segunda-feira, outubro 10, 2011

Have you seen?
The EMBO Journal (2011) 30, 3882 - 3884 

Published online: 6 September 2011

There is an Article (2011) associated with this Have you seen?

Starting from scratch: de novo kinetochore assembly in vertebrates

Sarion R Bowers1 and Barbara G Mellone1
Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA

Correspondence to:

Barbara G Mellone,


Centromeres are epigenetically defined by the presence of the histone H3 variant, CENP-A. Up until now, the question of how CENP-A nucleosomes mediate kinetochore nucleation was poorly understood. In a study just published in Nature, a unique cell-free system was used to demonstrate that in vitro assembled CENP-A chromatin arrays recapitulate the assembly of bona fidekinetochores through the essential C-terminal tail of CENP-A.



In vitro centromere and kinetochore assembly on defined chromatin templates

Annika Guse, Christopher W. Carroll, Ben Moree, Colin J. Fuller
& Aaron F. Straight



Corresponding author

Nature 477, 354–358 (15 September 2011)

Received 18 November 2010 
Accepted 19 July 2011 
Published online 28 August 2011


During cell division, chromosomes are segregated to nascent daughter cells by attaching to the microtubules of the mitotic spindle through the kinetochore. Kinetochores are assembled on a specialized chromatin domain called the centromere, which is characterized by the replacement of nucleosomal histone H3 with the histone H3 variant centromere protein A (CENP-A). CENP-A is essential for centromere and kinetochore formation in all eukaryotes but it is unknown how CENP-A chromatin directs centromere and kinetochore assembly1. Here we generate synthetic CENP-A chromatin that recapitulates essential steps of centromere and kinetochore assembly in vitro. We show that reconstituted CENP-A chromatin when added to cell-free extracts is sufficient for the assembly of centromere and kinetochore proteins, microtubule binding and stabilization, and mitotic checkpoint function. Using chromatin assembled from histone H3/CENP-A chimaeras, we demonstrate that the conserved carboxy terminus of CENP-A is necessary and sufficient for centromere and kinetochore protein recruitment and function but that the CENP-A targeting domain—required for new CENP-A histone assembly2—is not. These data show that two of the primary requirements for accurate chromosome segregation, the assembly of the kinetochore and the propagation of CENP-A chromatin, are specified by different elements in the CENP-A histone. Our unique cell-free system enables complete control and manipulation of the chromatin substrate and thus presents a powerful tool to study centromere and kinetochore assembly.

Subject terms: Biochemistry, Cell biology, Molecular biology


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