Chromosome size and origin as determinants of the level of CENP-A incorporation into human centromeres.
We have expressed an EGFP-CENP-A fusion protein in human cells in order to quantitate the level of CENP-A incorporated into normal and variant human centromeres. The results revealed a 3.2-fold difference in the level of CENP-A incorporation into alpha-satellite repeat DNA-based centromeres, with the Y centromere showing the lowest level of all normal human chromosomes. Identification of individual chromosomes revealed a statistically significant, though not absolute, correlation between chromosome size and CENP-A incorporation. Analysis of three independent neocentromeres revealed a significantly reduced level of CENP-A compared to normal centromeres. Truncation of a neocentric marker chromosome to produce a minichromosome further reduced CENP-A levels, indicating a remodelling of centromeric chromatin. These results suggest a role for increased CENP-A incorporation in the faithful segregation of larger chromosomes and support a model of centromere evolution in which neocentromeres represent ancestral centromeres that, through adaptive evolution, acquire satellite repeats to facilitate the incorporation of higher numbers of CENP-A containing nucleosomes, thereby facilitating the assembly of larger kinetochore structures.
Irvine
Danielle V
DV
The Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville 3052, Australia.
Amor
David J
DJ
Perry
Jo
J
Sirvent
Nicolas
N
Pedeutour
Florence
F
Choo
K H Andy
KH
Saffery
Richard
R
D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002503:Centromere / Q000378:metabolism*; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D002877:Chromosomes, Human / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D008297:Male; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins