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Mol. Cell. Biol., Aug 1995, 4009-4020, Vol 15, No. 8
D Kipling, AR Mitchell, H Masumoto, HE Wilson, L Nicol and HJ Cooke
Minor satellite DNA, found at Mus musculus centromeres, is not present in
the genome of the Asian mouse Mus caroli. This repetitive sequence family
is speculated to have a role in centromere function by providing an array
of binding sites for the centromere-associated protein CENP-B. The apparent
absence of CENP-B binding sites in the M. caroli genome poses a major
challenge to this hypothesis. Here we describe two abundant satellite DNA
sequences present at M. caroli centromeres. These satellites are organized
as tandem repeat arrays, over 1 Mb in size, of either 60- or 79-bp
monomers. All autosomes carry both satellites and small amounts of a
sequence related to the M. musculus major satellite. The Y chromosome
contains small amounts of both major satellite and the 60-bp satellite,
whereas the X chromosome carries only major satellite sequences. M. caroli
chromosomes segregate in M. caroli x M. musculus interspecific hybrid cell
lines, indicating that the two sets of chromosomes can interact with the
same mitotic spindle. Using a polyclonal CENP-B antiserum, we demonstrate
that M. caroli centromeres can bind murine CENP-B in such an interspecific
cell line, despite the absence of canonical 17-bp CENP-B binding sites in
the M. caroli genome. Sequence analysis of the 79-bp M. caroli satellite
reveals a 17-bp motif that contains all nine bases previously shown to be
necessary for in vitro binding of CENP-B. This M. caroli motif binds CENP-B
from HeLa cell nuclear extract in vitro, as indicated by gel mobility shift
analysis. We therefore suggest that this motif also causes CENP-B to
associate with M. caroli centromeres in vivo. Despite the sequence
differences, M. caroli presents a third, novel mammalian centromeric
sequence producing an array of binding sites for CENP-B.
Copyright © 1995, American Society for Microbiology
CENP-B binds a novel centromeric sequence in the Asian mouse Mus caroli
MRC Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom.
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