Abstract
Centromeres are the attachment points between the genome and the cytoskeleton: centromeres bind to kinetochores, which in turn bind to spindles and move chromosomes. Paradoxically, the DNA sequence of centromeres has little or no role in perpetuating kinetochores. As such they are striking examples of genetic information being transmitted in a manner that is independent of DNA sequence (epigenetically). It has been found that RNA transcribed from centromeres remains bound within the kinetochore region, and this local population of RNA is thought to be part of the epigenetic marking system. Here we carried out a genetic and biochemical study of maize CENPC, a key inner kinetochore protein. We show that DNA binding is conferred by a localized region 122 amino acids long, and that the DNA-binding reaction is exquisitely sensitive to single-stranded RNA. Long, single-stranded nucleic acids strongly promote the binding of CENPC to DNA, and the types of RNAs that stabilize DNA binding match in size and character the RNAs present on kinetochores in vivo. Removal or replacement of the binding module with HIV integrase binding domain causes a partial delocalization of CENPC in vivo. The data suggest that centromeric RNA helps to recruit CENPC to the inner kinetochore by altering its DNA binding characteristics.
Highlights
Centromeres are important features of the genome that connect chromosomes to spindles
Drosophila Centromere protein C (CENPC) is required to target Centromeric Histone H3 (CENH3), but CENH3 is required to target CENPC [20,22]. These data suggest that kinetochore replication is a self reinforcing process whereby key inner kinetochore proteins such as CENPC work in concert with CENH3 to replicate the content and position of centromeres
We address the issue of how genetic information is passed from one generation to the without the involvement of specific DNA sequences
Summary
Centromeres are important features of the genome that connect chromosomes to spindles. In the absence of CENH3, all other kinetochore proteins fail to localize and chromosomes cannot move on the spindle [10,11,12,13]. In addition several proteins that require CENH3 for localization serve to target new CENH3 [18,19,20]. One such protein is Centromere protein C (CENPC), a DNA binding protein that has a key role in centromere recognition and maintenance [21]. These data suggest that kinetochore replication is a self reinforcing process whereby key inner kinetochore proteins such as CENPC work in concert with CENH3 to replicate the content and position of centromeres
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