Determining the cellular mechanism of de novo centromere establishment in C. elegans embryos

Abstract

De novo centromere formed rapidly on artificial chromosomes (ACs) after injecting DNA in C. elegans germline. The mechanisms underlining nucleation of a de novo centromere from naked DNA is not known. Here we show that the chromatin size of AC is associated with its centromerization, which directly correlates with the length and the structure of injected DNA. We also determined the effect of AT-rich and repetitive sequence features in new centromere formation. The result shows that AT-rich sequence is preferred for new centromere formation. However, highly repetitive sequence has no preference for de novo centromere formation, in compare with non-repetitive “complex” sequence. In addition, we found that a CENP-Ahcp-3 chaperone Rbap46/48Lin-53 is required for de novo centromere formation on ACs, since knock-down of Rbap46/48Lin-53 in embryo cells abolished segregation competence of ACs. This finding reveals that Rbap46/48Lin-53 is the CENP-AHCP-3 loading factor that enables de novo centromere formation on ectopic sites on ACs.