Cdc48 and its co-factor Ufd1 segregate CENP-A from centromeric chromatin and can induce chromosome elimination in the fission yeastSchizosaccharomyces pombe

Abstract

AbstractCENP-A, a variant of histone H3, determines the identity of the centromere, a chromosome locus at which a microtubule attachment site termed kinetochore is assembled. Because the position and size of the centromere and its number per chromosome must be maintained for the faithful segregation of chromosomes, the distribution of CENP-A is strictly regulated. In this study, we have aimed to understand mechanisms to regulate the distribution of CENP-A by a genetic approach in the fission yeastSchizosaccharomyces pombe. A mutant of theufd1+gene (ufd1-73) encoding a cofactor of Cdc48 ATPase is sensitive to CENP-A expressed at a high level and allows mislocalization of CENP-A. ChIP analysis has revealed that the level of CENP-A in centromeric chromatin is increased in theufd1-73mutant even when CENP-A is expressed at a normal level. A preexisting mutant of thecdc48+gene (cdc48-353) phenocopies theufd1-73mutant. We have also shown that Cdc48 and Ufd1 proteins physically interact with centromeric chromatin. Finally, Cdc48 ATPase with Ufd1 artificially recruited to the centromere of a mini-chromosome (Ch16) induce a loss of CENP-A fromCh16, resulting in an increased rate of chromosome loss. It appears that Cdc48 ATPase, together with its cofactor Ufd1 segregates excess CENP-A from chromatin, likely in a direct manner, to maintain proper distribution of CENP-A. This mechanism may play an important role in centromere disassembly, a process to eliminate CENP-A massively to inactivate the kinetochore function during development, differentiation, and stress response in other organisms.Significance statementMaintaining the proper distribution of CENP-A is crucial for centromere identity. This process involves accurate positioning of CENP-A and removal of excess CENP-A from chromatin. The Cdc48-Ufd1 complex is essential for this regulation as it acts as a segregase that directly eliminates surplus CENP-A from chromatin. These findings have therapeutic significance as targeting the Cdc48 complex can potentially correct abnormal karyotypes in disomic embryos and prevent trisomic disorders like Down syndrome. This research advances our understanding of centromeric chromatin regulation and its potential therapeutic applications.