Disruption of the standard kinetochore in holocentricCuscutaspecies

Abstract

AbstractSegregation of chromosomes depends on the centromere. Most species are monocentric, with the centromere restricted to a single region per chromosome. In some organisms, monocentric organization changed to holocentric, in which the centromere activity is distributed over the entire chromosome length. However, the causes and consequences of this transition are poorly understood. Here, we show that the transition in the genusCuscutawas associated with dramatic changes in the kinetochore, a protein complex that mediates the attachment of chromosomes to microtubules. We found that in holocentricCuscutaspecies the KNL2 genes were lost; the CENP-C, KNL1, and ZWINT1 genes were truncated; the centromeric localization of CENH3, CENP-C, KNL1, MIS12, and NDC80 proteins was disrupted; and the spindle assembly checkpoint (SAC) was degenerated. Our results demonstrate that holocentricCuscutaspecies lost the ability to form a standard kinetochore and do not employ SAC to control the attachment of microtubules to chromosomes.