Tension sensors reveal how the kinetochore shares its load

At metaphase in mitotic cells, pulling forces at the kinetochore-microtubule interface create tension by stretching the centromeric chromatin between oppositely oriented sister kinetochores. This tension is important for stabilizing the end-on kinetochore microtubule attachment required for proper bi-orientation of sister chromosomes as well as for satisfaction of the Spindle Assembly Checkpoint and entry into anaphase. How force is coupled by proteins to kinetochore microtubules and resisted by centromere stretch is becoming better understood as many of the proteins involved have been identified. Recent application of genetically encoded fluorescent tension sensors within the mechanical linkage between the centromere and kinetochore microtubules are beginning to reveal – from live cell assays – protein specific contributions that are functionally important.

Tension sensors reveal how the kinetochore shares its load: the kinetochore links microtubules (right, green) to the centromere (left, yellow DNA strands wrapped around red histone octamers). By placing FRET biosensors in Ndc80 (blue/yellow and red/green coiled coils), it is possible to study the distribution of force within the kinetochore.

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