DNA helicase that acts as a tension sensor that associates with catenated DNA which is stretched under tension until it is resolved during anaphase. Functions as ATP-dependent DNA translocase. Can promote Holliday junction branch migration (in vitro). ATP + H2O = ADP + H(+) + phosphate Interacts with PLK1, which phosphorylates it. Both proteins are mutually dependent on each other for correct subcellular localization. Interacts (via N-terminal TPR repeat) with BEND3 (via BEN domains 1 and 3); the interaction is direct. Localizes to kinetochores, inner centromeres and thin threads connecting separating chromosomes even during anaphase. In prometaphase cells, it mostly concentrates in between kinetochores. In metaphase, it localizes to numerous thin threads that stretch between sister kinetochores of the aligned chromosomes and are composed of catenated centromeric DNA. Evolution from inner centromeres to thin threads takes place in response to tension. Resolution of thin threads requires topoisomerase 2-alpha (TOP2A) after anaphase onset. Phosphorylation by PLK1 prevents the association with chromosome arms and restricts its localization to the kinetochore-centromere region. Belongs to the SNF2/RAD54 helicase family.