Kinetochore-microtubule error correction is driven by differentially regulated interaction modes.

Chromosome segregation requires precise alignment of sister kinetochores with microtubules from opposite spindle poles. This alignment, known as bi-orientation, is essential for accurate cell division. Aurora B kinase plays a central role in correcting faulty attachments by destabilizing incorrect connections. However, it remains unclear how new attachments can form while error correction is ongoing. Prior research has shown that aurora B activity is necessary for attachment disruption, but the mechanisms allowing simultaneous attachment formation are not well understood. This gap motivated the current study to investigate the specific roles of different attachment modes in error correction. The study aimed to clarify how lateral and end-on kinetochore-microtubule interactions are regulated. Understanding these mechanisms is crucial for explaining how bi-orientation is achieved and maintained. The researchers sought to determine whether different attachment types respond differently to aurora B activity. Their findings could help resolve a long-standing question in cell division biology.

The study aimed to uncover how aurora B kinase selectively disrupts incorrect kinetochore-microtubule attachments while allowing new ones to form. The researchers focused on the distinction between lateral and end-on attachment modes. They hypothesized that these two attachment types might be regulated differently by aurora B. By identifying the specific targets of aurora B activity, the team sought to explain the mechanism of error correction. Their goal was to determine whether lateral attachments are resistant to aurora B, enabling new connections to form. The study also aimed to clarify how end-on attachments are selectively destabilized. Understanding this process is key to explaining how bi-orientation is established. The researchers wanted to reveal the molecular basis for this selective regulation.

The researchers used budding yeast as a model system to study kinetochore-microtubule interactions. They employed fluorescence microscopy to visualize attachment dynamics in live cells. To track aurora B activity, they used phospho-specific antibodies. The team also performed genetic manipulations to alter kinetochore components. They tested the effects of these manipulations on attachment stability and error correction. By comparing lateral and end-on attachment behaviors, they identified differences in regulation. The researchers used biochemical assays to study the phosphorylation of Dam1 and Ndc80. Their approach combined live-cell imaging with molecular and genetic techniques.

The study found that lateral kinetochore-microtubule attachments are not affected by aurora B activity. In contrast, end-on attachments are destabilized by this kinase. This suggests that lateral attachments can form without interference during error correction. The researchers observed that lateral attachments are converted to end-on attachments over time. If the end-on attachment is incorrect, it is released by aurora B activity. This cycle continues until bi-orientation is achieved. Aurora B specifically targets the Dam1 and Ndc80 components for phosphorylation. The results show that phospho-regulation of these proteins drives end-on attachment disruption.

The findings suggest that aurora B selectively disrupts end-on attachments while allowing lateral attachments to form. This mechanism enables error correction without blocking new attachment attempts. The study supports the idea that lateral and end-on attachments are regulated differently. The researchers propose that lateral attachments act as a buffer during error correction. Their results explain how bi-orientation can be established through repeated attempts. The study highlights the importance of phospho-regulation in this process. Aurora B activity on Dam1 and Ndc80 appears to be central to this mechanism. The authors suggest that this selective regulation is key to accurate chromosome segregation.