Kinetochore–microtubule error correction for biorientation: lessons from yeast

Abstract

Accurate chromosome segregation in mitosis relies on sister kinetochores forming stable attachments to microtubules (MTs) extending from opposite spindle poles and establishing biorientation. To achieve this, erroneous kinetochore–MT interactions must be resolved through a process called error correction, which dissolves improper kinetochore–MT attachment and allows new interactions until biorientation is achieved. The Aurora B kinase plays key roles in driving error correction by phosphorylating Dam1 and Ndc80 complexes, while Mps1 kinase, Stu2 MT polymerase and phosphatases also regulate this process. Once biorientation is formed, tension is applied to kinetochore–MT interaction, stabilizing it. In this review article, we discuss the mechanisms of kinetochore–MT interaction, error correction and biorientation. We focus mainly on recent insights from budding yeast, where the attachment of a single MT to a single kinetochore during biorientation simplifies the analysis of error correction mechanisms.

Molecular basis for condensin enrichment at pericentromeres

“…Centromere-loaded cohesin extrudes a loop on either side to shape the ~10kb pericentromere, and convergent genes flanking centromeres set the position of the pericentromere borders by acting as barriers to loop extrusion and sites of sister chromatid cohesion 20 . This loop-based structure at pericentromeres provides a platform for surveillance mechanisms that direct and sense the establishment of biorientation 23 . The pericentromeric adaptor protein, Shugoshin, Sgo1, acts downstream of cohesin and plays a key role in this process.…”