Access

Article

Nature Structural & Molecular Biology 14, 721–726 (1 August 2007) | doi:10.1038/nsmb1274

Architecture of the Dam1 kinetochore ring complex and implications for microtubule-driven assembly and force-coupling mechanisms

Hong-Wei Wang , Vincent H Ramey , Stefan Westermann , Andres E Leschziner , Julie P I Welburn , Yuko Nakajima , David G Drubin , Georjana Barnes & Eva Nogales

The Dam1 kinetochore complex is essential for chromosome segregation in budding yeast. This ten-protein complex self-assembles around microtubules, forming ring-like structures that move with depolymerizing microtubule ends, a mechanism with implications for cellular function. Here we used EM-based single-particle and helical analyses to define the architecture of the Dam1 complex at 30-|[Aring]| resolution and the self-assembly mechanism. Ring oligomerization seems to be facilitated by a conformational change upon binding to microtubules, suggesting that the Dam1 ring is not preformed, but self-assembles around kinetochore microtubules. The C terminus of the Dam1p protein, where most of the Aurora kinase Ipl1 phosphorylation sites reside, is in a strategic location to affect oligomerization and interactions with the microtubule. One of Ipl1's roles might be to fine-tune the coupling of the microtubule interaction with the conformational change required for oligomerization, with phosphorylation resulting in ring breakdown.