Architecture of the Dam1 kinetochore ring complex and implications for microtubule-driven assembly and force-coupling mechanisms.
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-A 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.
Wang
Hong-Wei
HW
Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, USA.
Ramey
Vincent H
VH
Westermann
Stefan
S
Leschziner
Andres E
AE
Welburn
Julie P I
JP
Nakajima
Yuko
Y
Drubin
David G
DG
Barnes
Georjana
G
Nogales
Eva
E
D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000648:ultrastructure; D018386:Kinetochores / Q000737:chemistry* / Q000648:ultrastructure; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000648:ultrastructure; D008870:Microtubules / Q000737:chemistry / Q000502:physiology*; D008958:Models, Molecular; D015394:Molecular Structure; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000648:ultrastructure
D018797:Cell Cycle Proteins; C116003:DAM1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins