Linked in: formation and regulation of microtubule attachments during chromosome segregation

Abstract

Accurate segregation of the replicated genome during cell division depends on dynamic attachments formed between chromosomes and the microtubule polymers of the spindle. Here we review recent advances in mechanistic analysis of microtubule attachment formation and regulation.

Figure 1. Different Resolution Views of Kinetochore Architecture

(A) A slice from an EM tomogram of plus ends embedded in the outer kinetochore (top; courtesy of R. McIntosh) and a thin cross-sectional view of a cold-stable kinetochore fiber (courtesy of C. Rieder; ref. 20). The schematic on the left highlights a plate-like architecture at the kinetochore evident in older EM studies whose existence has come under debate following the development of new EM preservation methods [see ref. 5]. (B) Schematic of the RWD domain that recurs in multiple kinetochore proteins. The domain is always present in 2 copies – either as a heterodimer or as a homodimer. The structure of the Spc24/25 heterodimer from the Ndc80 complex, the first kinetochore components found to harbor this domain, is shown on the right (PDB 2FTX); Spc24 has a minimal RWD domain—the other kinetochore protein listed below harbor different insertions in the loop indicated by the arrow. (C) Negative stain EM images of purified native yeast kinetochore-like particles. Images of particles on their own and bound to microtubule ends are shown (courtesy of S. Biggins; ref 19].