Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text (PDF, 426K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Wells, W. A. Search for Related Content PubMed Articles by Wells, W. A. Social Bookmarking                            What's this?

Kinetochores hold on with a ring

DASH forms a collar around microtubules. HARRISON/MACMILLAN

A complex that links a budding yeast kinetochore to a microtubule (MT) forms a ring around the MT, based on structures from two groups. The ring may help kinetochores to keep hold of an MT, even as the MT shrinks towards the spindle pole during anaphase.

Stephen Harrison (Harvard Medical School, Boston, MA) and Peter Sorger (MIT, Cambridge, MA) are hoping to analyze the structure of the 60 or more yeast kinetochore proteins one subcomplex at a time. The current success with the 10-protein DASH complex, Harrison says, "came about on a dare to see if [first author JJ Miranda] could coexpress the whole thing in E. coli." Happily, the bold experiment worked, the purified complex bound MTs, and the electron micrographs clearly showed rings of DASH complex encircling an MT.

The ring structure immediately suggests a mechanistic possibility. "A major way in which evolution has made entities processive is by making rings," says Harrison. In this case, the outward splaying of MT protofilaments as the end of an MT falls apart should keep the ring on the intact section of the MT. This would effectively translocate the ring and thus the attached kinetochore towards the pole-attached end of the shrinking MT. Indeed, Stefan Westermann and Georjana Barnes (University of California, Berkeley, CA) used Miranda's construct to not only come up with a similar structure, but also to gain evidence for mobility of DASH rings along MTs.

References:

Miranda, J.L., et al. 2005. Nat. Struc. Mol. Biol. doi:10.1038/nsmb896.

Westermann, S., et al. 2005. Mol. Cell. 17:277–290.[CrossRef][Medline]

William A. Wells

wellsw{at}rockefeller.edu

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This Article Full Text (PDF, 426K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Wells, W. A. Search for Related Content PubMed Articles by Wells, W. A. Social Bookmarking                            What's this?