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Mps1 and Ipl1/Aurora B Act Sequentially to Correctly Orient Chromosomes on the Meiotic Spindle of Budding Yeast

Science  01 Mar 2013:
Vol. 339, Issue 6123, pp. 1071-1074
DOI: 10.1126/science.1232518

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Mastering Meiosis

Two conserved kinases (Ipl1/Aurora B and Mps1) are known to be critical for correct chromosome orientation on the spindle during meiosis, but their roles and relationships in controlling chromosome segregation are unclear. Working in yeast, Meyer et al. (p. 1071, published online 31 January) monitored chromosomes as they go through the steps of properly attaching to the spindle microtubules and dissected the roles of the two kinases in chromosome pairing, orientation, and segregation.

Abstract

The conserved kinases Mps1 and Ipl1/Aurora B are critical for enabling chromosomes to attach to microtubules so that partner chromosomes will be segregated correctly from each other, but the precise roles of these kinases have been unclear. We imaged live yeast cells to elucidate the stages of chromosome-microtubule interactions and their regulation by Ipl1 and Mps1 through meiosis I. Ipl1 was found to release kinetochore-microtubule (kMT) associations after meiotic entry, liberating chromosomes to begin homologous pairing. Surprisingly, most chromosome pairs began their spindle interactions with incorrect kMT attachments. Ipl1 released these improper connections, whereas Mps1 triggered the formation of new force-generating microtubule attachments. This microtubule release and reattachment cycle could prevent catastrophic chromosome segregation errors in meiosis.

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