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演題：Microtubule nucleation by gamma-tubulin complexes: mechanisms and evolution

演者：Elmar Schiebel 博士（Zentrum fuer Molekulare  Biologie, Universitaet Heidelberg, Germany）

日時：2014年 11月28日（金）14:45-15:30

場所：吉田講堂

連絡先：広田　亨（内線5251）

抄録：　

Microtubules assemble through the polymerization of tubulin, a heterodimer of alpha- and beta-tubulin. De novo formation of microtubules is initiated by complexes that contain the tubulin family member gamma-tubulin. The yeast gamma-tubulin assembles together with the conserved subunits Spc97/GCP2 and Spc98/GCP3 into the tetrameric small gamma-tubulin complex (gamma-TuSC). Data from the Agard laboratory have shown that gamma-TuSC can assemble in vitro under low salt conditions into rings and spirals. This behavior supports the template model according to which a gamma-tubulin ring functions as template for the assembly of microtubules. We have measured the subunit composition of single microtubule nucleation sites in vivo and could show that the number of gamma-tubulin molecules at the microtubule minus end is consistent with the template model. We further have shown that the gamma-TuSC receptor Spc110 at the yeast microtubule organizing centre, the spindle pole body (SPB), facilitates gamma-TuSC oligomerization upon recruitment of gamma-TuSC to the SPB. Phosphorylation of Spc110 by Cdk1 and Mps1 kinases regulates this process. Conserved regions within gamma-TuSC receptors allowed us to study the evolution of the microtubule nucleation system. In collaboration with Profs. Hideo Kigoshi, Yoshio Hayashi, and

Takeo Usui, we have developed a gamma-tubulin specific inhibitor. I will discuss these findings and the implications for the function of gamma-tubulin.

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