Publication Date:
2010-07-16
Description:
Microtubules are nucleated in vivo by gamma-tubulin complexes. The 300-kDa gamma-tubulin small complex (gamma-TuSC), consisting of two molecules of gamma-tubulin and one copy each of the accessory proteins Spc97 and Spc98, is the conserved, essential core of the microtubule nucleating machinery. In metazoa multiple gamma-TuSCs assemble with other proteins into gamma-tubulin ring complexes (gamma-TuRCs). The structure of gamma-TuRC indicated that it functions as a microtubule template. Because each gamma-TuSC contains two molecules of gamma-tubulin, it was assumed that the gamma-TuRC-specific proteins are required to organize gamma-TuSCs to match 13-fold microtubule symmetry. Here we show that Saccharomyces cerevisiae gamma-TuSC forms rings even in the absence of other gamma-TuRC components. The yeast adaptor protein Spc110 stabilizes the rings into extended filaments and is required for oligomer formation under physiological buffer conditions. The 8-A cryo-electron microscopic reconstruction of the filament reveals 13 gamma-tubulins per turn, matching microtubule symmetry, with plus ends exposed for interaction with microtubules, implying that one turn of the filament constitutes a microtubule template. The domain structures of Spc97 and Spc98 suggest functions for conserved sequence motifs, with implications for the gamma-TuRC-specific proteins. The gamma-TuSC filaments nucleate microtubules at a low level, and the structure provides a strong hypothesis for how nucleation is regulated, converting this less active form to a potent nucleator.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921000/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921000/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kollman, Justin M -- Polka, Jessica K -- Zelter, Alex -- Davis, Trisha N -- Agard, David A -- F32 GM078790-03/GM/NIGMS NIH HHS/ -- R01 GM031627/GM/NIGMS NIH HHS/ -- R01 GM031627-27/GM/NIGMS NIH HHS/ -- R01 GM040506/GM/NIGMS NIH HHS/ -- R01 GM040506-21/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2010 Aug 12;466(7308):879-82. doi: 10.1038/nature09207. Epub 2010 Jul 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, and Keck Advanced Microscopy Center, University of California, San Francisco, San Francisco, California 94158, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20631709" target="_blank"〉PubMed〈/a〉
Keywords:
Buffers
;
Cryoelectron Microscopy
;
Cytoskeletal Proteins/chemistry/metabolism
;
Microtubule-Associated Proteins/chemistry/metabolism
;
Microtubules/*chemistry/metabolism/*ultrastructure
;
Models, Biological
;
Models, Molecular
;
Multiprotein Complexes/chemistry/metabolism/ultrastructure
;
Nuclear Proteins/chemistry/metabolism
;
Saccharomyces cerevisiae/chemistry/*cytology/*ultrastructure
;
Saccharomyces cerevisiae Proteins/chemistry/metabolism
;
Tubulin/*chemistry/metabolism/*ultrastructure
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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