BIOGRID CURATED DATA FOR PUBLICATION: The structure of the gamma-tubulin small complex: implications of its architecture and flexibility for microtubule nucleation.

Protein-Protein, Genetic, and Chemical Interactions for Kollman JM (2008):The structure of the gamma-tubulin small complex: implications of its architecture and flexibility for microtubule nucleation. curated by BioGRID (https://thebiogrid.org); ABSTRACT: The gamma-tubulin small complex (gamma-TuSC) is an evolutionarily conserved heterotetramer essential for microtubule nucleation. We have determined the structure of the Saccharomyces cerevisiae gamma-TuSC at 25-A resolution by electron microscopy. gamma-TuSC is Y-shaped, with an elongated body connected to two arms. Gold labeling showed that the two gamma-tubulins are located in lobes at the ends of the arms, and the relative orientations of the other gamma-TuSC components were determined by in vivo FRET. The structures of different subpopulations of gamma-TuSC indicate flexibility in the connection between a mobile arm and the rest of the complex, resulting in variation of the relative positions and orientations of the gamma-tubulins. In all of the structures, the gamma-tubulins are distinctly separated, a configuration incompatible with the microtubule lattice. The separation of the gamma-tubulins in isolated gamma-TuSC likely plays a role in suppressing its intrinsic microtubule-nucleating activity, which is relatively weak until the gamma-TuSC is incorporated into higher order complexes or localized to microtubule-organizing centers. We propose that further movement of the mobile arm is required to bring the gamma-tubulins together in microtubule-like interactions, and provide a template for microtubule growth.

蛋白质-蛋白质、遗传学以及化学相互作用数据集，源自Kollman JM（2008）所著《gamma-微管蛋白小复合体的结构：其架构与柔韧性对微管核化的影响》：该数据集由BioGRID（https://thebiogrid.org）编纂；摘要：gamma-微管蛋白小复合体（gamma-TuSC）作为一种在进化过程中得以保留的异四聚体，对于微管核化至关重要。本研究通过电子显微镜技术，以25埃的分辨率解析了酿酒酵母gamma-TuSC的结构。gamma-TuSC呈Y形，其伸长的主体与两个臂相连。金标记实验表明，两个gamma-微管蛋白位于臂端的叶状结构中，而其他gamma-TuSC组件的相对取向则通过体内FRET技术确定。不同亚群gamma-TuSC的结构表明，移动臂与复合体其他部分的连接具有灵活性，从而导致gamma-微管蛋白的相对位置和取向存在差异。在所有结构中，gamma-微管蛋白均呈现明显分离的状态，这种配置与微管晶格不兼容。在独立的gamma-TuSC中，gamma-微管蛋白的分离可能抑制其固有的微管核化活性，该活性相对较弱，直至gamma-TuSC被整合进更高阶的复合体或定位于微管组织中心。我们提出，需要进一步移动移动臂，以使gamma-微管蛋白在类似微管的结构中进行相互作用，并为微管生长提供模板。