Nanobioscience Constellation, College of Nanoscale Science and Engineering, University at Albany, State University of New York (SUNY), Albany, NY, USA.
Cell Cycle. 2013 Mar 1;12(5):842-8. doi: 10.4161/cc.23822. Epub 2013 Feb 6.
The γ-tubulin ring complex (γ-TuRC) is a key part of microtubule-organizing centers (MTOCs) that control microtubule polarity, organization and dynamics in eukaryotes. Understanding regulatory mechanisms of γ-TuRC function is of fundamental importance, as this complex is central to many cellular processes, including chromosome segregation, fertility, neural development, T-cell cytotoxicity and respiration. The fission yeast microtubule motor kinesin-14 Pkl1 regulates mitosis by binding to the γ-tubulin small complex (γ-TuSC), a subunit of γ-TuRC. Here we investigate the binding mechanism of Pkl1 to γ-TuSC and its functional consequences using genetics, biochemistry, peptide assays and cell biology approaches in vivo and in vitro. We identify two critical elements in the Tail domain of Pkl1 that mediate γ-TuSC binding and trigger release of γ-tubulin from γ-TuRC. Such action disrupts the MTOC and results in failed mitotic spindle assembly. This study is the first demonstration that a motor protein directly affects the structural composition of the γ-TuRC, and we provide details of this mechanism that may be of broad biological importance.
γ-微管蛋白环复合物（γ-TuRC）是微管组织中心（MTOC）的关键组成部分，控制着真核生物中微管的极性、组织和动力学。了解 γ-TuRC 功能的调节机制至关重要，因为该复合物是许多细胞过程的核心，包括染色体分离、生育能力、神经发育、T 细胞细胞毒性和呼吸作用。裂殖酵母微管马达蛋白 kinesin-14 Pkl1 通过与 γ-微管蛋白小复合物（γ-TuSC）结合来调节有丝分裂，γ-TuSC 是 γ-TuRC 的一个亚基。在这里，我们使用遗传学、生物化学、肽测定以及体内和体外的细胞生物学方法，研究了 Pkl1 与 γ-TuSC 的结合机制及其功能后果。我们确定了 Pkl1 的尾部结构域中的两个关键元素，这些元素介导了 γ-TuSC 的结合，并触发了 γ-微管蛋白从 γ-TuRC 中的释放。这种作用会破坏 MTOC 并导致有丝分裂纺锤体装配失败。这项研究首次证明了一种马达蛋白可以直接影响 γ-TuRC 的结构组成，并且我们提供了该机制的详细信息，这可能具有广泛的生物学意义。
