Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Dev Cell. 2010 Aug 17;19(2):245-58. doi: 10.1016/j.devcel.2010.07.016.
Spatial regulation of microtubule (MT) dynamics contributes to cell polarity and cell division. MT rescue, in which a MT stops shrinking and reinitiates growth, is the least understood aspect of MT dynamics. Cytoplasmic Linker Associated Proteins (CLASPs) are a conserved class of MT-associated proteins that contribute to MT stabilization and rescue in vivo. We show here that the Schizosaccharomyces pombe CLASP, Cls1p, is a homodimer that binds an alphabeta-tubulin heterodimer through conserved TOG-like domains. In vitro, CLASP increases MT rescue frequency, decreases MT catastrophe frequency, and moderately decreases MT disassembly rate. CLASP binds stably to the MT lattice, recruits tubulin, and locally promotes rescues. Mutations in the CLASP TOG domains demonstrate that tubulin binding is critical for its rescue activity. We propose a mechanism for rescue in which CLASP-tubulin dimer complexes bind along the MT lattice and reverse MT depolymerization with their bound tubulin dimer.
微管（MT）动力学的空间调节有助于细胞极性和细胞分裂。MT 挽救，即 MT 停止收缩并重新开始生长，是 MT 动力学中最不为人理解的方面。细胞质连接相关蛋白（CLASPs）是一类保守的 MT 相关蛋白，有助于 MT 的稳定和体内挽救。我们在这里表明，酿酒酵母 CLASP，Cls1p，是一个同源二聚体，通过保守的 TOG 样结构域结合一个alphabeta-微管异二聚体。在体外，CLASP 增加 MT 挽救频率，降低 MT 崩溃频率，并适度降低 MT 解体速率。CLASP 稳定地结合到 MT 晶格上，招募微管，并在局部促进挽救。CLASP TOG 结构域的突变表明，微管结合对于其挽救活性至关重要。我们提出了一种挽救机制，其中 CLASP-微管二聚体复合物沿着 MT 晶格结合，并通过其结合的微管二聚体逆转 MT 解聚。
