Hertzer Kathleen M, Walczak Claire E
Medical Sciences, Indiana University, Bloomington, Indiana 47405, USA.
Cell Cycle. 2008 Sep 1;7(17):2727-37. doi: 10.4161/cc.7.17.6590. Epub 2008 Sep 12.
MCAK is a Kinesin-13 that depolymerizes microtubules (MTs) and regulates MT dynamics. We used subtilisin-treated MTs (MTs lacking the C-termini of alpha- and beta-tubulin) and alternative tubulin substrates to study which structural and geometrical features of the MT are critical for MCAK activity. We found that removal of the C-termini significantly decreased the efficiency of MCAK-induced depolymerization, which was not due to a reduction of end-specific binding. We also found that depolymerization of SMTs led to an increase in the stabilization of curved oligomeric tubulin products. Using alternative tubulin substrates with different geometries, we found that MCAK depolymerized parallel and anti-parallel tubulin sheets. However, MCAK did not depolymerize tubulin rings regardless of the presence or absence of the tubulin C-termini. We propose that localization of MCAK to the ends of MTs is independent of tubulin C-termini, that MCAK stabilizes a curved conformation at the end of the MT, and that efficient release of this complex is dependent on the presence of the C-termini of tubulin.
MCAK是一种驱动蛋白-13，可使微管（MTs）解聚并调节MT动力学。我们使用枯草杆菌蛋白酶处理的MTs（缺乏α-和β-微管蛋白C末端的MTs）和替代微管蛋白底物来研究MT的哪些结构和几何特征对MCAK活性至关重要。我们发现去除C末端显著降低了MCAK诱导解聚的效率，这并非由于末端特异性结合的减少。我们还发现SMTs的解聚导致弯曲的寡聚微管蛋白产物的稳定性增加。使用具有不同几何形状的替代微管蛋白底物，我们发现MCAK使平行和反平行的微管蛋白片层解聚。然而，无论微管蛋白C末端是否存在，MCAK都不会使微管蛋白环解聚。我们提出，MCAK定位于MT末端独立于微管蛋白C末端，MCAK在MT末端稳定弯曲构象，并且这种复合物的有效释放依赖于微管蛋白C末端的存在。
