Hanrahan Jessie, Snyder Michael
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Mol Cell. 2003 Sep;12(3):663-73. doi: 10.1016/j.molcel.2003.08.006.
The assembly of cytoskeletal structures is coupled to other cellular processes. We have studied the molecular mechanism by which assembly of the yeast septin cytoskeleton is monitored and coordinated with cell cycle progression by analyzing a key regulatory protein kinase, Hsl1, that becomes activated only when the septin cytoskeleton is properly assembled. We first identified a regulatory region of Hsl1 that physically associates with the kinase domain and found that it performs an autoinhibitory function both in vivo and in vitro. Several septin binding domains lie near and overlap the inhibitory domain; these are important for Hsl1 function, and binding of two septins, Cdc11 and Cdc12, relieves the autoinhibition imposed by the kinase inhibitory domain in vitro. Our results suggest that binding to multiple septins activates Hsl1 kinase activity, thereby promoting cell cycle progression. The high conservation of Hsl1 indicates that similar mechanisms may monitor cytoskeletal organization in other eukaryotes.
细胞骨架结构的组装与其他细胞过程相关联。我们通过分析一种关键的调节蛋白激酶Hsl1，研究了酵母隔膜蛋白细胞骨架组装被监测并与细胞周期进程协调的分子机制，该激酶仅在隔膜蛋白细胞骨架正确组装时才被激活。我们首先鉴定了Hsl1的一个调节区域，它与激酶结构域发生物理结合，并发现它在体内和体外均具有自抑制功能。几个隔膜蛋白结合结构域位于抑制结构域附近并与之重叠；这些结构域对Hsl1的功能很重要，并且两种隔膜蛋白Cdc11和Cdc12的结合可在体外解除激酶抑制结构域施加的自抑制作用。我们的结果表明，与多种隔膜蛋白的结合可激活Hsl1激酶活性，从而促进细胞周期进程。Hsl1的高度保守性表明，类似的机制可能在其他真核生物中监测细胞骨架的组织情况。
