Aiken Jayne, Sept David, Costanzo Michael, Boone Charles, Cooper John A, Moore Jeffrey K
Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
Department of Biomedical Engineering and Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA.
Curr Biol. 2014 Jun 16;24(12):1295-1303. doi: 10.1016/j.cub.2014.03.078. Epub 2014 May 15.
Microtubules (MTs) support diverse transport and force generation processes in cells. Both α- and β-tubulin proteins possess carboxy-terminal tail regions (CTTs) that are negatively charged, intrinsically disordered, and project from the MT surface where they interact with motors and other proteins. Although CTTs are presumed to play important roles in MT networks, these roles have not been determined in vivo.
We examined the function of CTTs in vivo by using a systematic collection of mutants in budding yeast. We find that CTTs are not essential; however, loss of either α- or β-CTT sensitizes cells to MT-destabilizing drugs. β-CTT, but not α-CTT, regulates MT dynamics by increasing frequencies of catastrophe and rescue events. In addition, β-CTT is critical for the assembly of the mitotic spindle and its elongation during anaphase. We use genome-wide genetic interaction screens to identify roles for α- and β-CTTs, including a specific role for β-CTT in supporting kinesin-5/Cin8. Our genetic screens also identified novel interactions with pathways not related to canonical MT functions.
We conclude that α- and β-CTTs play important and largely discrete roles in MT networks. β-CTT promotes MT dynamics. β-CTT also regulates force generation in the mitotic spindle by supporting kinesin-5/Cin8 and dampening dynein. Our genetic screens identify links between α- and β-CTT and additional cellular pathways and suggest novel functions.
微管（MTs）在细胞中支持多种运输和力产生过程。α-微管蛋白和β-微管蛋白都具有带负电荷、内在无序的羧基末端尾部区域（CTTs），这些区域从微管表面伸出，在那里它们与马达蛋白和其他蛋白质相互作用。尽管推测CTTs在微管网络中发挥重要作用，但这些作用尚未在体内得到确定。
我们通过对芽殖酵母中的突变体进行系统收集来研究CTTs在体内的功能。我们发现CTTs并非必不可少；然而，α-CTT或β-CTT的缺失会使细胞对微管破坏药物敏感。β-CTT而非α-CTT通过增加灾难和拯救事件的频率来调节微管动力学。此外，β-CTT对于有丝分裂纺锤体的组装及其在后期的伸长至关重要。我们使用全基因组遗传相互作用筛选来确定α-CTT和β-CTT的作用，包括β-CTT在支持驱动蛋白-5/Cin8方面的特定作用。我们的遗传筛选还确定了与非典型微管功能相关途径的新相互作用。
我们得出结论，α-CTT和β-CTT在微管网络中发挥重要且基本不同的作用。β-CTT促进微管动力学。β-CTT还通过支持驱动蛋白-5/Cin8和抑制动力蛋白来调节有丝分裂纺锤体中的力产生。我们的遗传筛选确定了α-CTT和β-CTT与其他细胞途径之间的联系，并暗示了新的功能。
