Davies Tim, Kodera Noriyuki, Kaminski Schierle Gabriele S, Rees Eric, Erdelyi Miklos, Kaminski Clemens F, Ando Toshio, Mishima Masanori
Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom.
Department of Physics and Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, Japan.
PLoS Biol. 2015 Apr 13;13(4):e1002121. doi: 10.1371/journal.pbio.1002121. eCollection 2015 Apr.
Centralspindlin, a constitutive 2:2 heterotetramer of MKLP1 (a kinesin-6) and the non-motor subunit CYK4, plays important roles in cytokinesis. It is crucial for the formation of central spindle microtubule bundle structure. Its accumulation at the central antiparallel overlap zone is key for recruitment and regulation of downstream cytokinesis factors and for stable anchoring of the plasma membrane at the midbody. Both MKLP1 and CYK4 are required for efficient microtubule bundling. However, the mechanism by which CYK4 contributes to this is unclear. Here we performed structural and functional analyses of centralspindlin using high-speed atomic force microscopy, Fӧrster resonance energy transfer analysis, and in vitro reconstitution. Our data reveal that CYK4 binds to a globular mass in the atypically long MKLP1 neck domain between the catalytic core and the coiled coil and thereby reconfigures the two motor domains in the MKLP1 dimer to be suitable for antiparallel microtubule bundling. Our work provides insights into the microtubule bundling during cytokinesis and into the working mechanisms of the kinesins with non-canonical neck structures.
中心纺锤体微管蛋白复合物由MKLP1（一种驱动蛋白-6）和非运动亚基CYK4组成一个稳定的2:2异源四聚体，在胞质分裂中发挥重要作用。它对于中心纺锤体微管束结构的形成至关重要。其在中心反平行重叠区的积累是招募和调节下游胞质分裂因子以及将质膜稳定锚定在中体的关键。MKLP1和CYK4对于有效的微管束形成都是必需的。然而，CYK4促成这一过程的机制尚不清楚。在这里，我们使用高速原子力显微镜、荧光共振能量转移分析和体外重组对中心纺锤体微管蛋白复合物进行了结构和功能分析。我们的数据表明，CYK4与催化核心和卷曲螺旋之间非典型长的MKLP1颈部结构域中的一个球状结构结合，从而重新配置MKLP1二聚体中的两个运动结构域，使其适合反平行微管束形成。我们的工作为胞质分裂过程中的微管束形成以及具有非典型颈部结构的驱动蛋白的工作机制提供了见解。
