Crosslinkers and Motors Organize Dynamic Microtubules to Form Stable Bipolar Arrays in Fission Yeast

• Published in: Cell Vol. 128; no. 2; pp. 357 - 368
• Main Authors: Janson, Marcel E., Loughlin, Rose, Loïodice, Isabelle, Fu, Chuanhai, Brunner, Damian, Nédélec, François J., Tran, Phong T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26.01.2007
• Subjects: Actin Cytoskeleton - genetics; Actin Cytoskeleton - metabolism; Actin Cytoskeleton - ultrastructure; Binding Sites; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Polarity - physiology; Computer Simulation; Cytoplasmic Streaming - physiology; Cytoskeleton - genetics; Cytoskeleton - metabolism; Cytoskeleton - ultrastructure; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Microtubules - genetics; Microtubules - metabolism; Microtubules - ultrastructure; Mitosis - physiology; Molecular Motor Proteins - genetics; Molecular Motor Proteins - metabolism; Schizosaccharomyces - genetics; Schizosaccharomyces - metabolism; Schizosaccharomyces - ultrastructure; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - metabolism; Spindle Apparatus - genetics; Spindle Apparatus - metabolism; Spindle Apparatus - ultrastructure; Stress, Mechanical
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/j.cell.2006.12.030

Microtubule (MT) nucleation not only occurs from centrosomes, but also in large part from dispersed nucleation sites. The subsequent sorting of short MTs into networks like the mitotic spindle requires molecular motors that laterally slide overlapping MTs and bundling proteins that statically connect MTs. How bundling proteins interfere with MT sliding is unclear. In bipolar MT bundles in fission yeast, we found that the bundler ase1p localized all along the length of antiparallel MTs, whereas the motor klp2p (kinesin-14) accumulated only at MT plus ends. Consequently, sliding forces could only overcome resistant bundling forces for short, newly nucleated MTs, which were transported to their correct position within bundles. Ase1p thus regulated sliding forces based on polarity and overlap length, and computer simulations showed these mechanisms to be sufficient to generate stable bipolar bundles. By combining motor and bundling proteins, cells can thus dynamically organize stable regions of overlap between cytoskeletal filaments.