5vjc
TOG-tubulin binding specificity promotes microtubule dynamics and mitotic spindle formation
Structural highlights
FunctionMSPS_DROME Binds to the plus end of microtubules and regulates microtubule dynamics and microtubule organization. Promotes cytoplasmic microtubule nucleation and elongation. May act as a microtubule antipause factor that rapidly catalyzes the transition from pause to either growth or shrinkage. Involved in mitotic spindle elongation. Involved in the establishment of cell polarity and mitotic spindle orientation in neuroblasts. Required for maintaining the bipolarity of acentrosomal meiotic spindles; the function is dependent on tacc and involves ncd. Involved in oocyte microtubule cytoskeleton organization and bicoid mRNA localization. Seems to be involved in elongation of kinetochore-derived microtubule fibers.[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedXMAP215, CLASP, and Crescerin use arrayed tubulin-binding tumor overexpressed gene (TOG) domains to modulate microtubule dynamics. We hypothesized that TOGs have distinct architectures and tubulin-binding properties that underlie each family's ability to promote microtubule polymerization or pause. As a model, we investigated the pentameric TOG array of a Drosophila melanogaster XMAP215 member, Msps. We found that Msps TOGs have distinct architectures that bind either free or polymerized tubulin, and that a polarized array drives microtubule polymerization. An engineered TOG1-2-5 array fully supported Msps-dependent microtubule polymerase activity. Requisite for this activity was a TOG5-specific N-terminal HEAT repeat that engaged microtubule lattice-incorporated tubulin. TOG5-microtubule binding maintained mitotic spindle formation as deleting or mutating TOG5 compromised spindle architecture and increased the mitotic index. Mad2 knockdown released the spindle assembly checkpoint triggered when TOG5-microtubule binding was compromised, indicating that TOG5 is essential for spindle function. Our results reveal a TOG5-specific role in mitotic fidelity and support our hypothesis that architecturally distinct TOGs arranged in a sequence-specific order underlie TOG array microtubule regulator activity. TOG-tubulin binding specificity promotes microtubule dynamics and mitotic spindle formation.,Byrnes AE, Slep KC J Cell Biol. 2017 Jun 5;216(6):1641-1657. doi: 10.1083/jcb.201610090. Epub 2017, May 16. PMID:28512144[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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