Molecular architecture of the augmin complex.

Clinton A Gabel, Zhuang Li, Andrew G DeMarco, Ziguo Zhang, Jing Yang, Mark C Hall, David Barford, Leifu Chang

Nature communications 2022 Sep 16

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Accurate segregation of chromosomes during mitosis depends on the correct assembly of the mitotic spindle, a bipolar structure composed mainly of microtubules. The augmin complex, or homologous to augmin subunits (HAUS) complex, is an eight-subunit protein complex required for building robust mitotic spindles in metazoa. Augmin increases microtubule density within the spindle by recruiting the γ-tubulin ring complex (γ-TuRC) to pre-existing microtubules and nucleating branching microtubules. Here, we elucidate the molecular architecture of augmin by single particle cryo-electron microscopy (cryo-EM), computational methods, and crosslinking mass spectrometry (CLMS). Augmin's highly flexible structure contains a V-shaped head and a filamentous tail, with the head existing in either extended or contracted conformational states. Our work highlights how cryo-EM, complemented by computational advances and CLMS, can elucidate the structure of a challenging protein complex and provides insights into the function of augmin in mediating microtubule branching nucleation. © 2022. The Author(s).

Citation

Clinton A Gabel, Zhuang Li, Andrew G DeMarco, Ziguo Zhang, Jing Yang, Mark C Hall, David Barford, Leifu Chang. Molecular architecture of the augmin complex. Nature communications. 2022 Sep 16;13(1):5449