ジャーナル: J Cell Sci / 年: 2015 タイトル: The structure of the complex between α-tubulin, TBCE and TBCB reveals a tubulin dimer dissociation mechanism. 著者: Marina Serna / Gerardo Carranza / Jaime Martín-Benito / Robert Janowski / Albert Canals / Miquel Coll / Juan Carlos Zabala / José María Valpuesta / 要旨: Tubulin proteostasis is regulated by a group of molecular chaperones termed tubulin cofactors (TBC). Whereas tubulin heterodimer formation is well-characterized biochemically, its dissociation ...Tubulin proteostasis is regulated by a group of molecular chaperones termed tubulin cofactors (TBC). Whereas tubulin heterodimer formation is well-characterized biochemically, its dissociation pathway is not clearly understood. Here, we carried out biochemical assays to dissect the role of the human TBCE and TBCB chaperones in α-tubulin-β-tubulin dissociation. We used electron microscopy and image processing to determine the three-dimensional structure of the human TBCE, TBCB and α-tubulin (αEB) complex, which is formed upon α-tubulin-β-tubulin heterodimer dissociation by the two chaperones. Docking the atomic structures of domains of these proteins, including the TBCE UBL domain, as we determined by X-ray crystallography, allowed description of the molecular architecture of the αEB complex. We found that heterodimer dissociation is an energy-independent process that takes place through a disruption of the α-tubulin-β-tubulin interface that is caused by a steric interaction between β-tubulin and the TBCE cytoskeleton-associated protein glycine-rich (CAP-Gly) and leucine-rich repeat (LRR) domains. The protruding arrangement of chaperone ubiquitin-like (UBL) domains in the αEB complex suggests that there is a direct interaction of this complex with the proteasome, thus mediating α-tubulin degradation.
温度: 292 K / 手法: 蒸気拡散法, ハンギングドロップ法 / pH: 6.5 詳細: 100 mM Bis Tris pH 6.5 and 43 % (v/v) PEG 400 and 10 mM praseodymium (III) acetate, VAPOR DIFFUSION, HANGING DROP, temperature 292K