Structural highlights
Function[TBCC_YEAST] Tubulin-folding protein; involved in the early step of the tubulin folding pathway. Publication Abstract from PubMedMicrotubule dynamics and polarity stem from the polymerization of alphass-tubulin heterodimers. Five conserved tubulin cofactors/chaperones and the Arl2 GTPase regulate alpha- and beta-tubulin assembly into heterodimers and maintain the soluble tubulin pool in the cytoplasm, but their physical mechanisms are unknown. Here, we reconstitute a core tubulin chaperone consisting of tubulin cofactors TBCD, TBCE and Arl2, and reveal a cage-like structure for regulating alphabeta-tubulin. Biochemical assays and electron microscopy structures of multiple intermediates show the sequential binding of alphabeta-tubulin dimer followed by tubulin cofactor TBCC onto this chaperone, forming a ternary complex in which Arl2 GTP hydrolysis is activated to alter alphabeta-tubulin conformation. A GTP-state locked Arl2 mutant inhibits ternary complex dissociation in vitro and causes severe defects in microtubule dynamics in vivo. Our studies suggest a revised paradigm for tubulin cofactors and Arl2 functions as a catalytic chaperone that regulates soluble alphabeta-tubulin assembly and maintenance to support microtubule dynamics. Tubulin cofactors and Arl2 are cage-like chaperones that regulate the soluble alphabeta-tubulin pool for microtubule dynamics.,Nithiananatham S, Le S, Seto E, Jia W, Leary J, Corbett KD, Moore JK, Al-Bassam J Elife. 2015 Jul 24;4. doi: 10.7554/eLife.08811. PMID:26208336[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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