Departamento de Química Física Biológica, Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
PLoS One. 2011;6(10):e25912. doi: 10.1371/journal.pone.0025912. Epub 2011 Oct 18.
Human Tubulin Binding Cofactor C (TBCC) is a post-chaperonin involved in the folding and assembly of α- and β-tubulin monomers leading to the release of productive tubulin heterodimers ready to polymerize into microtubules. In this process it collaborates with other cofactors (TBC's A, B, D, and E) and forms a supercomplex with TBCD, β-tubulin, TBCE and α-tubulin. Here, we demonstrate that TBCC depletion results in multipolar spindles and mitotic failure. Accordingly, TBCC is found at the centrosome and is implicated in bipolar spindle formation. We also determine by NMR the structure of the N-terminal domain of TBCC. The TBCC N-terminal domain adopts a spectrin-like fold topology composed of a left-handed 3-stranded α-helix bundle. Remarkably, the 30-residue N-terminal segment of the TBCC N-terminal domain is flexible and disordered in solution. This unstructured region is involved in the interaction with tubulin. Our data lead us to propose a testable model for TBCC N-terminal domain/tubulin recognition in which the highly charged N-terminus as well as residues from the three helices and the loops interact with the acidic hypervariable regions of tubulin monomers.
人微管结合蛋白 C（TBCC）是一种后伴侣素，参与α-和β-微管蛋白单体的折叠和组装，导致有活性的微管蛋白异二聚体释放，准备聚合形成微管。在这个过程中，它与其他辅助因子（TBC 的 A、B、D 和 E）合作，并与 TBCD、β-微管蛋白、TBCE 和 α-微管蛋白形成超复合物。在这里，我们证明 TBCC 的耗竭导致多极纺锤体和有丝分裂失败。因此，TBCC 位于中心体，并且与双极纺锤体的形成有关。我们还通过 NMR 确定了 TBCC N 端结构域的结构。TBCC N 端结构域采用 spectrin 样折叠拓扑结构，由左手 3 股α-螺旋束组成。值得注意的是，TBCC N 端结构域的 30 个残基的 N 端片段在溶液中是灵活的和无定形的。这个无结构区域参与与微管蛋白的相互作用。我们的数据使我们能够提出一个可测试的模型，用于 TBCC N 端结构域/微管蛋白识别，其中带高电荷的 N 端以及来自三个螺旋和环的残基与微管蛋白单体的酸性高变区相互作用。
