From the Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei 230027, China and.
the Key Laboratory of Structural Biology, Hefei Science Center of CAS, Chinese Academy of Sciences, Hefei 230027, China.
J Biol Chem. 2018 Jan 12;293(2):557-566. doi: 10.1074/jbc.M117.817494. Epub 2017 Nov 28.
A well-controlled microtubule organization is essential for intracellular transport, cytoskeleton maintenance, and cell development. KN motif and ankyrin repeat domain-containing protein 1 (KANK1), a member of KANK family, recruits kinesin family member 21A (KIF21A) to the cell cortex to control microtubule growth via its C-terminal ankyrin domain. However, how the KANK1 ankyrin domain recognizes KIF21A and whether other KANK proteins can also bind KIF21A remain unknown. Here, using a combination of structural, site-directed mutagenesis, and biochemical studies, we found that a stretch of ∼22 amino acids in KIF21A is sufficient for binding to KANK1 and its close homolog KANK2. We further solved the complex structure of the KIF21A peptide with either the KANK1 ankyrin domain or the KANK2 ankyrin domain. In each complex, KIF21A is recognized by two distinct pockets of the ankyrin domain and adopts helical conformations upon binding to the ankyrin domain. The elucidated KANK structures may advance our understanding of the role of KANK1 as a scaffolding molecule in controlling microtubule growth at the cell periphery.
微管组织的良好控制对于细胞内运输、细胞骨架维持和细胞发育至关重要。KN 基序和锚蛋白重复结构域蛋白 1（KANK1）是 KANK 家族的一员，通过其 C 端锚蛋白结构域将驱动蛋白家族成员 21A（KIF21A）募集到细胞膜，从而控制微管生长。然而，KANK1 锚蛋白结构域如何识别 KIF21A，以及其他 KANK 蛋白是否也能与 KIF21A 结合，目前仍不清楚。在这里，我们通过结构、定点突变和生化研究的组合，发现 KIF21A 中的一段约 22 个氨基酸足以与 KANK1 及其密切同源物 KANK2 结合。我们进一步解析了 KIF21A 肽与 KANK1 锚蛋白结构域或 KANK2 锚蛋白结构域复合物的结构。在每个复合物中，KIF21A 被锚蛋白结构域的两个不同口袋识别，并在与锚蛋白结构域结合时采用螺旋构象。阐明的 KANK 结构可能有助于我们理解 KANK1 作为细胞外围微管生长的支架分子的作用。
