The structural basis of the Talin-KANK1 interaction that coordinates the actin and microtubule cytoskeletons at focal adhesions
The structural basis of the Talin-KANK1 interaction that coordinates the actin and microtubule cytoskeletons at focal adhesions
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Talin-KANK1 相互作用的结构基础，协调粘着斑处的肌动蛋白和微管细胞骨架
DOI：
10.1101/2023.02.23.529676
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Li X
中科院分区：
文献类型：
--
作者：
Li X
细胞与细胞外基质之间的粘附是由异二聚体（αβ）整合素受体介导的，该受体在细胞内与收缩肌动球蛋白机制相关。控制这种联系的蛋白质之一是talin，它将细胞质信号蛋白组织成β-整合素尾部的离散复合体，称为局灶粘连（FAs）。适配蛋白KANK1在FAs区域与talin结合，称为粘附带。在这里，我们采用了一种非共价晶体学伴侣来解析talin-KANK1复合物。该结构揭示了KANK1的talin结合KN区包含一个新的基序，其中β-发夹稳定α-螺旋区，这解释了它与talin R7的特异性相互作用和高亲和力。从结构中发现的KANK1单点突变消除了相互作用，使我们能够检测KANK1在粘附带中的富集。引人注目的是，在表达一种构成活性形式的血管蛋白的细胞中，即使在肌凝蛋白抑制剂存在的情况下，也能保持FA结构的完整，即使在肌动球蛋白张力释放时，KANK1也定位于整个FA结构。我们提出了一个模型，其中肌动球蛋白对talin的作用力消除了在FAs中心的talin结合的KANK1，而将其保留在粘附的外围。
Adhesion between cells and the extracellular matrix is mediated by heterodimeric (αβ) integrin receptors that are intracellularly linked to the contractile actomyosin machinery. One of the proteins that control this link is talin, which organizes cytosolic signalling proteins into discrete complexes on β-integrin tails referred to as focal adhesions (FAs). The adapter protein KANK1 binds to talin in the region of FAs known as the adhesion belt. Here, we adapted a non-covalent crystallographic chaperone to resolve the talin–KANK1 complex. This structure revealed that the talin binding KN region of KANK1 contains a novel motif where a β-hairpin stabilizes the α-helical region, explaining both its specific interaction with talin R7 and high affinity. Single point mutants in KANK1 identified from the structure abolished the interaction and enabled us to examine KANK1 enrichment in the adhesion belt. Strikingly, in cells expressing a constitutively active form of vinculin that keeps the FA structure intact even in the presence of myosin inhibitors, KANK1 localizes throughout the entire FA structure even when actomyosin tension is released. We propose a model whereby actomyosin forces on talin eliminate KANK1 from talin binding in the centre of FAs while retaining it at the adhesion periphery.