Structure of the Single-lobe Myosin Light Chain C in Complex with the Light Chain-binding Domains of Myosin-1C Provides Insights into Divergent IQ Motif Recognition *
Structure of the Single-lobe Myosin Light Chain C in Complex with the Light Chain-binding Domains of Myosin-1C Provides Insights into Divergent IQ Motif Recognition *
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DOI：
10.1074/jbc.m116.746313
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
D. Langelaan;Janine Liburd;Yidai Yang;Emily Miller;S. Chitayat;Scott W. Crawley;G. Côté;Steven P. Smith
中科院分区：
文献类型：
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作者：
D. Langelaan;Janine Liburd;Yidai Yang;Emily Miller;S. Chitayat;Scott W. Crawley;G. Côté;Steven P. Smith
肌球蛋白轻链是 1 类肌球蛋白的关键调节因子，通常包含两个结构域，钙调蛋白就是典型的例子。它们在肌球蛋白颈部区域结合 IQ 基序，并放大运动域的构象变化。最近鉴定出一条单叶轻链，肌球蛋白轻链 C (MlcC)，并显示其特异性结合盘基网柄菌 myosin-1C 的两个连续不同的 IQ 基序。为了提供这种相互作用的分子基础，确定了 apo-MlcC 和 2:1 MlcC·myosin-1C 颈复合物的结构。 MlcC 的两个非功能性 EF 手基序堆积在一起形成球状四螺旋束，该四螺旋束打开以暴露中央疏水沟，该沟与不同的 IQ1 和 IQ2 基序的 N 端部分相互作用。 MlcC 的 N 端和 C 端区域形成关键接触，有助于其与肌球蛋白-1C 不同 IQ 基序的特异性相互作用，这些接触偏离了钙调蛋白-IQ 识别的传统模式。
Myosin light chains are key regulators of class 1 myosins and typically comprise two domains, with calmodulin being the archetypal example. They bind IQ motifs within the myosin neck region and amplify conformational changes in the motor domain. A single lobe light chain, myosin light chain C (MlcC), was recently identified and shown to specifically bind to two sequentially divergent IQ motifs of the Dictyostelium myosin-1C. To provide a molecular basis of this interaction, the structures of apo-MlcC and a 2:1 MlcC·myosin-1C neck complex were determined. The two non-functional EF-hand motifs of MlcC pack together to form a globular four-helix bundle that opens up to expose a central hydrophobic groove, which interacts with the N-terminal portion of the divergent IQ1 and IQ2 motifs. The N- and C-terminal regions of MlcC make critical contacts that contribute to its specific interactions with the myosin-1C divergent IQ motifs, which are contacts that deviate from the traditional mode of calmodulin-IQ recognition.