Modulation of MICAL Monooxygenase Activity by its Calponin Homology Domain: Structural and Mechanistic Insights.
Modulation of MICAL Monooxygenase Activity by its Calponin Homology Domain: Structural and Mechanistic Insights.
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DOI：
10.1038/srep22176
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发表时间：
2016-03-03
影响因子：
4.6
通讯作者：
Bianchet MA
中科院分区：
文献类型：
--
作者：
Alqassim SS;Urquiza M;Borgnia E;Nagib M;Amzel LM;Bianchet MA
MICALs（Molecule Interacting with CasL）是一种保守的多结构域酶，在神经发育、内吞作用和凋亡中对细胞骨架重组至关重要。在这些酶中，2型钙调蛋白同源（CH）结构域总是跟随N-末端单加氧酶（MO）结构域。虽然CH结构域是MICAL-1细胞定位和肌动蛋白相关功能所必需的，但其对MICAL活性调节对肌动蛋白的作用仍不清楚。在这里，我们提出了一个片段的MICAL-1包含的MO和CH域的结构，确定由X-射线晶体学和小角散射，以及动力学实验，旨在探测的贡献的CH域的肌动蛋白修饰活性。我们的研究结果表明，CH结构域，这是松散的连接到MO结构域的一个灵活的连接器，是远离催化位点，耦合F-肌动蛋白的氧化还原活性的增强MICALMO-CH通过一个合作机制，涉及相邻的绑定分子之间的反式相互作用。在调节肌动蛋白组装/拆卸动力学的其他蛋白质中也观察到结合协同性，例如ADF/Cofilins。
MICALs (Molecule Interacting with CasL) are conserved multidomain enzymes essential for cytoskeletal reorganization in nerve development, endocytosis, and apoptosis. In these enzymes, a type-2 calponin homology (CH) domain always follows an N-terminal monooxygenase (MO) domain. Although the CH domain is required for MICAL-1 cellular localization and actin-associated function, its contribution to the modulation of MICAL activity towards actin remains unclear. Here, we present the structure of a fragment of MICAL-1 containing the MO and the CH domains—determined by X-ray crystallography and small angle scattering—as well as kinetics experiments designed to probe the contribution of the CH domain to the actin-modification activity. Our results suggest that the CH domain, which is loosely connected to the MO domain by a flexible linker and is far away from the catalytic site, couples F-actin to the enhancement of redox activity of MICALMO-CH by a cooperative mechanism involving a trans interaction between adjacently bound molecules. Binding cooperativity is also observed in other proteins regulating actin assembly/disassembly dynamics, such as ADF/Cofilins.