Axial helix rotation as a mechanism for signal regulation inferred from the crystallographic analysis of the E. coli serine chemoreceptor
Axial helix rotation as a mechanism for signal regulation inferred from the crystallographic analysis of the E. coli serine chemoreceptor
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DOI：
10.1016/j.jsb.2014.03.015
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发表时间：
2014-06-01
影响因子：
3
通讯作者：
Lupas, Andrei N.
中科院分区：
文献类型：
--
作者：
Ferris, Hedda U.;Zeth, Kornelius;Lupas, Andrei N.
细菌趋化受体是细长的同质二聚体线圈束，它将在15-20 nm的n端传感器域产生的信号转导到保守的c端信号子域。这种信号转导调节相关激酶的活性，改变鞭毛运动的行为，从而改变细胞运动。信号转导又通过适应子域中特定谷氨酸和谷氨酰胺残基的选择性甲基化和去甲基化来调节。我们已经确定了一个嵌合蛋白的结构，由来自始祖舌菌Af1503的HAMP结构域和大肠杆菌Tsr的甲基接受结构域组成。它显示了一个21 nm的线圈，在两种线圈填充模式之间交替：规范旋钮入孔和互补x-da，一种通过螺旋轴向旋转与规范形式相关的变体形式。将获得的结构与Thermotoga martima化学受体TM1143进行比较，发现它们在适应子域中采用不同的轴向旋转状态。这种构象变化可能是由上游HAMP结构域引起的，并可能调节化学受体对甲基化-去甲基化系统的亲和力。所提出的发现扩展了信号传递到化学感受器的齿轮模型。(C) 2014年作者。Elsevier Inc.出版。
Bacterial chemotaxis receptors are elongated homodimeric coiled-coil bundles, which transduce signals generated in an N-terminal sensor domain across 15-20 nm to a conserved C-terminal signaling subdomain. This signal transduction regulates the activity of associated kinases, altering the behavior of the flagellar motor and hence cell motility. Signaling is in turn modulated by selective methylation and demethylation of specific glutamate and glutamine residues in an adaptation subdomain. We have determined the structure of a chimeric protein, consisting of the HAMP domain from Archaeoglobus fulgidus Af1503 and the methyl-accepting domain of Escherichia colt Tsr. It shows a 21 nm coiled coil that alternates between two coiled-coil packing modes: canonical knobs-into-holes and complementary x-da, a variant form related to the canonical one by axial rotation of the helices. Comparison of the obtained structure to the Thermotoga maritima chemoreceptor TM1143 reveals that they adopt different axial rotation states in their adaptation subdomains. This conformational change is presumably induced by the upstream HAMP domain and may modulate the affinity of the chemoreceptor to the methylation-demethylation system. The presented findings extend the cogwheel model for signal transmission to chemoreceptors. (C) 2014 The Authors. Published by Elsevier Inc.