HAMP domain conformers that propagate opposite signals in bacterial chemoreceptors.
HAMP domain conformers that propagate opposite signals in bacterial chemoreceptors.
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DOI：
10.1371/journal.pbio.1001479
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发表时间：
2013
期刊：
影响因子：
9.8
通讯作者：
Crane BR
中科院分区：
文献类型：
--
作者：
Airola MV;Sukomon N;Samanta D;Borbat PP;Freed JH;Watts KJ;Crane BR
细胞表面受体如何将信号传递到细胞内？这项研究解决了如何通过细菌化学感受器的HAMP结构域的信号中继发生，使它们在两种构象状态之间切换。HAMP结构域是细菌、真核生物和古细菌的> 26，000种受体中的信号中继模块，其介导涉及趋化性、发病机制和生物膜形成的过程。我们确定了两个HAMP构象区别于四到两个螺旋包装过渡的C-末端，在细菌化学感受器发送相反的信号。信号锁定突变体的晶体结构建立了观察到的结构与功能的关系。脉冲偶极电子自旋共振波谱自旋标记的可溶性受体在细胞中的活性验证，晶体学定义的HAMP构象保持在受体中，并相应地影响下游结构域的结构和活性。HR 2是设置HAMP构象并产生抑制信号的关键残基，HR 2的突变使HAMP结构和受体输出转变为活化状态。另一种HR 2变体显示相对于配体的反向响应，并证明了“开”和“关”构象之间的精细能量平衡。在膜近端HAMP结构域中发现的DExG基序被证明对细胞外配体的应答至关重要。我们的研究结果直接关联在体内信号与HAMP的结构，稳定性和动力学建立一个全面的模型HAMP介导的信号中继，巩固现有的观点构象信号如何在受体中传播。此外，我们已经开发出一种合理的手段来操纵HAMP的结构和功能，可能证明有用的工程细菌的趋性反应。生物信号转导的一个中心问题是细胞表面受体如何将来自外部世界的信号穿过细胞膜并进入细胞本身。在细菌和低等真核生物中，这种受体由负责特定功能的单个模块组成（例如，传感、继电器或输出）。HAMP结构域在许多受体中充当信号中继模块，物理桥接输入和输出组件并在它们之间传递信号。通过晶体学，生物物理学，光谱学和功能研究的组合，我们能够关联两个结构上定义的HAMP构象状态与功能的“开”和“关”的信号在细菌化学感受器，从而解决的机制，HAMPs可以中继信息。这两种状态在结构和动力学上都不同，并且似乎在下游输出模块上强制执行它们的属性。化学感受器允许细菌以灵敏度和动态范围跟踪化学梯度;我们进一步表明，对化学引诱物的反应关键取决于靠近膜的特定HAMP残基。最后，基于开关机制，我们设计并产生了一个反向信号HAMP结构域，它提供了一种新的工具来工程细菌的反应，并可能是特别有利的修复工作，指导细菌对化学物质，通常是驱虫剂。
How do cell-surface receptors transmit signals into cells? This study resolves how signal relay occurs through the HAMP domains of bacterial chemoreceptors by causing them to switch between two conformational states. HAMP domains are signal relay modules in >26,000 receptors of bacteria, eukaryotes, and archaea that mediate processes involved in chemotaxis, pathogenesis, and biofilm formation. We identify two HAMP conformations distinguished by a four- to two-helix packing transition at the C-termini that send opposing signals in bacterial chemoreceptors. Crystal structures of signal-locked mutants establish the observed structure-to-function relationships. Pulsed dipolar electron spin resonance spectroscopy of spin-labeled soluble receptors active in cells verify that the crystallographically defined HAMP conformers are maintained in the receptors and influence the structure and activity of downstream domains accordingly. Mutation of HR2, a key residue for setting the HAMP conformation and generating an inhibitory signal, shifts HAMP structure and receptor output to an activating state. Another HR2 variant displays an inverted response with respect to ligand and demonstrates the fine energetic balance between “on” and “off” conformers. A DExG motif found in membrane proximal HAMP domains is shown to be critical for responses to extracellular ligand. Our findings directly correlate in vivo signaling with HAMP structure, stability, and dynamics to establish a comprehensive model for HAMP-mediated signal relay that consolidates existing views on how conformational signals propagate in receptors. Moreover, we have developed a rational means to manipulate HAMP structure and function that may prove useful in the engineering of bacterial taxis responses. A central question in biological signal transduction is how cell-surface receptors transmit signals from the outside world across cell membranes and into the cells themselves. In bacteria and lower eukaryotes such receptors are composed of individual modules responsible for specific functions (e.g., sensing, relay, or output). HAMP domains act as the signal relay modules in many receptors, physically bridging input and output components and transferring signals between them. Through a combination of crystallographic, biophysical, spectroscopic, and functional studies we are able to associate two structurally defined HAMP conformational states with functional “on” and “off” signals in bacterial chemoreceptors, and thereby resolve the mechanism by which HAMPs can relay information. The two states differ in both their structure and dynamics and appear to enforce their properties on downstream output modules. Chemoreceptors allow bacteria to track chemical gradients with exquisite sensitivity and dynamic range; we further show that the response to chemoattractant depends critically on specific HAMP residues close to the membrane. Finally, based on the switching mechanism, we design and generate an inverse signaling HAMP domain that provides a new tool to engineer bacterial responses and may be especially advantageous in remediation efforts for directing bacteria towards chemicals that are normally repellants.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
2.2
作者：
Chiang, YW;Borbat, PP;Freed, JH
通讯作者：
Freed, JH
DOI：
10.1107/s0907444909052925
发表时间：
2010-02
期刊：
Acta crystallographica. Section D, Biological crystallography
影响因子：
--
作者：
Adams PD;Afonine PV;Bunkóczi G;Chen VB;Davis IW;Echols N;Headd JJ;Hung LW;Kapral GJ;Grosse-Kunstleve RW;McCoy AJ;Moriarty NW;Oeffner R;Read RJ;Richardson DC;Richardson JS;Terwilliger TC;Zwart PH
通讯作者：
Zwart PH
影响因子：
5.4
作者：
Hazelbauer, Gerald L.;Lai, Wing-Cheung
通讯作者：
Lai, Wing-Cheung
DOI：
10.1107/s0907444998003254
发表时间：
1998-09-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
影响因子：
--
作者：
Brunger, AT;Adams, PD;Warren, GL
通讯作者：
Warren, GL