Hexameric rings of the scaffolding protein CheW enhance response sensitivity and cooperativity in Escherichia coli chemoreceptor arrays.
Hexameric rings of the scaffolding protein CheW enhance response sensitivity and cooperativity in Escherichia coli chemoreceptor arrays.
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DOI：
10.1126/scisignal.abj1737
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发表时间：
2022-01-25
影响因子：
7.3
通讯作者：
Parkinson, John S.
中科院分区：
文献类型：
--
作者：
Pinas, German E.;DeSantis, Michael D.;Cassidy, C. Keith;Parkinson, John S.
大肠杆菌化学感受器阵列是一种超分子组装体，其显示出非凡的信号传导能力，其机制基础仅部分了解。该阵列具有保守的结构，其中跨膜受体，组织为二聚体的三聚体，在其细胞质尖端由交替的激酶CheA和支架蛋白CheW分子的六聚体环（CheA-CheW环）连接。这些分子间的相互作用可以产生高度合作的激酶反应的受体配体占有率的变化。E.大肠杆菌阵列的一个重要特征是可能存在六聚体CheW环，其通过CheW分子与不直接结合到CheA-CheW环的受体三聚体的成员的相互作用形成。在这里，我们开发了一种体内半胱氨酸定向交联试验来检测这种咀嚼环，并探讨了它们的形成和参与阵列组装的要求。我们发现，咀嚼环的形成变化很大，与细胞的咀嚼丰富，严格依赖于存在的受体能够三聚体的二聚体的安排，并可能发生在没有CheA。然而，不能形成CheW寡聚体的CheA~CheW融合蛋白的交联研究表明，CheW环对于含有CheA的阵列的组装不是必需的。含有不同量的CheW环与体内荧光共振能量转移（FRET）为基础的激酶测定的阵列的信号转导特性的调查显示，CheW环增强的协同性和灵敏度的引诱剂的响应。我们建议，六元咀嚼环提供所需的化学传感器阵列的最佳信号和梯度跟踪性能的额外的互连性。
The Escherichia coli chemoreceptor array is a supramolecular assembly that displays extraordinary signaling capabilities for which the mechanistic basis is only partly understood. The array has a conserved architecture in which transmembrane receptors, organized as trimers of dimers, are connected at their cytoplasmic tips by hexameric rings of alternating kinase CheA and scaffolding protein CheW molecules (CheA-CheW rings). These intermolecular interactions can produce highly cooperative kinase responses to changes in receptor ligand occupancy. An uncharacterized feature of E. coli arrays is the possible presence of hexameric CheW rings, formed by interactions of CheW molecules with the members of receptor trimers that are not directly bound to CheA-CheW rings. Here, we developed an in vivo cysteine-directed crosslinking assay to detect such CheW rings and explored the requirements for their formation and their participation in array assembly. We found that CheW ring formation varied greatly with cellular CheW abundance, strictly depended on the presence of receptors capable of a trimer-of-dimers arrangement, and could occur in the absence of CheA. Nevertheless, crosslinking studies of a CheA~CheW fusion protein incapable of forming CheW oligomers demonstrated that CheW rings were not essential for assembly of CheA-containing arrays. Investigation of the signaling properties of arrays containing variable amounts of CheW rings with in vivo fluorescence resonance energy transfer (FRET)-based kinase assays revealed that CheW rings enhanced the cooperativity and the sensitivity of the responses to attractants. We propose that six-membered CheW rings provide the additional interconnectivity required for optimal signaling and gradient-tracking performance by chemosensory arrays.
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影响因子：
2.9
作者：
Briegel A;Wong ML;Hodges HL;Oikonomou CM;Piasta KN;Harris MJ;Fowler DJ;Thompson LK;Falke JJ;Kiessling LL;Jensen GJ
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