Azospirillum brasilense AerC and Tlp4b Cytoplasmic Chemoreceptors Are Promiscuous and Interact with the Two Membrane-Bound Chemotaxis Signaling Clusters Mediating Chemotaxis Responses
Azospirillum brasilense AerC and Tlp4b Cytoplasmic Chemoreceptors Are Promiscuous and Interact with the Two Membrane-Bound Chemotaxis Signaling Clusters Mediating Chemotaxis Responses
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DOI：
10.1128/jb.00484-22
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发表时间：
2023-05
影响因子：
3.2
通讯作者：
E. Ganusova;Madison Rost;A. Aksenova;Mustafa Abdulhussein;Alisha Holden;G. Alexandre
中科院分区：
文献类型：
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作者：
E. Ganusova;Madison Rost;A. Aksenova;Mustafa Abdulhussein;Alisha Holden;G. Alexandre
细胞质化学感受器占细菌和古细菌基因组中编码的所有化学感受器的约14%，但关于它们如何与膜结合趋化性信号簇的大极性组装体相互作用和功能知之甚少。在这里，我们表明，两个可溶性的化学感受器的作用，在趋化性是混杂的，并与两个不同的膜结合的趋化性信号簇，控制所有的趋化性反应Azocellum brasilense。细菌和细菌的趋化性依赖于由膜结合的化学感受器组成的六边形极性阵列的存在，这些化学感受器与基板信号蛋白的环相互作用。在alphaproteobacterium Azoacellum brasilense中，趋化性由两个趋化性信号系统（Che 1和Che 4）控制，所述趋化性信号系统在两个空间上不同的膜结合化学感受器阵列的基板处混合。跨膜化学受体在趋化性信号簇中的亚细胞定位和组织已得到很好的表征，但可溶性化学受体的亚细胞定位和组织仍相对不足。通过结合诱变，显微镜和生化分析，我们表明，细胞质化学受体AerC和Tlp4b的功能在趋化性和本地化，并与膜结合的化学受体和趋化性信号蛋白从两个极性阵列相互作用，表明可溶性化学受体是混杂的。AerC和Tlp4b与极性趋化性信号簇的相互作用是不等价的，并提示不同的功能。Tlp4b，而不是AerC，通过未知的机制调节信号簇内化学受体的丰度。AerC化学受体，而不是Tlp4b，能够根据其表达水平进出趋化性信号簇。我们还确定了作用的趋化性信号簇的化学感受器组合物在调节其极性亚细胞组织。组织的趋化性信号蛋白作为大型膜结合阵列的趋化敏感性的基础。我们的研究结果表明，化学感受器的组合物可以微调趋化性信号不仅通过其化学感受特异性，但也通过其在极性趋化性信号簇的组织中的作用。细胞质化学感受器占细菌和古细菌基因组中编码的所有化学感受器的约14%，但关于它们如何与膜结合趋化性信号簇的大极性组装体相互作用和功能知之甚少。在这里，我们表明，两个可溶性的化学感受器的作用，在趋化性是混杂的，并与两个不同的膜结合的趋化性信号簇，控制所有的趋化性反应Azocellum brasilense。我们还发现，任何变化的趋化性信号簇的化学感受器组合物改变其极性组织，这表明趋化性信号簇的感觉特异性和它们的极性膜组织之间的动态相互作用。
Cytoplasmic chemoreceptors represent about 14% of all chemoreceptors encoded in bacterial and archaeal genomes, but little is known about how they interact with and function in large polar assemblies of membrane-bound chemotaxis signaling clusters. Here, we show that two soluble chemoreceptors with a role in chemotaxis are promiscuous and interact with two distinct membrane-bound chemotaxis signaling clusters that control all chemotaxis responses in Azospirillum brasilense. ABSTRACT Chemotaxis in Bacteria and Archaea depends on the presence of hexagonal polar arrays composed of membrane-bound chemoreceptors that interact with rings of baseplate signaling proteins. In the alphaproteobacterium Azospirillum brasilense, chemotaxis is controlled by two chemotaxis signaling systems (Che1 and Che4) that mix at the baseplates of two spatially distinct membrane-bound chemoreceptor arrays. The subcellular localization and organization of transmembrane chemoreceptors in chemotaxis signaling clusters have been well characterized but those of soluble chemoreceptors remain relatively underexplored. By combining mutagenesis, microscopy, and biochemical assays, we show that the cytoplasmic chemoreceptors AerC and Tlp4b function in chemotaxis and localize to and interact with membrane-bound chemoreceptors and chemotaxis signaling proteins from both polar arrays, indicating that soluble chemoreceptors are promiscuous. The interactions of AerC and Tlp4b with polar chemotaxis signaling clusters are not equivalent and suggest distinct functions. Tlp4b, but not AerC, modulates the abundance of chemoreceptors within the signaling clusters through an unknown mechanism. The AerC chemoreceptor, but not Tlp4b, is able to traffic in and out of chemotaxis signaling clusters depending on its level of expression. We also identify a role of the chemoreceptor composition of chemotaxis signaling clusters in regulating their polar subcellular organization. The organization of chemotaxis signaling proteins as large membrane-bound arrays underlies chemotaxis sensitivity. Our findings suggest that the composition of chemoreceptors may fine-tune chemotaxis signaling not only through their chemosensory specificity but also through their role in the organization of polar chemotaxis signaling clusters. IMPORTANCE Cytoplasmic chemoreceptors represent about 14% of all chemoreceptors encoded in bacterial and archaeal genomes, but little is known about how they interact with and function in large polar assemblies of membrane-bound chemotaxis signaling clusters. Here, we show that two soluble chemoreceptors with a role in chemotaxis are promiscuous and interact with two distinct membrane-bound chemotaxis signaling clusters that control all chemotaxis responses in Azospirillum brasilense. We also found that any change in the chemoreceptor composition of chemotaxis signaling clusters alters their polar organization, suggesting a dynamic interplay between the sensory specificity of chemotaxis signaling clusters and their polar membrane organization.