The motility and chemosensory systems of Rhizobium leguminosarum, their role in symbiosis, and link to PTSNtr regulation,Environmental Microbiology

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The motility and chemosensory systems of Rhizobium leguminosarum, their role in symbiosis, and link to PTSNtr regulation
Environmental Microbiology ( IF 4.3 ) Pub Date : 2024-01-12 , DOI: 10.1111/1462-2920.16570
Samuel T N Aroney ₁ , Francesco Pini ₁ , Celia Kessler ₁ , Philip S Poole ₁ , Carmen Sánchez-Cañizares ₁

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Motility and chemotaxis are crucial processes for soil bacteria and plant–microbe interactions. This applies to the symbiotic bacterium Rhizobium leguminosarum, where motility is driven by flagella rotation controlled by two chemotaxis systems, Che1 and Che2. The Che1 cluster is particularly important in free-living motility prior to the establishment of the symbiosis, with a che1 mutant delayed in nodulation and reduced in nodulation competitiveness. The Che2 system alters bacteroid development and nodule maturation. In this work, we also identified 27 putative chemoreceptors encoded in the R. leguminosarum bv. viciae 3841 genome and characterized its motility in different growth conditions. We describe a metabolism-based taxis system in rhizobia that acts at high concentrations of dicarboxylates to halt motility independent of chemotaxis. Finally, we show how PTS^Ntr influences cell motility, with PTS^Ntr mutants exhibiting reduced swimming in different media. Motility is restored by the active forms of the PTS^Ntr output regulatory proteins, unphosphorylated ManX and phosphorylated PtsN. Overall, this work shows how rhizobia typify soil bacteria by having a high number of chemoreceptors and highlights the importance of the motility and chemotaxis mechanisms in a free-living cell in the rhizosphere, and at different stages of the symbiosis.

中文翻译：

豆根瘤菌的运动和化学感应系统、它们在共生中的作用以及与 PTSNtr 调节的联系

运动性和趋化性是土壤细菌和植物-微生物相互作用的关键过程。这适用于共生细菌豆根瘤菌，其运动由鞭毛旋转驱动，而鞭毛旋转由两个趋化系统 Che1 和 Che2 控制。 Che1簇在共生建立之前的自由生活运动中特别重要， che1突变体延迟结瘤并降低结瘤竞争力。 Che2 系统改变类菌的发育和根瘤的成熟。在这项工作中，我们还鉴定了R.leguminosarum bv 中编码的 27 种假定的化学感受器。 Viciae 3841 基因组并表征了其在不同生长条件下的运动性。我们描述了根瘤菌中基于代谢的趋向系统，该系统在高浓度的二羧酸盐下起作用，以停止独立于趋化性的运动。最后，我们展示了 PTS ^Ntr如何影响细胞运动，PTS ^Ntr突变体在不同介质中表现出游动减少。 PTS ^Ntr输出调节蛋白、未磷酸化的 ManX 和磷酸化的 PtsN 的活性形式可恢复运动性。总体而言，这项工作展示了根瘤菌如何通过拥有大量化学感受器来代表土壤细菌，并强调了根际自由生活细胞以及共生不同阶段的运动和趋化机制的重要性。

更新日期：2024-01-12

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