Shanghai Yangtze River Delta Eco-Environmental Change and Management Observation and Research Station, Ministry of Science and Technology, Ministry of Education, Shanghai, China.
Shanghai Urban Forest Ecosystem Research Station, National Forestry and Grassland Administration, Shanghai Cooperative Innovation Center for Modern Seed Industry, School of Agriculture and Biology, Shanghai Jiao Tong Universitygrid.16821.3c, Shanghai, China.
Microbiol Spectr. 2021 Oct 31;9(2):e0157121. doi: 10.1128/Spectrum.01571-21. Epub 2021 Oct 27.
Iron is an essential element for the growth and survival of pathogenic bacteria; however, it is not fully understood how bacteria sense and respond to iron deficiency or excess. In this study, we show that in Xanthomonas oryzae pv. senses extracytoplasmic iron and changes the hydrogen bonding network of ligand channel domains by adenosine-to-inosine (A-to-I) RNA editing. The frequency of A-to-I RNA editing during iron-deficient conditions increased by 76.87%, which facilitated the passage of iron through the XfeA outer membrane channel. When bacteria were subjected to high iron concentrations, the percentage of A-to-I editing in decreased, which reduced iron transport via XfeA. Furthermore, A-to-I RNA editing increased expression of multiple genes in the chemotaxis pathway, including methyl-accepting chemotaxis proteins (MCPs) that sense concentrations of exogenous ferrienterobactin (Fe-Ent) at the cytoplasmic membrane. A-to-I RNA editing helps X. oryzae pv. move toward an iron-rich environment and supports our contention that editing in facilitates entry of a ferric siderophore. Overall, our results reveal a new signaling mechanism that bacteria use to adjust to iron concentrations. Adenosine-to-inosine (A-to-I) RNA editing, which is catalyzed by the adenosine deaminase RNA-specific family of enzymes, is a frequent posttranscriptional modification in metazoans. Research on A-to-I editing in bacteria is limited, and the importance of this editing is underestimated. In this study, we show that bacteria may use A-to-I editing as an alternative strategy to promote uptake of metabolic iron, and this form of editing can quickly and precisely modify RNA and subsequent protein sequences similar to an "on/off" switch. Thus, bacteria have the capacity to use a rapid switch-like mechanism to facilitate iron uptake and improve their competitiveness.
铁是致病细菌生长和存活所必需的元素；然而，细菌如何感知和响应缺铁或铁过量的情况还不完全清楚。在这项研究中，我们表明， 在 感受细胞外铁，并通过腺苷到肌苷（A-to-I）RNA 编辑改变配体通道结构域的氢键网络。缺铁条件下 A-to-I RNA 编辑的频率增加了 76.87%，这促进了铁通过 XfeA 外膜通道的传递。当细菌受到高浓度铁时， 中 A-to-I 编辑的百分比降低，这减少了通过 XfeA 的铁运输。此外，A-to-I RNA 编辑增加了趋化途径中多个基因的表达，包括感受细胞质膜中外源铁载体（Fe-Ent）浓度的甲基接受趋化蛋白（MCP）。A-to-I RNA 编辑有助于 向富含铁的环境移动，并支持我们的观点，即 中的编辑有助于进入三价铁载体。总的来说，我们的研究结果揭示了一种新的细菌信号机制，用于调节铁浓度。由腺苷脱氨酶 RNA 特异性酶家族催化的腺苷到肌苷（A-to-I）RNA 编辑是后生动物中一种常见的转录后修饰。关于细菌中 A-to-I 编辑的研究有限，并且这种编辑的重要性被低估了。在这项研究中，我们表明细菌可能将 A-to-I 编辑作为促进代谢铁摄取的替代策略，并且这种编辑形式可以快速而精确地修饰 RNA 及其后续蛋白质序列，类似于“开/关”开关。因此，细菌具有利用快速开关样机制促进铁摄取和提高竞争力的能力。
