Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS
7-Hydroxytropolone (7-HT) is a unique iron scavenger synthesized by <i>Pseudomonas donghuensis</i> HYS that has various biological activities in addition to functioning as a siderophore. <i>P. donghuensis</i> HYS is more pathogenic than <i>P. aeruginosa</i> toward...
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MDPI AG
2023-01-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/2/1184 |
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| author | Shiyu Teng Tingting Wu Donghao Gao Siyi Wu Yaqian Xiao Yan Long Zhixiong Xie |
| author_facet | Shiyu Teng Tingting Wu Donghao Gao Siyi Wu Yaqian Xiao Yan Long Zhixiong Xie |
| author_sort | Shiyu Teng |
| collection | DOAJ |
| description | 7-Hydroxytropolone (7-HT) is a unique iron scavenger synthesized by <i>Pseudomonas donghuensis</i> HYS that has various biological activities in addition to functioning as a siderophore. <i>P. donghuensis</i> HYS is more pathogenic than <i>P. aeruginosa</i> toward <i>Caenorhabditis elegans</i>, an observation that is closely linked to the biosynthesis of 7-HT. The nonfluorescent siderophore (<i>nfs</i>) gene cluster is responsible for the orderly biosynthesis of 7-HT and represents a competitive advantage that contributes to the increased survival of <i>P. donghuensis</i> HYS; however, the regulatory mechanisms of 7-HT biosynthesis remain unclear. This study is the first to propose that the ECF σ factor has a regulatory effect on 7-HT biosynthesis. In total, 20 ECF σ factors were identified through genome-wide scanning, and their responses to extracellular ferrous ions were characterized. We found that SigW was both significantly upregulated under high-iron conditions and repressed by an adjacent anti-σ factor. RNA-Seq results suggest that the SigW/RsiW system is involved in iron metabolism and 7-HT biosynthesis. Combined with the siderophore phenotype, we also found that SigW could inhibit siderophore synthesis, and this inhibition can be relieved by RsiW. EMSA assays proved that SigW, when highly expressed, can directly bind to the promoter region of five operons of the <i>nfs</i> cluster to inhibit the transcription of the corresponding genes and consequently suppress 7-HT biosynthesis. In addition, SigW not only directly negatively regulates structural genes related to 7-HT synthesis but also inhibits the transcription of regulatory proteins, including of the Gac/Rsm cascade system. Taken together, our results highlight that the biosynthesis of 7-HT is negatively regulated by SigW and that the SigW/RsiW system is involved in mechanisms for the regulation of iron homeostasis in <i>P. donghuensis</i> HYS. As a result of this work, we identified a novel mechanism for the global negative regulation of 7-HT biosynthesis, complementing our understanding of the function of ECF σ factors in <i>Pseudomonas</i>. |
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| issn | 1661-6596 1422-0067 |
| language | English |
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| spelling | doaj.art-ddf4f1d52c3d4317a6cfea9ea9379c562023-11-30T22:36:38ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-01-01242118410.3390/ijms24021184Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYSShiyu Teng0Tingting Wu1Donghao Gao2Siyi Wu3Yaqian Xiao4Yan Long5Zhixiong Xie6Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China7-Hydroxytropolone (7-HT) is a unique iron scavenger synthesized by <i>Pseudomonas donghuensis</i> HYS that has various biological activities in addition to functioning as a siderophore. <i>P. donghuensis</i> HYS is more pathogenic than <i>P. aeruginosa</i> toward <i>Caenorhabditis elegans</i>, an observation that is closely linked to the biosynthesis of 7-HT. The nonfluorescent siderophore (<i>nfs</i>) gene cluster is responsible for the orderly biosynthesis of 7-HT and represents a competitive advantage that contributes to the increased survival of <i>P. donghuensis</i> HYS; however, the regulatory mechanisms of 7-HT biosynthesis remain unclear. This study is the first to propose that the ECF σ factor has a regulatory effect on 7-HT biosynthesis. In total, 20 ECF σ factors were identified through genome-wide scanning, and their responses to extracellular ferrous ions were characterized. We found that SigW was both significantly upregulated under high-iron conditions and repressed by an adjacent anti-σ factor. RNA-Seq results suggest that the SigW/RsiW system is involved in iron metabolism and 7-HT biosynthesis. Combined with the siderophore phenotype, we also found that SigW could inhibit siderophore synthesis, and this inhibition can be relieved by RsiW. EMSA assays proved that SigW, when highly expressed, can directly bind to the promoter region of five operons of the <i>nfs</i> cluster to inhibit the transcription of the corresponding genes and consequently suppress 7-HT biosynthesis. In addition, SigW not only directly negatively regulates structural genes related to 7-HT synthesis but also inhibits the transcription of regulatory proteins, including of the Gac/Rsm cascade system. Taken together, our results highlight that the biosynthesis of 7-HT is negatively regulated by SigW and that the SigW/RsiW system is involved in mechanisms for the regulation of iron homeostasis in <i>P. donghuensis</i> HYS. As a result of this work, we identified a novel mechanism for the global negative regulation of 7-HT biosynthesis, complementing our understanding of the function of ECF σ factors in <i>Pseudomonas</i>.https://www.mdpi.com/1422-0067/24/2/1184<i>Pseudomonas donghuensis</i> HYSSigWanti-σ factornegative regulatorsiderophore7-hydroxytropolone |
| spellingShingle | Shiyu Teng Tingting Wu Donghao Gao Siyi Wu Yaqian Xiao Yan Long Zhixiong Xie Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS International Journal of Molecular Sciences <i>Pseudomonas donghuensis</i> HYS SigW anti-σ factor negative regulator siderophore 7-hydroxytropolone |
| title | Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS |
| title_full | Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS |
| title_fullStr | Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS |
| title_full_unstemmed | Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS |
| title_short | Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in <i>Pseudomonas donghuensis</i> HYS |
| title_sort | insight into the global negative regulation of iron scavenger 7 ht biosynthesis by the sigw rsiw system in i pseudomonas donghuensis i hys |
| topic | <i>Pseudomonas donghuensis</i> HYS SigW anti-σ factor negative regulator siderophore 7-hydroxytropolone |
| url | https://www.mdpi.com/1422-0067/24/2/1184 |
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