Localized modulation of DNA supercoiling, triggered by the Shigella anti-silencer VirB, is sufficient to relieve H-NS-mediated silencing
| العنوان: | Localized modulation of DNA supercoiling, triggered by the Shigella anti-silencer VirB, is sufficient to relieve H-NS-mediated silencing |
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| المؤلفون: | Michael A Picker, Monika M A Karney, Taylor M Gerson, Alexander D Karabachev, Juan C Duhart, Joy A McKenna, Helen J Wing |
| المصدر: | Nucleic Acids Research. 51:3679-3695 |
| بيانات النشر: | Oxford University Press (OUP), 2023. |
| سنة النشر: | 2023 |
| مصطلحات موضوعية: | Genetics |
| الوصف: | In Bacteria, nucleoid structuring proteins govern nucleoid dynamics and regulate transcription. In Shigella spp., at ≤30°C, the histone-like nucleoid structuring protein (H-NS) transcriptionally silences many genes on the large virulence plasmid. Upon a switch to 37°C, VirB, a DNA binding protein and key transcriptional regulator of Shigella virulence, is produced. VirB functions to counter H-NS-mediated silencing in a process called transcriptional anti-silencing. Here, we show that VirB mediates a loss of negative DNA supercoils from our plasmid-borne, VirB-regulated PicsP-lacZ reporter in vivo. The changes are not caused by a VirB-dependent increase in transcription, nor do they require the presence of H-NS. Instead, the VirB-dependent change in DNA supercoiling requires the interaction of VirB with its DNA binding site, a critical first step in VirB-dependent gene regulation. Using two complementary approaches, we show that VirB:DNA interactions in vitro introduce positive supercoils in plasmid DNA. Subsequently, by exploiting transcription-coupled DNA supercoiling, we reveal that a localized loss of negative supercoils is sufficient to alleviate H-NS-mediated transcriptional silencing independently of VirB. Together, our findings provide novel insight into VirB, a central regulator of Shigella virulence and, more broadly, a molecular mechanism that offsets H-NS-dependent silencing of transcription in bacteria. |
| تدمد: | 1362-4962 0305-1048 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_________::3c11b6c3699f69989ca4c80479dae7b7 https://doi.org/10.1093/nar/gkad088 |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi...........3c11b6c3699f69989ca4c80479dae7b7 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 13624962 03051048 |
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