Cotranscriptional R-loop formation by Mfd involves topological partitioning of DNA
| Autor: | Terence R. Strick, James R. Portman, Jack M Bollins, Nigel J. Savery, Gwendolyn M Brouwer |
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| Rok vydání: | 2021 |
| Předmět: |
Transcription
Genetic R-loop Supercoiling Mfd single molecule magnetic trapping 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Bacterial Proteins Transcription (biology) RNA polymerase Escherichia coli Gene 030304 developmental biology 0303 health sciences Multidisciplinary Chemistry RNA Single-molecule DNA-Directed RNA Polymerases R-loops Biological Sciences Single Molecule Imaging Cell biology Biophysics and Computational Biology Topological domain Mutation Nucleic acid transcription-coupled repair DNA supercoil R-Loop Structures Transcription 030217 neurology & neurosurgery DNA mutagenesis Transcription Factors |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America Portman, J R, Brouwer, G M, Bollins, J M, Savery, N J & Strick, T R 2021, ' Cotranscriptional R-loop formation by Mfd involves topological partitioning of DNA ', Proceedings of the National Academy of Sciences of the United States of America, vol. 118, no. 15, e2019630118 . https://doi.org/10.1073/pnas.2019630118 |
| ISSN: | 1091-6490 |
| Popis: | Significance R-loop structures pose a threat to genomic integrity because their formation can lead to mutagenesis. Mutagenesis drives antibiotic resistance in bacteria and chemotherapy resistance in human cancers; therefore, it is important to understand how R-loops form. Using a combination of in vitro single-molecule experimentation and in vivo mutagenesis assays, we have shown how Mfd, a bacterial protein known for its role in DNA repair, can interact with RNA polymerase to form R-loops. This interaction generates a topological domain in DNA that is highly prone to R-loop formation. The observed mechanism relies on properties of Mfd that are shared by many other proteins, hinting that this is a potentially universal model for R-loop formation. R-loops are nucleic acid hybrids which form when an RNA invades duplex DNA to pair with its template sequence. Although they are implicated in a growing number of gene regulatory processes, their mechanistic origins remain unclear. We here report real-time observations of cotranscriptional R-loop formation at single-molecule resolution and propose a mechanism for their formation. We show that the bacterial Mfd protein can simultaneously interact with both elongating RNA polymerase and upstream DNA, tethering the two together and partitioning the DNA into distinct supercoiled domains. A highly negatively supercoiled domain forms in between Mfd and RNA polymerase, and compensatory positive supercoiling appears in front of the RNA polymerase and behind Mfd. The nascent RNA invades the negatively supercoiled domain and forms a stable R-loop that can drive mutagenesis. This mechanism theoretically enables any protein that simultaneously binds an actively translocating RNA polymerase and upstream DNA to stimulate R-loop formation. |
| Databáze: | OpenAIRE |
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