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Gu Y, Yang Y, Kou C, Peng Y, Yang W, Zhang J, Jin H, Han X, Wang Y, Shen X. Classical and novel properties of Holliday junction resolvase SynRuvC from Synechocystis sp. PCC6803. Front Microbiol 2024; 15:1362880. [PMID: 38699476 PMCID: PMC11063404 DOI: 10.3389/fmicb.2024.1362880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 03/29/2024] [Indexed: 05/05/2024] Open
Abstract
Cyanobacteria, which have a photoautotrophic lifestyle, are threatened by ultraviolet solar rays and the reactive oxygen species generated during photosynthesis. They can adapt to environmental conditions primarily because of their DNA damage response and repair mechanisms, notably an efficient homologous recombination repair system. However, research on double-strand break (DSB) repair pathways, including the Holliday junction (HJ) resolution process, in Synechocystis sp. PCC6803 is limited. Here, we report that SynRuvC from cyanobacteria Synechocystis sp. PCC6803 has classical HJ resolution activity. We investigated the structural specificity, sequence preference, and biochemical properties of SynRuvC. SynRuvC strongly preferred Mn2+ as a cofactor, and its cleavage site predominantly resides within the 5'-TG↓(G/A)-3' sequence. Interestingly, novel flap endonuclease and replication fork intermediate cleavage activities of SynRuvC were also determined, which distinguish it from other reported RuvCs. To explore the effect of SynRuvC on cell viability, we constructed a knockdown mutant and an overexpression strain of Synechocystis sp. PCC6803 (synruvCKD and synruvCOE) and assessed their survival under a variety of conditions. Knockdown of synruvC increased the sensitivity of cells to MMS, HU, and H2O2. The findings suggest that a novel RuvC family HJ resolvase SynRuvC is important in a variety of DNA repair processes and stress resistance in Synechocystis sp. PCC6803.
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Affiliation(s)
- Yanchao Gu
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Yantao Yang
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Chunhua Kou
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Ying Peng
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Wenguang Yang
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Jiayu Zhang
- Suzhou XinBio Co., Ltd., Suzhou, Jiangsu, China
| | - Han Jin
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaoru Han
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Yao Wang
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Xihui Shen
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
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Brochu J, Vlachos-Breton É, Irsenco D, Drolet M. Characterization of a pathway of genomic instability induced by R-loops and its regulation by topoisomerases in E. coli. PLoS Genet 2023; 19:e1010754. [PMID: 37141391 DOI: 10.1371/journal.pgen.1010754] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/16/2023] [Accepted: 04/21/2023] [Indexed: 05/06/2023] Open
Abstract
The prototype enzymes of the ubiquitous type IA topoisomerases (topos) family are Escherichia coli topo I (topA) and topo III (topB). Topo I shows preference for relaxation of negative supercoiling and topo III for decatenation. However, as they could act as backups for each other or even share functions, strains lacking both enzymes must be used to reveal the roles of type IA enzymes in genome maintenance. Recently, marker frequency analysis (MFA) of genomic DNA from topA topB null mutants revealed a major RNase HI-sensitive DNA peak bordered by Ter/Tus barriers, sites of replication fork fusion and termination in the chromosome terminus region (Ter). Here, flow cytometry for R-loop-dependent replication (RLDR), MFA, R-loop detection with S9.6 antibodies, and microscopy were used to further characterize the mechanism and consequences of over-replication in Ter. It is shown that the Ter peak is not due to the presence of a strong origin for RLDR in Ter region; instead RLDR, which is partly inhibited by the backtracking-resistant rpoB*35 mutation, appears to contribute indirectly to Ter over-replication. The data suggest that RLDR from multiple sites on the chromosome increases the number of replication forks trapped at Ter/Tus barriers which leads to RecA-dependent DNA amplification in Ter and to a chromosome segregation defect. Overproducing topo IV, the main cellular decatenase, does not inhibit RLDR or Ter over-replication but corrects the chromosome segregation defect. Furthermore, our data suggest that the inhibition of RLDR by topo I does not require its C-terminal-mediated interaction with RNA polymerase. Overall, our data reveal a pathway of genomic instability triggered by R-loops and its regulation by various topos activities at different steps.
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Affiliation(s)
- Julien Brochu
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Canada
| | - Émilie Vlachos-Breton
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Canada
| | - Dina Irsenco
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Canada
| | - Marc Drolet
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Canada
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Kuzmenko A, Oguienko A, Esyunina D, Yudin D, Petrova M, Kudinova A, Maslova O, Ninova M, Ryazansky S, Leach D, Aravin AA, Kulbachinskiy A. DNA targeting and interference by a bacterial Argonaute nuclease. Nature 2020; 587:632-637. [PMID: 32731256 DOI: 10.1038/s41586-020-2605-1] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/24/2020] [Indexed: 12/21/2022]
Abstract
Members of the conserved Argonaute protein family use small RNA guides to locate their mRNA targets and regulate gene expression and suppress mobile genetic elements in eukaryotes1,2. Argonautes are also present in many bacterial and archaeal species3-5. Unlike eukaryotic proteins, several prokaryotic Argonaute proteins use small DNA guides to cleave DNA, a process known as DNA interference6-10. However, the natural functions and targets of DNA interference are poorly understood, and the mechanisms of DNA guide generation and target discrimination remain unknown. Here we analyse the activity of a bacterial Argonaute nuclease from Clostridium butyricum (CbAgo) in vivo. We show that CbAgo targets multicopy genetic elements and suppresses the propagation of plasmids and infection by phages. CbAgo induces DNA interference between homologous sequences and triggers DNA degradation at double-strand breaks in the target DNA. The loading of CbAgo with locus-specific small DNA guides depends on both its intrinsic endonuclease activity and the cellular double-strand break repair machinery. A similar interaction was reported for the acquisition of new spacers during CRISPR adaptation, and prokaryotic genomes that encode Ago nucleases are enriched in CRISPR-Cas systems. These results identify molecular mechanisms that generate guides for DNA interference and suggest that the recognition of foreign nucleic acids by prokaryotic defence systems involves common principles.
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Affiliation(s)
- Anton Kuzmenko
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia. .,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Anastasiya Oguienko
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Daria Esyunina
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Denis Yudin
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia.,Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Mayya Petrova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Alina Kudinova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Olga Maslova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Maria Ninova
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sergei Ryazansky
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - David Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Alexei A Aravin
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia. .,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
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Sinha AK, Possoz C, Leach DRF. The Roles of Bacterial DNA Double-Strand Break Repair Proteins in Chromosomal DNA Replication. FEMS Microbiol Rev 2020; 44:351-368. [PMID: 32286623 PMCID: PMC7326373 DOI: 10.1093/femsre/fuaa009] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/09/2020] [Indexed: 02/06/2023] Open
Abstract
It is well established that DNA double-strand break (DSB) repair is required to underpin chromosomal DNA replication. Because DNA replication forks are prone to breakage, faithful DSB repair and correct replication fork restart are critically important. Cells, where the proteins required for DSB repair are absent or altered, display characteristic disturbances to genome replication. In this review, we analyze how bacterial DNA replication is perturbed in DSB repair mutant strains and explore the consequences of these perturbations for bacterial chromosome segregation and cell viability. Importantly, we look at how DNA replication and DSB repair processes are implicated in the striking recent observations of DNA amplification and DNA loss in the chromosome terminus of various mutant Escherichia coli strains. We also address the mutant conditions required for the remarkable ability to copy the entire E. coli genome, and to maintain cell viability, even in the absence of replication initiation from oriC, the unique origin of DNA replication in wild type cells. Furthermore, we discuss the models that have been proposed to explain these phenomena and assess how these models fit with the observed data, provide new insights and enhance our understanding of chromosomal replication and termination in bacteria.
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Affiliation(s)
- Anurag Kumar Sinha
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen, 2200, Denmark
| | - Christophe Possoz
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 1 avenue de la Terrasse Building 26, 91198 Gif-sur-Yvette, France
| | - David R F Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, King's Buildings, Edinburgh, EH9 3FF, United Kingdom
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