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Mota C, Webster M, Saidi M, Kapp U, Zubieta C, Giachin G, Manso JA, de Sanctis D. Metal ion activation and DNA recognition by the Deinococcus radiodurans manganese sensor DR2539. FEBS J 2024; 291:3384-3402. [PMID: 38652591 DOI: 10.1111/febs.17140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/14/2024] [Accepted: 04/10/2024] [Indexed: 04/25/2024]
Abstract
The accumulation of manganese ions is crucial for scavenging reactive oxygen species and protecting the proteome of Deinococcus radiodurans (Dr). However, metal homeostasis still needs to be tightly regulated to avoid toxicity. DR2539, a dimeric transcription regulator, plays a key role in Dr manganese homeostasis. Despite comprising three well-conserved domains - a DNA-binding domain, a dimerisation domain, and an ancillary domain - the mechanisms underlying both, metal ion activation and DNA recognition remain elusive. In this study, we present biophysical analyses and the structure of the dimerisation and DNA-binding domains of DR2539 in its holo-form and in complex with the 21 base pair pseudo-palindromic repeat of the dr1709 promoter region, shedding light on these activation and recognition mechanisms. The dimer presents eight manganese binding sites that induce structural conformations essential for DNA binding. The analysis of the protein-DNA interfaces elucidates the significance of Tyr59 and helix α3 sequence in the interaction with the DNA. Finally, the structure in solution as determined by small-angle X-ray scattering experiments and supported by AlphaFold modeling provides a model illustrating the conformational changes induced upon metal binding.
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Affiliation(s)
- Cristiano Mota
- ESRF - The European Synchrotron, Grenoble, France
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO, Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | | | | | - Ulrike Kapp
- ESRF - The European Synchrotron, Grenoble, France
| | | | | | - José Antonio Manso
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
- I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
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2
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Kyriukha Y, Watkins MB, Redington JM, Dastvan R, Uversky VN, Hopkins JB, Pozzi N, Korolev S. The strand exchange domain of tumor suppressor PALB2 is intrinsically disordered and promotes oligomerization-dependent DNA compaction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.01.543259. [PMID: 37333393 PMCID: PMC10274692 DOI: 10.1101/2023.06.01.543259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The Partner and Localizer of BRCA2 (PALB2) is a scaffold protein that links BRCA1 with BRCA2 to initiate homologous recombination (HR). PALB2 interaction with DNA strongly enhances HR efficiency in cells. The PALB2 DNA-binding domain (PALB2-DBD) supports strand exchange, a complex multistep reaction conducted by only a few proteins such as RecA-like recombinases and Rad52. Using bioinformatics analysis, small-angle X-ray scattering, circular dichroism, and electron paramagnetic spectroscopy, we determined that PALB2-DBD is an intrinsically disordered region (IDR) forming compact molten globule-like dimer. IDRs contribute to oligomerization synergistically with the coiled-coil interaction. Using confocal single-molecule FRET we demonstrated that PALB2-DBD compacts single-stranded DNA even in the absence of DNA secondary structures. The compaction is bimodal, oligomerization-dependent, and is driven by IDRs, suggesting a novel strand exchange mechanism. Intrinsically disordered proteins (IDPs) are prevalent in the human proteome. Novel DNA binding properties of PALB2-DBD and the complexity of strand exchange mechanism significantly expands the functional repertoire of IDPs. Multivalent interactions and bioinformatics analysis suggest that PALB2 function is likely to depend on formation of protein-nucleic acids condensates. Similar intrinsically disordered DBDs may use chaperone-like mechanism to aid formation and resolution of DNA and RNA multichain intermediates during DNA replication, repair and recombination.
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Affiliation(s)
- Yevhenii Kyriukha
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO
| | - Maxwell B Watkins
- The Biophysics Collaborative Access Team (BioCat), Departments of Biology and Physics, Illinois Institute of Technology, Chicago, IL
| | - Jennifer M Redington
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO
| | - Reza Dastvan
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCat), Departments of Biology and Physics, Illinois Institute of Technology, Chicago, IL
| | - Nicola Pozzi
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO
| | - Sergey Korolev
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO
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3
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Hu Z, Bai X. Self-repair and resuscitation of viable injured bacteria in chlorinated drinking water: Achromobacter as an example. WATER RESEARCH 2023; 245:120585. [PMID: 37690414 DOI: 10.1016/j.watres.2023.120585] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/24/2023] [Accepted: 09/04/2023] [Indexed: 09/12/2023]
Abstract
Chlorine disinfection for the treatment of drinking water can cause injury to the membrane and DNA of bacterial cells and may induce the surviving injured bacteria into a viable but non-culturable (VBNC) state. It is difficult to monitor viable injured bacteria by heterotrophic plate counting (HPC), and their presence is also easily miscalculated in flow cytometry intact cell counting (FCM-ICC). Viable injured bacteria have a potential risk of resuscitation in drinking water distribution systems (DWDSs) and pose a threat to public health when drinking from faucets. In this study, bacteria with injured membranes were isolated from chlorinated drinking water by FCM cell sorting. The culture rate of injured bacteria varied from 0.08% to 2.6% on agar plates and 0.39% to 6.5% in 96-well plates. As the dominant genus among the five identified genera, as well as an opportunistic pathogen with multiple antibiotic resistance, Achromobacter was selected and further studied. After treatment with chlorine at a concentration of 1.2 mg/L, Achromobacter entered into the intermediate injured state on the FCM plot, and the injury on the bacterial surface was observed by electron microscopy. However, the CTC respiratory activity assay showed that 75.0% of the bacteria were still physiologically active, and they entered into a VBNC state. The injured VBNC Achromobacter in sterile drinking water were resuscitated after approximately 25 h. The cellular repair behavior of injured bacteria was studied by Fourier transform infrared attenuated total reflectance (FTIR-ATR) and comet assays. It was found that DNA injury rather than membrane injury was repaired first. The expression of Ku and ligD increased significantly during the DNA repair period, indicating that non-homologous end-joining (NHEJ) played an important role in repairing DNA double-strand breaks. This study deepened the understanding of the effect of chlorine disinfection on bacterial viability in drinking water and will provide support for the improvement of the chlorine disinfection process for the treatment of drinking water.
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Affiliation(s)
- Zengyi Hu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaohui Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
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Cox MM, Goodman MF, Keck JL, van Oijen A, Lovett ST, Robinson A. Generation and Repair of Postreplication Gaps in Escherichia coli. Microbiol Mol Biol Rev 2023; 87:e0007822. [PMID: 37212693 PMCID: PMC10304936 DOI: 10.1128/mmbr.00078-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023] Open
Abstract
When replication forks encounter template lesions, one result is lesion skipping, where the stalled DNA polymerase transiently stalls, disengages, and then reinitiates downstream to leave the lesion behind in a postreplication gap. Despite considerable attention in the 6 decades since postreplication gaps were discovered, the mechanisms by which postreplication gaps are generated and repaired remain highly enigmatic. This review focuses on postreplication gap generation and repair in the bacterium Escherichia coli. New information to address the frequency and mechanism of gap generation and new mechanisms for their resolution are described. There are a few instances where the formation of postreplication gaps appears to be programmed into particular genomic locations, where they are triggered by novel genomic elements.
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Affiliation(s)
- Michael M. Cox
- Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Myron F. Goodman
- Department of Biological Sciences, University of Southern California, University Park, Los Angeles, California, USA
- Department of Chemistry, University of Southern California, University Park, Los Angeles, California, USA
| | - James L. Keck
- Department of Biological Chemistry, University of Wisconsin—Madison School of Medicine, Madison, Wisconsin, USA
| | - Antoine van Oijen
- Molecular Horizons, University of Wollongong, Wollongong, New South Wales, Australia
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, Australia
| | - Susan T. Lovett
- Department of Biology, Brandeis University, Waltham, Massachusetts, USA
| | - Andrew Robinson
- Molecular Horizons, University of Wollongong, Wollongong, New South Wales, Australia
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, Australia
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5
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Cho C, Lee D, Jeong D, Kim S, Kim MK, Srinivasan S. Characterization of radiation-resistance mechanism in Spirosoma montaniterrae DY10 T in terms of transcriptional regulatory system. Sci Rep 2023; 13:4739. [PMID: 36959250 PMCID: PMC10036542 DOI: 10.1038/s41598-023-31509-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/13/2023] [Indexed: 03/25/2023] Open
Abstract
To respond to the external environmental changes for survival, bacteria regulates expression of a number of genes including transcription factors (TFs). To characterize complex biological phenomena, a biological system-level approach is necessary. Here we utilized six computational biology methods to infer regulatory network and to characterize underlying biologically mechanisms relevant to radiation-resistance. In particular, we inferred gene regulatory network (GRN) and operons of radiation-resistance bacterium Spirosoma montaniterrae DY10[Formula: see text] and identified the major regulators for radiation-resistance. Our results showed that DNA repair and reactive oxygen species (ROS) scavenging mechanisms are key processes and Crp/Fnr family transcriptional regulator works as a master regulatory TF in early response to radiation.
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Affiliation(s)
- Changyun Cho
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dohoon Lee
- Bioinformatics Institute, Seoul National University, Seoul, 08826, Republic of Korea
- BK21 FOUR Intelligence Computing, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dabin Jeong
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sun Kim
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
- Department of Computer Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Myung Kyum Kim
- Department of Bio & Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 01797, Republic of Korea.
| | - Sathiyaraj Srinivasan
- Department of Bio & Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 01797, Republic of Korea.
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6
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Crystal Structure of the Recombination Mediator Protein RecO from Campylobacter jejuni and Its Interaction with DNA and a Zinc Ion. Int J Mol Sci 2022; 23:ijms23179667. [PMID: 36077065 PMCID: PMC9456098 DOI: 10.3390/ijms23179667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/23/2022] Open
Abstract
Homologous recombination is involved in repairing DNA damage, contributing to maintaining the integrity and stability of viral and cellular genomes. In bacteria, the recombination mediator proteins RecO and RecR are required to load the RecA recombinase on ssDNA for homologous recombination. To structurally and functionally characterize RecO, we determined the crystal structure of RecO from Campylobacter jejuni (cjRecO) at a 1.8 Å resolution and biochemically assessed its capacity to interact with DNA and a metal ion. cjRecO folds into a curved rod-like structure that consists of an N-terminal domain (NTD), C-terminal domain (CTD), and Zn2+-binding domain (ZnD). The ZnD at the end of the rod-like structure coordinates three cysteine residues and one histidine residue to accommodate a Zn2+ ion. Based on an extensive comparative analysis of RecO structures and sequences, we propose that the Zn2+-binding consensus sequence of RecO is CxxC…C/HxxC/H/D. The interaction with Zn2+ is indispensable for the protein stability of cjRecO but does not seem to be required for the recombination mediator function. cjRecO also interacts with ssDNA as part of its biological function, potentially using the positively charged patch in the NTD and CTD. However, cjRecO displays a low ssDNA-binding affinity, suggesting that cjRecO requires RecR to efficiently recognize ssDNA for homologous recombination.
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Pcal_2031, a RecA/Rad51 homologue from Pyrobaculum calidifontis, complements the ultraviolet light sensitivity of Escherichia coli. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01187-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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8
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Alekseev A, Pobegalov G, Morozova N, Vedyaykin A, Cherevatenko G, Yakimov A, Baitin D, Khodorkovskii M. A new insight into RecA filament regulation by RecX from the analysis of conformation-specific interactions. eLife 2022; 11:78409. [PMID: 35730924 PMCID: PMC9252578 DOI: 10.7554/elife.78409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
RecA protein mediates homologous recombination repair in bacteria through assembly of long helical filaments on ssDNA in an ATP-dependent manner. RecX, an important negative regulator of RecA, is known to inhibit RecA activity by stimulating the disassembly of RecA nucleoprotein filaments. Here we use a single-molecule approach to address the regulation of (Escherichia coli) RecA-ssDNA filaments by RecX (E. coli) within the framework of distinct conformational states of RecA-ssDNA filament. Our findings revealed that RecX effectively binds the inactive conformation of RecA-ssDNA filaments and slows down the transition to the active state. Results of this work provide new mechanistic insights into the RecX-RecA interactions and highlight the importance of conformational transitions of RecA filaments as an additional level of regulation of its biological activity.
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Affiliation(s)
- Aleksandr Alekseev
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
| | - Georgii Pobegalov
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
| | - Natalia Morozova
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
| | - Alexey Vedyaykin
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
| | - Galina Cherevatenko
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
| | - Alexander Yakimov
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
| | - Dmitry Baitin
- Kurchatov Institute, St. Petersburg, Russian Federation
| | - Mikhail Khodorkovskii
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
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Wozniak KJ, Burby PE, Nandakumar J, Simmons LA. Structure and kinase activity of bacterial cell cycle regulator CcrZ. PLoS Genet 2022; 18:e1010196. [PMID: 35576203 PMCID: PMC9135335 DOI: 10.1371/journal.pgen.1010196] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 05/26/2022] [Accepted: 04/09/2022] [Indexed: 11/24/2022] Open
Abstract
CcrZ is a recently discovered cell cycle regulator that connects DNA replication initiation with cell division in pneumococci and may have a similar function in related bacteria. CcrZ is also annotated as a putative kinase, suggesting that CcrZ homologs could represent a novel family of bacterial kinase-dependent cell cycle regulators. Here, we investigate the CcrZ homolog in Bacillus subtilis and show that cells lacking ccrZ are sensitive to a broad range of DNA damage. We demonstrate that increased expression of ccrZ results in over-initiation of DNA replication. In addition, increased expression of CcrZ activates the DNA damage response. Using sensitivity to DNA damage as a proxy, we show that the negative regulator for replication initiation (yabA) and ccrZ function in the same pathway. We show that CcrZ interacts with replication initiation proteins DnaA and DnaB, further suggesting that CcrZ is important for replication timing. To understand how CcrZ functions, we solved the crystal structure bound to AMP-PNP to 2.6 Å resolution. The CcrZ structure most closely resembles choline kinases, consisting of a bilobal structure with a cleft between the two lobes for binding ATP and substrate. Inspection of the structure reveals a major restructuring of the substrate-binding site of CcrZ relative to the choline-binding pocket of choline kinases, consistent with our inability to detect activity with choline for this protein. Instead, CcrZ shows activity on D-ribose and 2-deoxy-D-ribose, indicating adaptation of the choline kinase fold in CcrZ to phosphorylate a novel substrate. We show that integrity of the kinase active site is required for ATPase activity in vitro and for function in vivo. This work provides structural, biochemical, and functional insight into a newly identified, and conserved group of bacterial kinases that regulate DNA replication initiation.
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Affiliation(s)
- Katherine J. Wozniak
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Peter E. Burby
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
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Single-molecule characterization of compressed RecA nucleoprotein filaments. Biochem Biophys Res Commun 2022; 614:29-33. [PMID: 35567941 DOI: 10.1016/j.bbrc.2022.04.130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 04/27/2022] [Indexed: 11/21/2022]
Abstract
RecA is a central enzyme of homologous recombination in bacteria, which plays a major role in DNA repair, natural transformation and SOS-response activation. RecA forms nucleoprotein filaments on single-stranded DNA with a highly conserved architecture that is also shared by eukaryotic recombinases. One of the key features of these filaments is the ability to switch between stretched and compressed conformations in response to ATP binding and hydrolysis. However, the functional role of such conformational changes is not fully understood. Structural data revealed that in the absence of ATP RecA binds DNA with the stoichiometry of 5 nucleotides per one monomer, while in the presence of ATP the binding stoichiometry is 3:1. Such differences suggest incompatibility of the active and inactive conformations, yet dynamic single-molecule studies demonstrated that ATP and apo conformations can be directly interconvertible. In the present work we use a single-molecule approach to address the features of inactive RecA nucleoprotein filaments formed de novo in the absence of nucleotide cofactors. We show that compressed RecA-DNA filaments can exist with both 5:1 and 3:1 binding stoichiometry which is determined by conditions of the filament assembly. However, only a 3:1 stoichiometry allows direct interconvertibility with the active ATP-bound conformation.
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11
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Jain K, Stanage TH, Wood EA, Cox MM. The Escherichia coli serS gene promoter region overlaps with the rarA gene. PLoS One 2022; 17:e0260282. [PMID: 35427362 PMCID: PMC9012371 DOI: 10.1371/journal.pone.0260282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 04/05/2022] [Indexed: 11/25/2022] Open
Abstract
Deletion of the entire gene encoding the RarA protein of Escherichia coli results in a growth defect and additional deficiencies that were initially ascribed to a lack of RarA function. Further work revealed that most of the effects reflected the presence of sequences in the rarA gene that affect expression of the downstream gene, serS. The serS gene encodes the seryl aminoacyl-tRNA synthetase. Decreases in the expression of serS can trigger the stringent response. The sequences that affect serS expression are located in the last 15 nucleotides of the rarA gene.
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Affiliation(s)
- Kanika Jain
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
| | - Tyler H. Stanage
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Elizabeth A. Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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12
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Milhm ACP, Bonet LFS, Aiub CAF, Siqueira Junior CL. Biochemical characterization and phytotoxic activity of protein extract from Euphorbia tirucalli L. JOURNAL OF ETHNOPHARMACOLOGY 2022; 285:114903. [PMID: 34890731 DOI: 10.1016/j.jep.2021.114903] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Euphorbia tirucalli L., a tropical and subtropical plant, also known by the popular name avelós, has been used in folk medicine against many diseases as rheumatism, asthma, toothache, and cancer. Studies have shown that natural compounds contained in this plant species may be associated with these functions. However, little is known about its potential toxicity. AIM OF THE STUDY Several proteins conduct biological functions, in particular, proteinases, play a crucial role in many mechanisms of living beings, including plants, animals and microorganisms. However, when poorly regulated, they can generate consequences, such as the non-production of certain substances, or even the abnormal multiplication of cells, which leads to tumors. On the other hand, by regulating these enzymes, proteinase inhibitors act by reducing the activity of proteinases, thus preventing their malfunction. The objective of this work was to evaluate the toxicity of the protein extract of E. tirucalli and to purify a protease inhibitor that may be associated with the biological medicinal functions of the plant. MATERIALS AND METHODS The cytotoxic and mutagenic properties of the protein extract produced from the stem of avelós was investigated using the Ames test. The protein extract was also submitted to a protease inhibitor purification process using the gel filtration chromatography technique and the purified protein was biochemically characterized. RESULTS A protease inhibitor, called tirustatin, was isolated 1.84-fold by Biogel P100. The calculated molecular mass of the isolated protein is 25.97 kDa. The inhibitor was stable at pH 3-10, with pronounced activity at pH 6. Thermostability was observed even at elevated temperature (100 °C) with inhibitory activity increased by 1.14-fold compared to inhibitor activity at room temperature. Incubation at basic pH values for up to 60 min caused little reduction (0.25-fold) in the papain inhibitory activity of tirustatin. The stoichiometry of the papain-tirustatin interaction was 1.5: 1 and 28.8 pM of the inhibitor effected 50% inhibition. With an equilibrium dissociation constant of 8.74 x 10-8M for the papain enzyme, it is possible to evaluate the isolated protein as a non-competitive inhibitor. In addition, the protein extract of E. tirucalli even at the maximum concentration used (20 μg/mL), did not show a cytotoxic and mutagenic profile in a bacterial model. CONCLUSION The results presented in this work provide data that reinforce the idea of the potential use of proteins produced in E. tirucalli as pharmacological and biotechnological agents that can be exploited for the development of efficient drugs.
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Affiliation(s)
- Ana Carolina Pereira Milhm
- Laboratory of Biochemistry and Function of Plant Proteins, Department of Botany, Federal University of the State of Rio de Janeiro, Av. Pasteur, 458, Urca, Brazil.
| | - Luiz Felippe Sarmento Bonet
- Laboratory of Biochemistry and Function of Plant Proteins, Department of Botany, Federal University of the State of Rio de Janeiro, Av. Pasteur, 458, Urca, Brazil.
| | - Claudia Alessandra Fortes Aiub
- Laboratory of Genotoxicity, Department of Genetics and Molecular Biology, Federal University of the State of Rio de Janeiro, R. Frei Caneca, 94 - Centro, Brazil.
| | - César Luis Siqueira Junior
- Laboratory of Biochemistry and Function of Plant Proteins, Research Center on Agricultural Systems, Department of Botany, Federal University of the State of Rio de Janeiro, Av. Pasteur, 458, Urca, Brazil.
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13
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LeGault KN, Barth ZK, DePaola P, Seed KD. A phage parasite deploys a nicking nuclease effector to inhibit viral host replication. Nucleic Acids Res 2022; 50:8401-8417. [PMID: 35066583 PMCID: PMC9410903 DOI: 10.1093/nar/gkac002] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/17/2021] [Accepted: 01/12/2022] [Indexed: 12/11/2022] Open
Abstract
PLEs (phage-inducible chromosomal island-like elements) are phage parasites integrated into the chromosome of epidemic Vibrio cholerae. In response to infection by its viral host ICP1, PLE excises, replicates and hijacks ICP1 structural components for transduction. Through an unknown mechanism, PLE prevents ICP1 from transitioning to rolling circle replication (RCR), a prerequisite for efficient packaging of the viral genome. Here, we characterize a PLE-encoded nuclease, NixI, that blocks phage development likely by nicking ICP1’s genome as it transitions to RCR. NixI-dependent cleavage sites appear in ICP1’s genome during infection of PLE(+) V. cholerae. Purified NixI demonstrates in vitro nuclease activity specifically for sites in ICP1’s genome and we identify a motif that is necessary for NixI-mediated cleavage. Importantly, NixI is sufficient to limit ICP1 genome replication and eliminate progeny production, representing the most inhibitory PLE-encoded mechanism revealed to date. We identify distant NixI homologs in an expanded family of putative phage parasites in vibrios that lack nucleotide homology to PLEs but nonetheless share genomic synteny with PLEs. More generally, our results reveal a previously unknown mechanism deployed by phage parasites to limit packaging of their viral hosts’ genome and highlight the prominent role of nuclease effectors as weapons in the arms race between antagonizing genomes.
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Affiliation(s)
- Kristen N LeGault
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA
| | - Zachary K Barth
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA
| | - Peter DePaola
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA
| | - Kimberley D Seed
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA.,Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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14
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Si L, Gu J, Wen M, Wang R, Fleming J, Li J, Xu J, Bi L, Deng J. relA Inactivation Converts Sulfonamides Into Bactericidal Compounds. Front Microbiol 2021; 12:698468. [PMID: 34646242 PMCID: PMC8503649 DOI: 10.3389/fmicb.2021.698468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 08/31/2021] [Indexed: 11/13/2022] Open
Abstract
Folates are required for the de novo biosynthesis of purines, thymine, methionine, glycine, and pantothenic acid, key metabolites that bacterial cells cannot survive without. Sulfonamides, which inhibit bacterial folate biosynthesis and are generally considered as bacteriostats, have been extensively used as broad-spectrum antimicrobials for decades. Here we show that, deleting relA in Escherichia coli and other bacterial species converted sulfamethoxazole from a bacteriostat into a bactericide. Not as previously assumed, the bactericidal effect of SMX was not caused by thymine deficiency. When E. coli ∆relA was treated with SMX, reactive oxygen species and ferrous ion accumulated inside the bacterial cells, which caused extensive DNA double-strand breaks without the involvement of incomplete base excision repair. In addition, sulfamethoxazole showed bactericidal effect against E. coli O157 ∆relA in mice, suggesting the possibility of designing new potentiators for sulfonamides targeting RelA. Thus, our study uncovered the previously unknown bactericidal effects of sulfonamides, which advances our understanding of their mechanisms of action, and will facilitate the designing of new potentiators for them.
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Affiliation(s)
- Lizhen Si
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jing Gu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Mi Wen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ruiqi Wang
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Joy Fleming
- Key Laboratory of RNA Biology and National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jinyue Li
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Jintian Xu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lijun Bi
- Key Laboratory of RNA Biology and National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- School of Stomatology and Medicine, Foshan University, Foshan, China
- Guangdong Province Key Laboratory of TB Systems Biology and Translational Medicine, Foshan, China
| | - Jiaoyu Deng
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- Guangdong Province Key Laboratory of TB Systems Biology and Translational Medicine, Foshan, China
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15
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Kiran K, Patil KN. Expression and Characterization of the Staphylococcus aureus RecA protein: A mapping of canonical functions. Protein Expr Purif 2021; 189:105967. [PMID: 34481085 DOI: 10.1016/j.pep.2021.105967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/27/2021] [Accepted: 08/27/2021] [Indexed: 11/16/2022]
Abstract
Recombinases are responsible for homologous recombination (HR), proper genome maintenance, and accurate deoxyribonucleic acid (DNA) duplication. Moreover, HR plays a determining role in DNA transaction processes such as DNA replication, repair, recombination, and transcription. Staphylococcus aureus, an opportunistic pathogen, usually causes respiratory infections such as sinusitis, skin infections, and food poisoning. To date, the role of the RecA gene product in S. aureus remains obscure. In this study, we attempted to map the functional properties of the RecA protein. S. aureus expresses the recA gene product in vivo upon exposure to the DNA-damaging agents, ultraviolet radiation, and methyl methanesulfonate. The recombinant purified S. aureus RecA protein displayed strong single-stranded DNA affinity compared to feeble binding to double-stranded DNA. Interestingly, the RecA protein is capable of invasion and formed displacement loops and readily performed strand-exchange activities with an oligonucleotide-based substrate. Notably, the S. aureus RecA protein hydrolyzed the DNA-dependent adenosine triphosphate and cleaved LexA, showing the conserved function of coprotease. This study provides the functional characterization of the S. aureus RecA protein and sheds light on the canonical processes of homologous recombination, which are conserved in the gram-positive foodborne pathogen S. aureus.
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Affiliation(s)
- Kajal Kiran
- Department of Protein Chemistry and Technology, Council of Scientific & Industrial Research-Central Food Technological Research Institute (CSIR-CFTRI), Mysuru, 570 020, Karnataka, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, Uttar Pradesh, India
| | - K Neelakanteshwar Patil
- Department of Protein Chemistry and Technology, Council of Scientific & Industrial Research-Central Food Technological Research Institute (CSIR-CFTRI), Mysuru, 570 020, Karnataka, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, Uttar Pradesh, India.
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16
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RecA is required for the assembly of RecN into DNA repair complexes on the nucleoid. J Bacteriol 2021; 203:e0024021. [PMID: 34339298 DOI: 10.1128/jb.00240-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Homologous recombination requires the coordinated effort of several proteins to complete break resection, homologous pairing and resolution of DNA crossover structures. RecN is a conserved bacterial protein important of double strand break repair and a member of the Structural Maintenance of Chromosomes (SMC) protein family. Current models in Bacillus subtilis propose that RecN responds to double stranded breaks prior to RecA and end processing suggesting that RecN is among the very first proteins responsible for break detection. Here, we investigate the contribution of RecA and end processing by AddAB to RecN recruitment into repair foci in vivo. Using this approach, we found that recA is required for RecN-GFP focus formation on the nucleoid during normal growth and in response to DNA damage. In the absence of recA function, RecN foci form in a low percentage of cells, RecN localizes away from the nucleoid, and RecN fails to assemble in response to DNA damage. In contrast, we show that the response of RecA-GFP foci to DNA damage is unchanged in the presence or absence of recN. In further support of RecA activity preceding RecN we show that ablation of the double-strand break end processing enzyme addAB results in a failure of RecN to form foci in response to DNA damage. With these results, we conclude that RecA and end processing function prior to RecN establishing a critical step for the recruitment and participation of RecN during DNA break repair in Bacillus subtilis. IMPORTANCE Homologous recombination is important for the repair of DNA double-strand breaks. RecN is a highly conserved protein that has been shown to be important for sister chromatid cohesion and for survival to break-inducing clastogens. Here, we show that the assembly of RecN into repair foci on the bacterial nucleoid requires the end processing enzyme AddAB and the recombinase RecA. In the absence of either recA or end processing RecN-GFP foci are no longer DNA damage inducible and foci form in a subset of cells as large complexes in regions away from the nucleoid. Our results establish the stepwise order of action, where double-strand break end processing and RecA association precede the participation of RecN during break repair in Bacillus subtilis.
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17
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Maman N, Kumar P, Yadav A, Feingold M. Single Molecule Study of the Polymerization of RecA on dsDNA: The Dynamics of Individual Domains. Front Mol Biosci 2021; 8:609076. [PMID: 33842536 PMCID: PMC8025788 DOI: 10.3389/fmolb.2021.609076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 02/02/2021] [Indexed: 11/13/2022] Open
Abstract
In the Escherichia coli, RecA plays a central role in the recombination and repair of the DNA. For homologous recombination, RecA binds to ssDNA forming a nucleoprotein filament. The RecA-ssDNA filament searches for a homologous sequence on a dsDNA and, subsequently, RecA mediates strand exchange between the ssDNA and the dsDNA. In vitro, RecA binds to both ssDNA and dsDNA. Despite a wide range of studies of the polymerization of RecA on dsDNA, both at the single molecule level and by means of biochemical methods, important aspects of this process are still awaiting a better understanding. Specifically, a detailed, quantitative description of the nucleation and growth dynamics of the RecA-dsDNA filaments is still lacking. Here, we use Optical Tweezers together with a single molecule analysis approach to measure the dynamics of the individual RecA domains on dsDNA and the corresponding growth rates for each of their fronts. We focus on the regime where the nucleation and growth rate constants, kn and kg, are comparable, leading to a coverage of the dsDNA molecule that consists of a small number of RecA domains. For the case of essentially irreversible binding (using ATPγS instead of ATP), we find that domain growth is highly asymmetric with a ratio of about 10:1 between the fast and slow fronts growth rates.
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Affiliation(s)
- Nitzan Maman
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel.,The Ilse Katz Center for Nanotechnology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Pramod Kumar
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Amarjeet Yadav
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel.,Department of Applied Physics, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Mario Feingold
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel.,The Ilse Katz Center for Nanotechnology, Ben Gurion University of the Negev, Beer Sheva, Israel
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18
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Bai S, Wang J, Yang K, Zhou C, Xu Y, Song J, Gu Y, Chen Z, Wang M, Shoen C, Andrade B, Cynamon M, Zhou K, Wang H, Cai Q, Oldfield E, Zimmerman SC, Bai Y, Feng X. A polymeric approach toward resistance-resistant antimicrobial agent with dual-selective mechanisms of action. SCIENCE ADVANCES 2021; 7:eabc9917. [PMID: 33571116 PMCID: PMC7840121 DOI: 10.1126/sciadv.abc9917] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 12/08/2020] [Indexed: 05/19/2023]
Abstract
Antibiotic resistance is now a major threat to human health, and one approach to combating this threat is to develop resistance-resistant antibiotics. Synthetic antimicrobial polymers are generally resistance resistant, having good activity with low resistance rates but usually with low therapeutic indices. Here, we report our solution to this problem by introducing dual-selective mechanisms of action to a short amidine-rich polymer, which can simultaneously disrupt bacterial membranes and bind to bacterial DNA. The oligoamidine shows unobservable resistance generation but high therapeutic indices against many bacterial types, such as ESKAPE strains and clinical isolates resistant to multiple drugs, including colistin. The oligomer exhibited excellent effectiveness in various model systems, killing extracellular or intracellular bacteria in the presence of mammalian cells, removing all bacteria from Caenorhabditis elegans, and rescuing mice with severe infections. This "dual mechanisms of action" approach may be a general strategy for future development of antimicrobial polymers.
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Affiliation(s)
- Silei Bai
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Jianxue Wang
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Kailing Yang
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Cailing Zhou
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Yangfan Xu
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Junfeng Song
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Yuanxin Gu
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Zheng Chen
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Min Wang
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Carolyn Shoen
- Veterans Affairs Medical Center, Syracuse, NY 13210, USA
| | - Brenda Andrade
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | - Kai Zhou
- Shenzhen Institute of Respiratory Diseases, The First Affiliated Hospital of Southern University of Science and Technology (Shenzhen People's Hospital), Shenzhen, Guangdong 518035, China
- The Second Clinical Medical College of Jinan University (Shenzhen People's Hospital), Shenzhen, Guangdong 518020, China
| | - Hui Wang
- Department of Clinical Laboratories, Peking University People's Hospital, Beijing, 100044, China
| | - Qingyun Cai
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Eric Oldfield
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Steven C Zimmerman
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yugang Bai
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China.
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Xinxin Feng
- Institute of Chemical Biology and Nanomedicine, Hunan University, Changsha, Hunan 410082, China.
- State Key Laboratory of Chem/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha, Hunan 410082, China
- School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
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19
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Prahlad J, Yuan Y, Lin J, Chang CW, Iwata-Reuyl D, Liu Y, de Crécy-Lagard V, Wilson MA. The DUF328 family member YaaA is a DNA-binding protein with a novel fold. J Biol Chem 2020; 295:14236-14247. [PMID: 32796037 PMCID: PMC7549036 DOI: 10.1074/jbc.ra120.015055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/11/2020] [Indexed: 01/07/2023] Open
Abstract
DUF328 family proteins are present in many prokaryotes; however, their molecular activities are unknown. The Escherichia coli DUF328 protein YaaA is a member of the OxyR regulon and is protective against oxidative stress. Because uncharacterized proteins involved in prokaryotic oxidative stress response are rare, we sought to learn more about the DUF328 family. Using comparative genomics, we found a robust association between the DUF328 family and genes involved in DNA recombination and the oxidative stress response. In some proteins, DUF328 domains are fused to other domains involved in DNA binding, recombination, and repair. Cofitness analysis indicates that DUF328 family genes associate with recombination-mediated DNA repair pathways, particularly the RecFOR pathway. Purified recombinant YaaA binds to dsDNA, duplex DNA containing bubbles of unpaired nucleotides, and Holliday junction constructs in vitro with dissociation equilibrium constants of 200-300 nm YaaA binds DNA with positive cooperativity, forming multiple shifted species in electrophoretic mobility shift assays. The 1.65-Å resolution X-ray crystal structure of YaaA reveals that the protein possesses a new fold that we name the cantaloupe fold. YaaA has a positively charged cleft and a helix-hairpin-helix DNA-binding motif found in other DNA repair enzymes. Our results demonstrate that YaaA is a new type of DNA-binding protein associated with the oxidative stress response and that this molecular function is likely conserved in other DUF328 family members.
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Affiliation(s)
- Janani Prahlad
- Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska, USA
| | - Yifeng Yuan
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Jiusheng Lin
- Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska, USA
| | - Chou-Wei Chang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, California, USA
| | - Dirk Iwata-Reuyl
- Department of Chemistry, Portland State University, Portland, Oregon, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, California, USA
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA,University of Florida Genetics Institute, Gainesville, Florida, USA,For correspondence: Valérie de Crécy-Lagard, ; Mark A. Wilson,
| | - Mark A. Wilson
- Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska, USA,For correspondence: Valérie de Crécy-Lagard, ; Mark A. Wilson,
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20
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Frutos-Grilo E, Marsal M, Irazoki O, Barbé J, Campoy S. The Interaction of RecA With Both CheA and CheW Is Required for Chemotaxis. Front Microbiol 2020; 11:583. [PMID: 32318049 PMCID: PMC7154110 DOI: 10.3389/fmicb.2020.00583] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/17/2020] [Indexed: 12/20/2022] Open
Abstract
Salmonella enterica is the most frequently reported cause of foodborne illness. As in other microorganisms, chemotaxis affords key physiological benefits, including enhanced access to growth substrates, but also plays an important role in infection and disease. Chemoreceptor signaling core complexes, consisting of CheA, CheW and methyl-accepting chemotaxis proteins (MCPs), modulate the switching of bacterial flagella rotation that drives cell motility. These complexes, through the formation of heterohexameric rings composed of CheA and CheW, form large clusters at the cell poles. RecA plays a key role in polar cluster formation, impairing the assembly when the SOS response is activated. In this study, we determined that RecA protein interacts with both CheW and CheA. The binding of these proteins to RecA is needed for wild-type polar cluster formation. In silico models showed that one RecA molecule, attached to one signaling unit, fits within a CheA-CheW ring without interfering with the complex formation or array assembly. Activation of the SOS response is followed by an increase in RecA, which rises up the number of signaling complexes associated with this protein. This suggests the presence of allosteric inhibition in the CheA-CheW interaction and thus of heterohexameric ring formation, impairing the array assembly. STED imaging demonstrated that all core unit components (CheA, CheW, and MPCs) have the same subcellular location as RecA. Activation of the SOS response promotes the RecA distribution along the cell instead of being at the cell poles. CheA- and CheW- RecA interactions are also crucial for chemotaxis, which is maintained when the SOS response is induced and the signaling units are dispersed. Our results provide new molecular-level insights into the function of RecA in chemoreceptor clustering and chemotaxis determining that the impaired chemoreceptor clustering not only inhibits swarming but also modulates chemotaxis in SOS-induced cells, thereby modifying bacterial motility in the presence of DNA-damaging compounds, such as antibiotics.
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Affiliation(s)
- Elisabet Frutos-Grilo
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Maria Marsal
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Oihane Irazoki
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jordi Barbé
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Susana Campoy
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
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21
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Sheng DH, Wang YX, Qiu M, Zhao JY, Yue XJ, Li YZ. Functional Division Between the RecA1 and RecA2 Proteins in Myxococcus xanthus. Front Microbiol 2020; 11:140. [PMID: 32117159 PMCID: PMC7029660 DOI: 10.3389/fmicb.2020.00140] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Myxococcus xanthus DK1622 has two RecA genes, recA1 (MXAN_1441) and recA2 (MXAN_1388), with unknown functional differentiation. Herein, we showed that both recA genes were induced by ultraviolet (UV) irradiation but that the induction of recA1 was more delayed than that of recA2. Deletion of recA1 did not affect the growth but significantly decreased the UV-radiation survival, homologous recombination (HR) ability, and induction of LexA-dependent SOS genes. In contrast, the deletion of recA2 markedly prolonged the lag phase of bacterial growth and increased the sensitivity to DNA damage caused by hydrogen peroxide but did not change the UV-radiation resistance or SOS gene inducibility. Protein activity analysis demonstrated that RecA1, but not RecA2, catalyzed DNA strand exchange (DSE) and LexA autocleavage in vitro. Transcriptomic analysis indicated that RecA2 has evolved mainly to regulate gene expression for cellular transportation and antioxidation. This is the first report of functional divergence of duplicated bacterial recA genes. The results highlight the evolutionary strategy of M. xanthus cells for DNA HR and genome sophistication.
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Affiliation(s)
- Duo-Hong Sheng
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Yi-Xue Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Miao Qiu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Jin-Yi Zhao
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Xin-Jing Yue
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Yue-Zhong Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
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22
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Chauhan N, Wagh V, Joshi P, Jariyal H. ATM and ATR checkpoint kinase pathways: A concise review. ADVANCES IN HUMAN BIOLOGY 2020. [DOI: 10.4103/aihb.aihb_78_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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23
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Lin YH, Chu CC, Fan HF, Wang PY, Cox MM, Li HW. A 5'-to-3' strand exchange polarity is intrinsic to RecA nucleoprotein filaments in the absence of ATP hydrolysis. Nucleic Acids Res 2019; 47:5126-5140. [PMID: 30916331 PMCID: PMC6547424 DOI: 10.1093/nar/gkz189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 03/08/2019] [Accepted: 03/11/2019] [Indexed: 01/13/2023] Open
Abstract
RecA is essential to recombinational DNA repair in which RecA filaments mediate the homologous DNA pairing and strand exchange. Both RecA filament assembly and the subsequent DNA strand exchange are directional. Here, we demonstrate that the polarity of DNA strand exchange is embedded within RecA filaments even in the absence of ATP hydrolysis, at least over short DNA segments. Using single-molecule tethered particle motion, we show that successful strand exchange in the presence of ATP proceeds with a 5′-to-3′ polarity, as demonstrated previously. RecA filaments prepared with ATPγS also exhibit a 5′-to-3′ progress of strand exchange, suggesting that the polarity is not determined by RecA disassembly and/or ATP hydrolysis. RecAΔC17 mutants, lacking a C-terminal autoregulatory flap, also promote strand exchange in a 5′-to-3′ polarity in ATPγS, a polarity that is largely lost with this RecA variant when ATP is hydrolyzed. We propose that there is an inherent strand exchange polarity mediated by the structure of the RecA filament groove, associated by conformation changes propagated in a polar manner as DNA is progressively exchanged. ATP hydrolysis is coupled to polar strand exchange over longer distances, and its contribution to the polarity requires an intact RecA C-terminus.
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Affiliation(s)
- Yu-Hsuan Lin
- Department of Chemistry, National Taiwan University, 10617, Taiwan
| | - Chia-Chieh Chu
- Department of Chemistry, National Taiwan University, 10617, Taiwan
| | - Hsiu-Fang Fan
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, 11221 Taiwan
| | - Pang-Yen Wang
- Department of Chemistry, National Taiwan University, 10617, Taiwan
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin, Madison, 53706, USA
| | - Hung-Wen Li
- Department of Chemistry, National Taiwan University, 10617, Taiwan
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24
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Garud NR, Pollard KS. Population Genetics in the Human Microbiome. Trends Genet 2019; 36:53-67. [PMID: 31780057 DOI: 10.1016/j.tig.2019.10.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/23/2019] [Accepted: 10/24/2019] [Indexed: 02/07/2023]
Abstract
While the human microbiome's structure and function have been extensively studied, its within-species genetic diversity is less well understood. However, genetic mutations in the microbiome can confer biomedically relevant traits, such as the ability to extract nutrients from food, metabolize drugs, evade antibiotics, and communicate with the host immune system. The population genetic processes by which these traits evolve are complex, in part due to interacting ecological and evolutionary forces in the microbiome. Advances in metagenomic sequencing, coupled with bioinformatics tools and population genetic models, facilitate quantification of microbiome genetic variation and inferences about how this diversity arises, evolves, and correlates with traits of both microbes and hosts. In this review, we explore the population genetic forces (mutation, recombination, drift, and selection) that shape microbiome genetic diversity within and between hosts, as well as efforts towards predictive models that leverage microbiome genetics.
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Affiliation(s)
- Nandita R Garud
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA.
| | - Katherine S Pollard
- Gladstone Institutes, San Francisco, CA, USA; Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA, USA.
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25
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Prasad D, Arora D, Nandicoori VK, Muniyappa K. Elucidating the functional role of Mycobacterium smegmatis recX in stress response. Sci Rep 2019; 9:10912. [PMID: 31358794 PMCID: PMC6662834 DOI: 10.1038/s41598-019-47312-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022] Open
Abstract
The RecX protein has attracted considerable interest because the recX mutants exhibit multiple phenotypes associated with RecA functions. To further our understanding of the functional relationship between recA and recX, the effect of different stress treatments on their expression profiles, cell yield and viability were investigated. A significant correlation was found between the expression of Mycobacterium smegmatis recA and recX genes at different stages of growth, and in response to different stress treatments albeit recX exhibiting lower transcript and protein abundance at the mid-log and stationary phases of the bacterial growth cycle. To ascertain their roles in vivo, a targeted deletion of the recX and recArecX was performed in M. smegmatis. The growth kinetics of these mutant strains and their sensitivity patterns to different stress treatments were assessed relative to the wild-type strain. The deletion of recA affected normal cell growth and survival, while recX deletion showed no significant effect. Interestingly, deletion of both recX and recA genes results in a phenotype that is intermediate between the phenotypes of the ΔrecA mutant and the wild-type strain. Collectively, these results reveal a previously unrecognized role for M. smegmatis recX and support the notion that it may regulate a subset of the yet unknown genes involved in normal cell growth and DNA-damage repair.
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Affiliation(s)
- Deepika Prasad
- Department of Biochemistry, Indian Institute of Science, Bengaluru, 560012, India
| | - Divya Arora
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | | | - K Muniyappa
- Department of Biochemistry, Indian Institute of Science, Bengaluru, 560012, India.
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Predominance of Anaerobic, Spore-Forming Bacteria in Metabolically Active Microbial Communities from Ancient Siberian Permafrost. Appl Environ Microbiol 2019; 85:AEM.00560-19. [PMID: 31152014 DOI: 10.1128/aem.00560-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 05/22/2019] [Indexed: 11/20/2022] Open
Abstract
The prevalence of microbial life in permafrost up to several million years (Ma) old has been well documented. However, the long-term survivability, evolution, and metabolic activity of the entombed microbes over this time span remain underexplored. We integrated aspartic acid (Asp) racemization assays with metagenomic sequencing to characterize the microbial activity, phylogenetic diversity, and metabolic functions of indigenous microbial communities across a ∼0.01- to 1.1-Ma chronosequence of continuously frozen permafrost from northeastern Siberia. Although Asp in the older bulk sediments (0.8 to 1.1 Ma) underwent severe racemization relative to that in the youngest sediment (∼0.01 Ma), the much lower d-Asp/l-Asp ratio (0.05 to 0.14) in the separated cells from all samples suggested that indigenous microbial communities were viable and metabolically active in ancient permafrost up to 1.1 Ma. The microbial community in the youngest sediment was the most diverse and was dominated by the phyla Actinobacteria and Proteobacteria In contrast, microbial diversity decreased dramatically in the older sediments, and anaerobic, spore-forming bacteria within Firmicutes became overwhelmingly dominant. In addition to the enrichment of sporulation-related genes, functional genes involved in anaerobic metabolic pathways such as fermentation, sulfate reduction, and methanogenesis were more abundant in the older sediments. Taken together, the predominance of spore-forming bacteria and associated anaerobic metabolism in the older sediments suggest that a subset of the original indigenous microbial community entrapped in the permafrost survived burial over geological time.IMPORTANCE Understanding the long-term survivability and associated metabolic traits of microorganisms in ancient permafrost frozen millions of years ago provides a unique window into the burial and preservation processes experienced in general by subsurface microorganisms in sedimentary deposits because of permafrost's hydrological isolation and exceptional DNA preservation. We employed aspartic acid racemization modeling and metagenomics to determine which microbial communities were metabolically active in the 1.1-Ma permafrost from northeastern Siberia. The simultaneous sequencing of extracellular and intracellular genomic DNA provided insight into the metabolic potential distinguishing extinct from extant microorganisms under frozen conditions over this time interval. This in-depth metagenomic sequencing advances our understanding of the microbial diversity and metabolic functions of extant microbiomes from early Pleistocene permafrost. Therefore, these findings extend our knowledge of the survivability of microbes in permafrost from 33,000 years to 1.1 Ma.
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Maslowska KH, Makiela‐Dzbenska K, Fijalkowska IJ. The SOS system: A complex and tightly regulated response to DNA damage. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:368-384. [PMID: 30447030 PMCID: PMC6590174 DOI: 10.1002/em.22267] [Citation(s) in RCA: 218] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/29/2018] [Accepted: 11/13/2018] [Indexed: 05/10/2023]
Abstract
Genomes of all living organisms are constantly threatened by endogenous and exogenous agents that challenge the chemical integrity of DNA. Most bacteria have evolved a coordinated response to DNA damage. In Escherichia coli, this inducible system is termed the SOS response. The SOS global regulatory network consists of multiple factors promoting the integrity of DNA as well as error-prone factors allowing for survival and continuous replication upon extensive DNA damage at the cost of elevated mutagenesis. Due to its mutagenic potential, the SOS response is subject to elaborate regulatory control involving not only transcriptional derepression, but also post-translational activation, and inhibition. This review summarizes current knowledge about the molecular mechanism of the SOS response induction and progression and its consequences for genome stability. Environ. Mol. Mutagen. 60:368-384, 2019. © 2018 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
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Affiliation(s)
- Katarzyna H. Maslowska
- Cancer Research Center of Marseille, CNRS, UMR7258Inserm, U1068; Institut Paoli‐Calmettes, Aix‐Marseille UniversityMarseilleFrance
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
| | | | - Iwona J. Fijalkowska
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
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28
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Saha T, Shukla K, Thakur RS, Desingu A, Nagaraju G. Mycobacterium tuberculosis UvrD1 and UvrD2 helicases unwind G-quadruplex DNA. FEBS J 2019; 286:2062-2086. [PMID: 30821905 DOI: 10.1111/febs.14798] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 01/07/2019] [Accepted: 02/28/2019] [Indexed: 01/31/2023]
Abstract
Unresolved G-quadruplex (G4) DNA secondary structures impede DNA replication and can lead to DNA breaks and to genome instability. Helicases are known to unwind G4 structures and thereby facilitate genome duplication. Escherichia coli UvrD is a multifunctional helicase that participates in DNA repair, recombination and replication. Previously, we had demonstrated a novel role of E. coli UvrD helicase in resolving G4 structures. Mycobacterium tuberculosis genome encodes two orthologs of E. coli UvrD helicase, UvrD1 and UvrD2. It is unclear whether UvrD1 or UvrD2 or both helicases unwind G4 DNA structures. Here, we demonstrate that M. tuberculosis UvrD1 and UvrD2 unwind G4 tetraplexes. Both helicases were proficient in resolving previously characterized tetramolecular G4 structures in an ATP hydrolysis and single-stranded 3'-tail-dependent manner. Notably, M. tuberculosis UvrD1 and UvrD2 were efficient in unwinding G4 structures derived from the potential G4 forming sequences present in the M. tuberculosis genome. These data suggest an extended role for M. tuberculosis UvrD1 and UvrD2 helicases in resolving G4 DNA structures and provide insights into the maintenance of genome integrity via G4 DNA resolution.
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Affiliation(s)
- Tias Saha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Kaustubh Shukla
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | - Ambika Desingu
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Ganesh Nagaraju
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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Ismail AM, Lee JS, Lee JY, Singh G, Dyer DW, Seto D, Chodosh J, Rajaiya J. Adenoviromics: Mining the Human Adenovirus Species D Genome. Front Microbiol 2018; 9:2178. [PMID: 30254627 PMCID: PMC6141750 DOI: 10.3389/fmicb.2018.02178] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/24/2018] [Indexed: 12/19/2022] Open
Abstract
Human adenovirus (HAdV) infections cause disease world-wide. Whole genome sequencing has now distinguished 90 distinct genotypes in 7 species (A-G). Over half of these 90 HAdVs fall within species D, with essentially all of the HAdV-D whole genome sequences generated in the last decade. Herein, we describe recent new findings made possible by mining of this expanded genome database, and propose future directions to elucidate new functional elements and new functions for previously known viral components.
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Affiliation(s)
- Ashrafali M Ismail
- Howe Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Ji Sun Lee
- Howe Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Jeong Yoon Lee
- Howe Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States.,Molecular Virology Laboratory, Korea Zoonosis Research Institute, Jeonbuk National University, Jeonju, South Korea
| | - Gurdeep Singh
- Howe Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - David W Dyer
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Donald Seto
- Bioinformatics and Computational Biology Program, School of Systems Biology, George Mason University, Manassas, VI, United States
| | - James Chodosh
- Howe Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Jaya Rajaiya
- Howe Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
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30
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Groom J, Chung D, Kim SK, Guss A, Westpheling J. Deletion of the Clostridium thermocellum recA gene reveals that it is required for thermophilic plasmid replication but not plasmid integration at homologous DNA sequences. J Ind Microbiol Biotechnol 2018; 45:753-763. [PMID: 29808293 PMCID: PMC6483729 DOI: 10.1007/s10295-018-2049-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/19/2018] [Indexed: 12/30/2022]
Abstract
A limitation to the engineering of cellulolytic thermophiles is the availability of functional, thermostable (≥ 60 °C) replicating plasmid vectors for rapid expression and testing of genes that provide improved or novel fuel molecule production pathways. A series of plasmid vectors for genetic manipulation of the cellulolytic thermophile Caldicellulosiruptor bescii has recently been extended to Clostridium thermocellum, another cellulolytic thermophile that very efficiently solubilizes plant biomass and produces ethanol. While the C. bescii pBAS2 replicon on these plasmids is thermostable, the use of homologous promoters, signal sequences and genes led to undesired integration into the bacterial chromosome, a result also observed with less thermostable replicating vectors. In an attempt to overcome undesired plasmid integration in C. thermocellum, a deletion of recA was constructed. As expected, C. thermocellum ∆recA showed impaired growth in chemically defined medium and an increased susceptibility to UV damage. Interestingly, we also found that recA is required for replication of the C. bescii thermophilic plasmid pBAS2 in C. thermocellum, but it is not required for replication of plasmid pNW33N. In addition, the C. thermocellum recA mutant retained the ability to integrate homologous DNA into the C. thermocellum chromosome. These data indicate that recA can be required for replication of certain plasmids, and that a recA-independent mechanism exists for the integration of homologous DNA into the C. thermocellum chromosome. Understanding thermophilic plasmid replication is not only important for engineering of these cellulolytic thermophiles, but also for developing genetic systems in similar new potentially useful non-model organisms.
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Affiliation(s)
- Joseph Groom
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA, 30602, USA
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98105, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Daehwan Chung
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO, 80401, USA
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Sun-Ki Kim
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA, 30602, USA
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Adam Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Janet Westpheling
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA, 30602, USA.
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA.
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA.
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Singh A. Guardians of the mycobacterial genome: A review on DNA repair systems in Mycobacterium tuberculosis. MICROBIOLOGY-SGM 2017; 163:1740-1758. [PMID: 29171825 DOI: 10.1099/mic.0.000578] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The genomic integrity of Mycobacterium tuberculosis is continuously threatened by the harsh survival conditions inside host macrophages, due to immune and antibiotic stresses. Faithful genome maintenance and repair must be accomplished under stress for the bacillus to survive in the host, necessitating a robust DNA repair system. The importance of DNA repair systems in pathogenesis is well established. Previous examination of the M. tuberculosis genome revealed homologues of almost all the major DNA repair systems, i.e. nucleotide excision repair (NER), base excision repair (BER), homologous recombination (HR) and non-homologous end joining (NHEJ). However, recent developments in the field have pointed to the presence of novel proteins and pathways in mycobacteria. Homologues of archeal mismatch repair proteins were recently reported in mycobacteria, a pathway previously thought to be absent. RecBCD, the major nuclease-helicase enzymes involved in HR in E. coli, were implicated in the single-strand annealing (SSA) pathway. Novel roles of archeo-eukaryotic primase (AEP) polymerases, previously thought to be exclusive to NHEJ, have been reported in BER. Many new proteins with a probable role in DNA repair have also been discovered. It is now realized that the DNA repair systems in M. tuberculosis are highly evolved and have redundant backup mechanisms to mend the damage. This review is an attempt to summarize our current understanding of the DNA repair systems in M. tuberculosis.
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Affiliation(s)
- Amandeep Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
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Ichimura K, Shimizu T, Matsumoto A, Hirai S, Yokoyama E, Takeuchi H, Yahiro K, Noda M. Nitric oxide-enhanced Shiga toxin production was regulated by Fur and RecA in enterohemorrhagic Escherichia coli O157. Microbiologyopen 2017; 6. [PMID: 28294553 PMCID: PMC5552940 DOI: 10.1002/mbo3.461] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/20/2017] [Accepted: 02/01/2017] [Indexed: 12/27/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) produces Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2). Nitric oxide (NO), which acts as an antimicrobial defense molecule, was found to enhance the production of Stx1 and Stx2 in EHEC under anaerobic conditions. Although EHEC O157 has two types of anaerobic NO reductase genes, an intact norV and a deleted norV, in the deleted norV‐type EHEC, a high concentration of NO (12–29 μmol/L, maximum steady‐state concentration) is required for enhanced Stx1 production and a low concentration of NO (~12 μmol/L, maximum steady‐state concentration) is sufficient for enhanced Stx2 production under anaerobic conditions. These results suggested that different concentration thresholds of NO elicit a discrete set of Stx1 and Stx2 production pathways. Moreover, the enhancement of Shiga toxin production in the intact norV‐type EHEC required treatment with a higher concentration of NO than was required for enhancement of Shiga toxin production in the deleted norV‐type EHEC, suggesting that the specific NorV type plays an important role in the level of enhancement of Shiga toxin production in response to NO. Finally, Fur derepression and RecA activation in EHEC were shown to participate in the NO‐enhanced Stx1 and Stx2 production, respectively.
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Affiliation(s)
- Kimitoshi Ichimura
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Takeshi Shimizu
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Akio Matsumoto
- Pharmacology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Shinichiro Hirai
- Division of Bacteriology, Chiba Prefectural Institute of Public Health, Chiba, Japan
| | - Eiji Yokoyama
- Division of Bacteriology, Chiba Prefectural Institute of Public Health, Chiba, Japan
| | - Hiroki Takeuchi
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Kinnosuke Yahiro
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Masatoshi Noda
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan
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Korolev S. Advances in structural studies of recombination mediator proteins. Biophys Chem 2016; 225:27-37. [PMID: 27974172 DOI: 10.1016/j.bpc.2016.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/01/2016] [Accepted: 12/01/2016] [Indexed: 12/25/2022]
Abstract
Recombination mediator proteins (RMPs) are critical for genome integrity in all organisms. They include phage UvsY, prokaryotic RecF, -O, -R (RecFOR) and eukaryotic Rad52, Breast Cancer susceptibility 2 (BRCA2) and Partner and localizer of BRCA2 (PALB2) proteins. BRCA2 and PALB2 are tumor suppressors implicated in cancer. RMPs regulate binding of RecA-like recombinases to sites of DNA damage to initiate the most efficient non-mutagenic repair of broken chromosome and other deleterious DNA lesions. Mechanistically, RMPs stimulate a single-stranded DNA (ssDNA) hand-off from ssDNA binding proteins (ssbs) such as gp32, SSB and RPA, to recombinases, activating DNA repair only at the time and site of the damage event. This review summarizes structural studies of RMPs and their implications for understanding mechanism and function. Comparative analysis of RMPs is complicated due to their convergent evolution. In contrast to the evolutionary conserved ssbs and recombinases, RMPs are extremely diverse in sequence and structure. Structural studies are particularly important in such cases to reveal common features of the entire family and specific features of regulatory mechanisms for each member. All RMPs are characterized by specific DNA-binding domains and include variable protein interaction motifs. The complexity of such RMPs corresponds to the ever-growing number of DNA metabolism events they participate in under normal and pathological conditions and requires additional comprehensive structure-functional studies.
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Affiliation(s)
- S Korolev
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 S Grand Blvd., St. Louis, MO 63104, USA.
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34
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Odahara M, Kobayashi Y, Shikanai T, Nishimura Y. Dynamic Interplay between Nucleoid Segregation and Genome Integrity in Chlamydomonas Chloroplasts. PLANT PHYSIOLOGY 2016; 172:2337-2346. [PMID: 27756821 PMCID: PMC5129732 DOI: 10.1104/pp.16.01533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 10/13/2016] [Indexed: 06/06/2023]
Abstract
The chloroplast (cp) genome is organized as nucleoids that are dispersed throughout the cp stroma. Previously, a cp homolog of bacterial recombinase RecA (cpRECA) was shown to be involved in the maintenance of cp genome integrity by repairing damaged chloroplast DNA and by suppressing aberrant recombination between short dispersed repeats in the moss Physcomitrella patens Here, overexpression and knockdown analysis of cpRECA in the green alga Chlamydomonas reinhardtii revealed that cpRECA was involved in cp nucleoid dynamics as well as having a role in maintaining cp genome integrity. Overexpression of cpRECA tagged with yellow fluorescent protein or hemagglutinin resulted in the formation of giant filamentous structures that colocalized exclusively to chloroplast DNA and cpRECA localized to cp nucleoids in a heterogenous manner. Knockdown of cpRECA led to a significant reduction in cp nucleoid number that was accompanied by nucleoid enlargement. This phenotype resembled those of gyrase inhibitor-treated cells and monokaryotic chloroplast mutant cells and suggested that cpRECA was involved in organizing cp nucleoid dynamics. The cp genome also was destabilized by induced recombination between short dispersed repeats in cpRECA-knockdown cells and gyrase inhibitor-treated cells. Taken together, these results suggest that cpRECA and gyrase are both involved in nucleoid dynamics and the maintenance of genome integrity and that the mechanisms underlying these processes may be intimately related in C. reinhardtii cps.
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Affiliation(s)
- Masaki Odahara
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (M.O., Y.K., T.S., Y.N.); and
- Department of Life Science, College of Science, Rikkyo (St. Paul's) University, Toshima-ku, Tokyo 171-8501, Japan (M.O.)
| | - Yusuke Kobayashi
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (M.O., Y.K., T.S., Y.N.); and
- Department of Life Science, College of Science, Rikkyo (St. Paul's) University, Toshima-ku, Tokyo 171-8501, Japan (M.O.)
| | - Toshiharu Shikanai
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (M.O., Y.K., T.S., Y.N.); and
- Department of Life Science, College of Science, Rikkyo (St. Paul's) University, Toshima-ku, Tokyo 171-8501, Japan (M.O.)
| | - Yoshiki Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (M.O., Y.K., T.S., Y.N.); and
- Department of Life Science, College of Science, Rikkyo (St. Paul's) University, Toshima-ku, Tokyo 171-8501, Japan (M.O.)
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35
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Banda S, Tiwari PB, Darici Y, Tse-Dinh YC. Investigating direct interaction between Escherichia coli topoisomerase I and RecA. Gene 2016; 585:65-70. [PMID: 27001450 PMCID: PMC4838544 DOI: 10.1016/j.gene.2016.03.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 03/12/2016] [Indexed: 01/14/2023]
Abstract
Protein-protein interactions are of special importance in cellular processes, including replication, transcription, recombination, and repair. Escherichia coli topoisomerase I (EcTOP1) is primarily involved in the relaxation of negative DNA supercoiling. E. coli RecA, the key protein for homologous recombination and SOS DNA-damage response, has been shown to stimulate the relaxation activity of EcTOP1. The evidence for their direct protein-protein interaction has not been previously established. We report here the direct physical interaction between E. coli RecA and topoisomerase I. We demonstrated the RecA-topoisomerase I interaction via pull-down assays, and surface plasmon resonance measurements. Molecular docking supports the observation that the interaction involves the topoisomerase I N-terminal domains that form the active site. Our results from pull-down assays showed that ATP, although not required, enhances the RecA-EcTOP1 interaction. We propose that E. coli RecA physically interacts with topoisomerase I to modulate the chromosomal DNA supercoiling.
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Affiliation(s)
- Srikanth Banda
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA
| | | | - Yesim Darici
- Department of Physics, Florida International University, Miami, Florida, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA
- Biomolecular Sciences Institute, Florida International University, Miami, Florida, USA
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Singh A, Bhagavat R, Vijayan M, Chandra N. A comparative analysis of the DNA recombination repair pathway in mycobacterial genomes. Tuberculosis (Edinb) 2016; 99:109-119. [PMID: 27450012 DOI: 10.1016/j.tube.2016.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 04/19/2016] [Accepted: 04/28/2016] [Indexed: 10/21/2022]
Abstract
In prokaryotes, repair by homologous recombination provides a major means to reinstate the genetic information lost in DNA damage. Recombination repair pathway in mycobacteria has multiple differences as compared to that in Escherichia coli. Of about 20 proteins known to be involved in the pathway, a set of 9 proteins, namely, RecF, RecO, RecR, RecA, SSBa, RuvA, RuvB and RuvC was found to be indispensable among the 43 mycobacterial strains. A domain level analysis indicated that most domains involved in recombination repair are unique to these proteins and are present as single copies in the genomes. Synteny analysis reveals that the gene order of proteins involved in the pathway is not conserved, suggesting that they may be regulated differently in different species. Sequence conservation among the same protein from different strains suggests the importance of RecO-RecA and RecFOR-RecA presynaptic pathways in the repair of double strand-breaks and single strand-breaks respectively. New annotations obtained from the analysis, include identification of a protein with a probable Holliday junction binding role present in 41 mycobacterial genomes and that of a RecB-like nuclease, containing a cas4 domain, present in 42 genomes. New insights into the binding of small molecules to the relevant proteins are provided by binding pocket analysis using three dimensional structural models. Analysis of the various features of the recombination repair pathway, presented here, is likely to provide a framework for further exploring stress response and emergence of drug resistance in mycobacteria.
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Affiliation(s)
- Amandeep Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Raghu Bhagavat
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - M Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Nagasuma Chandra
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, Karnataka, India.
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Bakhlanova IV, Dudkina AV, Wood EA, Lanzov VA, Cox MM, Baitin DM. DNA Metabolism in Balance: Rapid Loss of a RecA-Based Hyperrec Phenotype. PLoS One 2016; 11:e0154137. [PMID: 27124470 PMCID: PMC4849656 DOI: 10.1371/journal.pone.0154137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/09/2016] [Indexed: 12/04/2022] Open
Abstract
The RecA recombinase of Escherichia coli has not evolved to optimally promote DNA pairing and strand exchange, the key processes of recombinational DNA repair. Instead, the recombinase function of RecA protein represents an evolutionary compromise between necessary levels of recombinational DNA repair and the potentially deleterious consequences of RecA functionality. A RecA variant, RecA D112R, promotes conjugational recombination at substantially enhanced levels. However, expression of the D112R RecA protein in E. coli results in a reduction in cell growth rates. This report documents the consequences of the substantial selective pressure associated with the RecA-mediated hyperrec phenotype. With continuous growth, the deleterious effects of RecA D112R, along with the observed enhancements in conjugational recombination, are lost over the course of 70 cell generations. The suppression reflects a decline in RecA D112R expression, associated primarily with a deletion in the gene promoter or chromosomal mutations that decrease plasmid copy number. The deleterious effects of RecA D112R on cell growth can also be negated by over-expression of the RecX protein from Neisseria gonorrhoeae. The effects of the RecX proteins in vivo parallel the effects of the same proteins on RecA D112R filaments in vitro. The results indicate that the toxicity of RecA D112R is due to its persistent binding to duplex genomic DNA, creating barriers for other processes in DNA metabolism. A substantial selective pressure is generated to suppress the resulting barrier to growth.
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Affiliation(s)
- Irina V. Bakhlanova
- Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, 188300, Russia
- Peter the Great St. Petersburg Polytechnic University, Saint-Petersburg, 195251, Russia
| | - Alexandra V. Dudkina
- Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, 188300, Russia
| | - Elizabeth A. Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706–1544, United States of America
| | - Vladislav A. Lanzov
- Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, 188300, Russia
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706–1544, United States of America
| | - Dmitry M. Baitin
- Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, 188300, Russia
- Peter the Great St. Petersburg Polytechnic University, Saint-Petersburg, 195251, Russia
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Bakhlanova IV, Baitin DM. Deinococcus radiodurans RecX and Escherichia coli RecX proteins are capable to replace each other in vivo and in vitro. RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416030030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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SOS System Induction Inhibits the Assembly of Chemoreceptor Signaling Clusters in Salmonella enterica. PLoS One 2016; 11:e0146685. [PMID: 26784887 PMCID: PMC4718596 DOI: 10.1371/journal.pone.0146685] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/21/2015] [Indexed: 01/08/2023] Open
Abstract
Swarming, a flagellar-driven multicellular form of motility, is associated with bacterial virulence and increased antibiotic resistance. In this work we demonstrate that activation of the SOS response reversibly inhibits swarming motility by preventing the assembly of chemoreceptor-signaling polar arrays. We also show that an increase in the concentration of the RecA protein, generated by SOS system activation, rather than another function of this genetic network impairs chemoreceptor polar cluster formation. Our data provide evidence that the molecular balance between RecA and CheW proteins is crucial to allow polar cluster formation in Salmonella enterica cells. Thus, activation of the SOS response by the presence of a DNA-injuring compound increases the RecA concentration, thereby disturbing the equilibrium between RecA and CheW and resulting in the cessation of swarming. Nevertheless, when the DNA-damage decreases and the SOS response is no longer activated, basal RecA levels and thus polar cluster assembly are reestablished. These results clearly show that bacterial populations moving over surfaces make use of specific mechanisms to avoid contact with DNA-damaging compounds.
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Ronayne EA, Wan YCS, Boudreau BA, Landick R, Cox MM. P1 Ref Endonuclease: A Molecular Mechanism for Phage-Enhanced Antibiotic Lethality. PLoS Genet 2016; 12:e1005797. [PMID: 26765929 PMCID: PMC4713147 DOI: 10.1371/journal.pgen.1005797] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 12/19/2015] [Indexed: 12/11/2022] Open
Abstract
Ref is an HNH superfamily endonuclease that only cleaves DNA to which RecA protein is bound. The enigmatic physiological function of this unusual enzyme is defined here. Lysogenization by bacteriophage P1 renders E. coli more sensitive to the DNA-damaging antibiotic ciprofloxacin, an example of a phenomenon termed phage-antibiotic synergy (PAS). The complementary effect of phage P1 is uniquely traced to the P1-encoded gene ref. Ref is a P1 function that amplifies the lytic cycle under conditions when the bacterial SOS response is induced due to DNA damage. The effect of Ref is multifaceted. DNA binding by Ref interferes with normal DNA metabolism, and the nuclease activity of Ref enhances genome degradation. Ref also inhibits cell division independently of the SOS response. Ref gene expression is toxic to E. coli in the absence of other P1 functions, both alone and in combination with antibiotics. The RecA proteins of human pathogens Neisseria gonorrhoeae and Staphylococcus aureus serve as cofactors for Ref-mediated DNA cleavage. Ref is especially toxic during the bacterial SOS response and the limited growth of stationary phase cultures, targeting aspects of bacterial physiology that are closely associated with the development of bacterial pathogen persistence.
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Affiliation(s)
- Erin A. Ronayne
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Y. C. Serena Wan
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Beth A. Boudreau
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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41
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Odahara M, Inouye T, Nishimura Y, Sekine Y. RECA plays a dual role in the maintenance of chloroplast genome stability in Physcomitrella patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 84:516-526. [PMID: 26340426 DOI: 10.1111/tpj.13017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 08/27/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
Chloroplast DNA (cpDNA) encodes essential genes for chloroplast functions, including photosynthesis. Homologous recombination occurs frequently in cpDNA; however, its significance and underlying mechanism remain poorly understood. In this study, we analyzed the role of a nuclear-encoded chloroplast-localized homolog of RecA recombinase, which is a key factor in homologous recombination in bacteria, in the moss Physcomitrella patens. Complete knockout (KO) of the P. patens chloroplast RecA homolog RECA2 caused a modest growth defect and conferred sensitivity to methyl methanesulfonate and UV. The KO mutant exhibited low recovery of cpDNA from methyl methanesulfonate damage, suggesting that RECA2 knockout impairs repair of damaged cpDNA. The RECA2 KO mutant also exhibited reduced cpDNA copy number and an elevated level of cpDNA molecule resulting from aberrant recombination between short dispersed repeats (13-63 bp), indicating that the RECA2 KO chloroplast genome was destabilized. Taken together, these data suggest a dual role for RECA2 in the maintenance of chloroplast genome stability: RECA2 suppresses aberrant recombination between short dispersed repeats and promotes repair of damaged DNA.
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Affiliation(s)
- Masaki Odahara
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kita-Shirakawa, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Takayuki Inouye
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Yoshiki Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kita-Shirakawa, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yasuhiko Sekine
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
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42
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Thakur RS, Basavaraju S, Khanduja JS, Muniyappa K, Nagaraju G. Mycobacterium tuberculosis RecG protein but not RuvAB or RecA protein is efficient at remodeling the stalled replication forks: implications for multiple mechanisms of replication restart in mycobacteria. J Biol Chem 2015; 290:24119-39. [PMID: 26276393 DOI: 10.1074/jbc.m115.671164] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 11/06/2022] Open
Abstract
Aberrant DNA replication, defects in the protection, and restart of stalled replication forks are major causes of genome instability in all organisms. Replication fork reversal is emerging as an evolutionarily conserved physiological response for restart of stalled forks. Escherichia coli RecG, RuvAB, and RecA proteins have been shown to reverse the model replication fork structures in vitro. However, the pathways and the mechanisms by which Mycobacterium tuberculosis, a slow growing human pathogen, responds to different types of replication stress and DNA damage are unclear. Here, we show that M. tuberculosis RecG rescues E. coli ΔrecG cells from replicative stress. The purified M. tuberculosis RecG (MtRecG) and RuvAB (MtRuvAB) proteins catalyze fork reversal of model replication fork structures with and without a leading strand single-stranded DNA gap. Interestingly, single-stranded DNA-binding protein suppresses the MtRecG- and MtRuvAB-mediated fork reversal with substrates that contain lagging strand gap. Notably, our comparative studies with fork structures containing template damage and template switching mechanism of lesion bypass reveal that MtRecG but not MtRuvAB or MtRecA is proficient in driving the fork reversal. Finally, unlike MtRuvAB, we find that MtRecG drives efficient reversal of forks when fork structures are tightly bound by protein. These results provide direct evidence and valuable insights into the underlying mechanism of MtRecG-catalyzed replication fork remodeling and restart pathways in vivo.
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Affiliation(s)
- Roshan Singh Thakur
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Shivakumar Basavaraju
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Jasbeer Singh Khanduja
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - K Muniyappa
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Ganesh Nagaraju
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
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Kingston AW, Roussel-Rossin C, Dupont C, Raleigh EA. Novel recA-Independent Horizontal Gene Transfer in Escherichia coli K-12. PLoS One 2015; 10:e0130813. [PMID: 26162088 PMCID: PMC4498929 DOI: 10.1371/journal.pone.0130813] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 05/27/2015] [Indexed: 01/19/2023] Open
Abstract
In bacteria, mechanisms that incorporate DNA into a genome without strand-transfer proteins such as RecA play a major role in generating novelty by horizontal gene transfer. We describe a new illegitimate recombination event in Escherichia coli K-12: RecA-independent homologous replacements, with very large (megabase-length) donor patches replacing recipient DNA. A previously uncharacterized gene (yjiP) increases the frequency of RecA-independent replacement recombination. To show this, we used conjugal DNA transfer, combining a classical conjugation donor, HfrH, with modern genome engineering methods and whole genome sequencing analysis to enable interrogation of genetic dependence of integration mechanisms and characterization of recombination products. As in classical experiments, genomic DNA transfer begins at a unique position in the donor, entering the recipient via conjugation; antibiotic resistance markers are then used to select recombinant progeny. Different configurations of this system were used to compare known mechanisms for stable DNA incorporation, including homologous recombination, F'-plasmid formation, and genome duplication. A genome island of interest known as the immigration control region was specifically replaced in a minority of recombinants, at a frequency of 3 X 10(-12) CFU/recipient per hour.
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Affiliation(s)
- Anthony W. Kingston
- New England Biolabs, Ipswich, Massachusetts, 01938, United States of America
| | | | - Claire Dupont
- New England Biolabs, Ipswich, Massachusetts, 01938, United States of America
| | - Elisabeth A. Raleigh
- New England Biolabs, Ipswich, Massachusetts, 01938, United States of America
- * E-mail:
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44
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Interactions and Localization of Escherichia coli Error-Prone DNA Polymerase IV after DNA Damage. J Bacteriol 2015; 197:2792-809. [PMID: 26100038 DOI: 10.1128/jb.00101-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 06/11/2015] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Escherichia coli's DNA polymerase IV (Pol IV/DinB), a member of the Y family of error-prone polymerases, is induced during the SOS response to DNA damage and is responsible for translesion bypass and adaptive (stress-induced) mutation. In this study, the localization of Pol IV after DNA damage was followed using fluorescent fusions. After exposure of E. coli to DNA-damaging agents, fluorescently tagged Pol IV localized to the nucleoid as foci. Stepwise photobleaching indicated ∼60% of the foci consisted of three Pol IV molecules, while ∼40% consisted of six Pol IV molecules. Fluorescently tagged Rep, a replication accessory DNA helicase, was recruited to the Pol IV foci after DNA damage, suggesting that the in vitro interaction between Rep and Pol IV reported previously also occurs in vivo. Fluorescently tagged RecA also formed foci after DNA damage, and Pol IV localized to them. To investigate if Pol IV localizes to double-strand breaks (DSBs), an I-SceI endonuclease-mediated DSB was introduced close to a fluorescently labeled LacO array on the chromosome. After DSB induction, Pol IV localized to the DSB site in ∼70% of SOS-induced cells. RecA also formed foci at the DSB sites, and Pol IV localized to the RecA foci. These results suggest that Pol IV interacts with RecA in vivo and is recruited to sites of DSBs to aid in the restoration of DNA replication. IMPORTANCE DNA polymerase IV (Pol IV/DinB) is an error-prone DNA polymerase capable of bypassing DNA lesions and aiding in the restart of stalled replication forks. In this work, we demonstrate in vivo localization of fluorescently tagged Pol IV to the nucleoid after DNA damage and to DNA double-strand breaks. We show colocalization of Pol IV with two proteins: Rep DNA helicase, which participates in replication, and RecA, which catalyzes recombinational repair of stalled replication forks. Time course experiments suggest that Pol IV recruits Rep and that RecA recruits Pol IV. These findings provide in vivo evidence that Pol IV aids in maintaining genomic stability not only by bypassing DNA lesions but also by participating in the restoration of stalled replication forks.
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45
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Merrikh CN, Brewer BJ, Merrikh H. The B. subtilis Accessory Helicase PcrA Facilitates DNA Replication through Transcription Units. PLoS Genet 2015; 11:e1005289. [PMID: 26070154 PMCID: PMC4466434 DOI: 10.1371/journal.pgen.1005289] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 05/18/2015] [Indexed: 11/18/2022] Open
Abstract
In bacteria the concurrence of DNA replication and transcription leads to potentially deleterious encounters between the two machineries, which can occur in either the head-on (lagging strand genes) or co-directional (leading strand genes) orientations. These conflicts lead to replication fork stalling and can destabilize the genome. Both eukaryotic and prokaryotic cells possess resolution factors that reduce the severity of these encounters. Though Escherichia coli accessory helicases have been implicated in the mitigation of head-on conflicts, direct evidence of these proteins mitigating co-directional conflicts is lacking. Furthermore, the endogenous chromosomal regions where these helicases act, and the mechanism of recruitment, have not been identified. We show that the essential Bacillus subtilis accessory helicase PcrA aids replication progression through protein coding genes of both head-on and co-directional orientations, as well as rRNA and tRNA genes. ChIP-Seq experiments show that co-directional conflicts at highly transcribed rRNA, tRNA, and head-on protein coding genes are major targets of PcrA activity on the chromosome. Partial depletion of PcrA renders cells extremely sensitive to head-on conflicts, linking the essential function of PcrA to conflict resolution. Furthermore, ablating PcrA’s ATPase/helicase activity simultaneously increases its association with conflict regions, while incapacitating its ability to mitigate conflicts, and leads to cell death. In contrast, disruption of PcrA’s C-terminal RNA polymerase interaction domain does not impact its ability to mitigate conflicts between replication and transcription, its association with conflict regions, or cell survival. Altogether, this work establishes PcrA as an essential factor involved in mitigating transcription-replication conflicts and identifies chromosomal regions where it routinely acts. As both conflicts and accessory helicases are found in all domains of life, these results are broadly relevant. In bacteria the concurrence of DNA replication and transcription leads to potentially deleterious encounters between the two machineries. These encounters can destabilize the genome and lead to mutations. Both eukaryotic and prokaryotic cells possess conflict resolution factors that reduce the detrimental effects of these collisions. In this study we show that without the essential Bacillus subtilis accessory DNA helicase, PcrA, the replication machinery slows down at certain regions of the chromosome in a transcription-dependent manner. PcrA is essential to life but incomplete depletion of PcrA only partially inhibits cell survival. We find that, under these conditions, partial survival defects are significantly exacerbated in the presence of a single severe conflict. In summary our work identifies a high degree of conservation for accessory helicase function in conflict resolution, directly establishes PcrA’s role in co-directional conflict resolution, and maps the natural chromosomal regions where such activities are routinely needed. Because both conflicts and accessory helicases are found in all domains of life, the results of this work are broadly relevant.
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Affiliation(s)
- Christopher N. Merrikh
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Bonita J. Brewer
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Houra Merrikh
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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46
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Kim T, Chitteni-Pattu S, Cox BL, Wood EA, Sandler SJ, Cox MM. Directed Evolution of RecA Variants with Enhanced Capacity for Conjugational Recombination. PLoS Genet 2015; 11:e1005278. [PMID: 26047498 PMCID: PMC4457935 DOI: 10.1371/journal.pgen.1005278] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 05/13/2015] [Indexed: 11/18/2022] Open
Abstract
The recombination activity of Escherichia coli (E. coli) RecA protein reflects an evolutionary balance between the positive and potentially deleterious effects of recombination. We have perturbed that balance, generating RecA variants exhibiting improved recombination functionality via random mutagenesis followed by directed evolution for enhanced function in conjugation. A recA gene segment encoding a 59 residue segment of the protein (Val79-Ala137), encompassing an extensive subunit-subunit interface region, was subjected to degenerate oligonucleotide-mediated mutagenesis. An iterative selection process generated at least 18 recA gene variants capable of producing a higher yield of transconjugants. Three of the variant proteins, RecA I102L, RecA V79L and RecA E86G/C90G were characterized based on their prominence. Relative to wild type RecA, the selected RecA variants exhibited faster rates of ATP hydrolysis, more rapid displacement of SSB, decreased inhibition by the RecX regulator protein, and in general displayed a greater persistence on DNA. The enhancement in conjugational function comes at the price of a measurable RecA-mediated cellular growth deficiency. Persistent DNA binding represents a barrier to other processes of DNA metabolism in vivo. The growth deficiency is alleviated by expression of the functionally robust RecX protein from Neisseria gonorrhoeae. RecA filaments can be a barrier to processes like replication and transcription. RecA regulation by RecX protein is important in maintaining an optimal balance between recombination and other aspects of DNA metabolism. The genetic recombination systems of bacteria have not evolved for optimal enzymatic function. As recombination and recombination systems can have deleterious effects, these systems have evolved sufficient function to repair a level of DNA double strand breaks typically encountered during replication and cell division. However, maintenance of genome stability requires a proper balance between all aspects of DNA metabolism. A substantial increase in recombinase function is possible, but it comes with a cellular cost. Here, we use a kind of directed evolution to generate variants of the Escherichia coli RecA protein with an enhanced capacity to promote conjugational recombination. The mutations all occur within a targeted 59 amino acid segment of the protein, encompassing a significant part of the subunit-subunit interface. The RecA variants exhibit a range of altered activities. In general, the mutations appear to increase RecA protein persistence as filaments formed on DNA creating barriers to DNA replication and/or transcription. The barriers can be eliminated via expression of more robust forms of a RecA regulator, the RecX protein. The results elucidate an evolutionary compromise between the beneficial and deleterious effects of recombination.
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Affiliation(s)
- Taejin Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Sindhu Chitteni-Pattu
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Benjamin L. Cox
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Elizabeth A. Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Steven J. Sandler
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts, United States of America
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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47
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Laurenceau R, Krasteva PV, Diallo A, Ouarti S, Duchateau M, Malosse C, Chamot-Rooke J, Fronzes R. Conserved Streptococcus pneumoniae spirosomes suggest a single type of transformation pilus in competence. PLoS Pathog 2015; 11:e1004835. [PMID: 25876066 PMCID: PMC4398557 DOI: 10.1371/journal.ppat.1004835] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 03/26/2015] [Indexed: 11/18/2022] Open
Abstract
The success of S. pneumoniae as a major human pathogen is largely due to its remarkable genomic plasticity, allowing efficient escape from antimicrobials action and host immune response. Natural transformation, or the active uptake and chromosomal integration of exogenous DNA during the transitory differentiated state competence, is the main mechanism for horizontal gene transfer and genomic makeover in pneumococci. Although transforming DNA has been proposed to be captured by Type 4 pili (T4P) in Gram-negative bacteria, and a competence-inducible comG operon encoding proteins homologous to T4P-biogenesis components is present in transformable Gram-positive bacteria, a prevailing hypothesis has been that S. pneumoniae assembles only short pseudopili to destabilize the cell wall for DNA entry. We recently identified a micrometer-sized T4P-like pilus on competent pneumococci, which likely serves as initial DNA receptor. A subsequent study, however, visualized a different structure--short, 'plaited' polymers--released in the medium of competent S. pneumoniae. Biochemical observation of concurrent pilin secretion led the authors to propose that the 'plaited' structures correspond to transformation pili acting as peptidoglycan drills that leave DNA entry pores upon secretion. Here we show that the 'plaited' filaments are not related to natural transformation as they are released by non-competent pneumococci, as well as by cells with disrupted pilus biogenesis components. Combining electron microscopy visualization with structural, biochemical and proteomic analyses, we further identify the 'plaited' polymers as spirosomes: macromolecular assemblies of the fermentative acetaldehyde-alcohol dehydrogenase enzyme AdhE that is well conserved in a broad range of Gram-positive and Gram-negative bacteria.
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Affiliation(s)
- Raphaël Laurenceau
- Unité G5 Biologie Structurale de la Sécrétion Bactérienne, Institut Pasteur, Paris, France
- UMR 3528, CNRS, Institut Pasteur, Paris, France
| | - Petya V. Krasteva
- Unité G5 Biologie Structurale de la Sécrétion Bactérienne, Institut Pasteur, Paris, France
- UMR 3528, CNRS, Institut Pasteur, Paris, France
- * E-mail: (PVK); (RF)
| | - Amy Diallo
- Unité G5 Biologie Structurale de la Sécrétion Bactérienne, Institut Pasteur, Paris, France
- UMR 3528, CNRS, Institut Pasteur, Paris, France
| | - Sahra Ouarti
- Unité G5 Biologie Structurale de la Sécrétion Bactérienne, Institut Pasteur, Paris, France
- UMR 3528, CNRS, Institut Pasteur, Paris, France
| | - Magalie Duchateau
- UMR 3528, CNRS, Institut Pasteur, Paris, France
- Spectrométrie de Masse Structurale et Protéomique, Institut Pasteur, Paris, France
- Plate-Forme de Protéomique, Institut Pasteur, Paris, France
| | - Christian Malosse
- UMR 3528, CNRS, Institut Pasteur, Paris, France
- Spectrométrie de Masse Structurale et Protéomique, Institut Pasteur, Paris, France
- Plate-Forme de Protéomique, Institut Pasteur, Paris, France
| | - Julia Chamot-Rooke
- UMR 3528, CNRS, Institut Pasteur, Paris, France
- Spectrométrie de Masse Structurale et Protéomique, Institut Pasteur, Paris, France
- Plate-Forme de Protéomique, Institut Pasteur, Paris, France
| | - Rémi Fronzes
- Unité G5 Biologie Structurale de la Sécrétion Bactérienne, Institut Pasteur, Paris, France
- UMR 3528, CNRS, Institut Pasteur, Paris, France
- * E-mail: (PVK); (RF)
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48
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Morrical SW. DNA-pairing and annealing processes in homologous recombination and homology-directed repair. Cold Spring Harb Perspect Biol 2015; 7:a016444. [PMID: 25646379 DOI: 10.1101/cshperspect.a016444] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The formation of heteroduplex DNA is a central step in the exchange of DNA sequences via homologous recombination, and in the accurate repair of broken chromosomes via homology-directed repair pathways. In cells, heteroduplex DNA largely arises through the activities of recombination proteins that promote DNA-pairing and annealing reactions. Classes of proteins involved in pairing and annealing include RecA-family DNA-pairing proteins, single-stranded DNA (ssDNA)-binding proteins, recombination mediator proteins, annealing proteins, and nucleases. This review explores the properties of these pairing and annealing proteins, and highlights their roles in complex recombination processes including the double Holliday junction (DhJ) formation, synthesis-dependent strand annealing, and single-strand annealing pathways--DNA transactions that are critical both for genome stability in individual organisms and for the evolution of species.
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Affiliation(s)
- Scott W Morrical
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405
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49
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Chen SH, Byrne RT, Wood EA, Cox MM. Escherichia coli radD (yejH) gene: a novel function involved in radiation resistance and double-strand break repair. Mol Microbiol 2015; 95:754-68. [PMID: 25425430 DOI: 10.1111/mmi.12885] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2014] [Indexed: 11/28/2022]
Abstract
A transposon insertion screen implicated the yejH gene in the repair of ionizing radiation-induced damage. The yejH gene, which exhibits significant homology to the human transcription-coupled DNA repair gene XPB, is involved in the repair of double-strand DNA breaks. Deletion of yejH significantly sensitized cells to agents that cause double-strand breaks (ionizing radiation, UV radiation, ciprofloxacin). In addition, deletion of both yejH and radA hypersensitized the cells to ionizing radiation, UV and ciprofloxacin damage, indicating that these two genes have complementary repair functions. The ΔyejH ΔradA double deletion also showed a substantial decline in viability following an induced double-strand DNA break, of a magnitude comparable with the defect measured when the recA, recB, recG or priA genes are deleted. The ATPase activity and C-terminal zinc finger motif of yejH play an important role in its repair function, as targeted mutant alleles of yejH did not rescue sensitivity. We propose that yejH be renamed radD, reflecting its role in the DNA repair of radiation damage.
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Affiliation(s)
- Stefanie H Chen
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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Li L, Chen Z, Ding X, Shan Z, Liu L, Guo J. Deep sequencing analysis of the Kineococcus radiotolerans transcriptome in response to ionizing radiation. Microbiol Res 2014; 170:248-54. [PMID: 25467197 DOI: 10.1016/j.micres.2014.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 10/07/2014] [Accepted: 10/23/2014] [Indexed: 10/24/2022]
Abstract
Kineococcus radiotolerans is a gram-positive, radiation-resistant bacterium that was isolated from a radioactive environment. The synergy of several groups of genes is thought to contribute to the radio-resistance of this species of bacteria. Sequencing of the transcriptome, RNA sequencing (RNA-seq), using deep sequencing technology can reveal the genes that are differentially expressed in response to radiation in this bacterial strain. In this study, the transcriptomes of two samples (with and without irradiation treatment) were sequencing by deep sequencing technology. After the bioinformatics process, 143 genes were screened out by the differential expression (DE) analysis. In all 143 differentially expressed genes, 20 genes were annotated to be related to the radio-resistance based on the cluster analysis by the cluster of orthologous groups of proteins (COG) annotation which were validated by the quantitative RT-PCR. The pathway analysis revealed that these 20 validated genes were related to DNA damage repair, including recA, ruvA and ruvB, which were considered to be the key genes in DNA damage repair. This study provides the foundation to investigate the regulatory mechanism of these genes.
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Affiliation(s)
- Lufeng Li
- College of Life Sciences, Zhejiang Sci-Tech University, No.2 Road, Xiasha, Hangzhou, Zhejiang, PR China.
| | - Zhouwei Chen
- College of Life Sciences, Zhejiang Sci-Tech University, No.2 Road, Xiasha, Hangzhou, Zhejiang, PR China.
| | - Xianfeng Ding
- College of Life Sciences, Zhejiang Sci-Tech University, No.2 Road, Xiasha, Hangzhou, Zhejiang, PR China.
| | - Zhan Shan
- College of Life Sciences, Zhejiang Sci-Tech University, No.2 Road, Xiasha, Hangzhou, Zhejiang, PR China.
| | - Lili Liu
- College of Life Sciences, Zhejiang Sci-Tech University, No.2 Road, Xiasha, Hangzhou, Zhejiang, PR China.
| | - Jiangfeng Guo
- College of Life Sciences, Zhejiang Sci-Tech University, No.2 Road, Xiasha, Hangzhou, Zhejiang, PR China.
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