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Ma G, Lin T, Cao P, Oger P, Dong K, Miao L, Zhang L. Biochemical characterization and mutational analysis of the NurA protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5. Res Microbiol 2024; 175:104189. [PMID: 38403006 DOI: 10.1016/j.resmic.2024.104189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/26/2024] [Accepted: 02/20/2024] [Indexed: 02/27/2024]
Abstract
Archaeal NurA protein plays a key role in producing 3'-single stranded DNA used for homologous recombination repair, together with HerA, Mre11, and Rad50. Herein, we describe biochemical characteristics and roles of key amino acid residues of the NurA protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 (Tba-NurA). Tba-NurA possesses 5'-3' exonuclease activity for degrading DNA, displaying maximum efficiency at 45 °C-65 °C and at pH 8.0 in the presence of Mn2+. The thermostable Tba-NurA also possesses endonuclease activity capable of nicking plasmid DNA and circular ssDNA. Mutational data demonstrate that residue D49 of Tba-NurA is essential for exonuclease activity and is involved in binding ssDNA since the D49A mutant lacked exonuclease activity and reduced ssDNA binding. The R96A and R129A mutants had no detectable dsDNA binding, suggesting that residues R96 and R129 are important for binding dsDNA. The abolished degradation activity and reduced dsDNA binding of the D120A mutant suggest that residue D120 is essential for degradation activity and dsDNA binding. Additionally, residues Y392 and H400 are important for exonuclease activity since these mutations resulted in exonuclease activity loss. To our knowledge, it is the first report on biochemical characterization and mutational analysis of the NurA protein from Thermococcus.
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Affiliation(s)
- Guangyu Ma
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Tan Lin
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Peng Cao
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China
| | - Philippe Oger
- Université de Lyon, INSA de Lyon, CNRS UMR, 5240 Lyon, France
| | - Kunming Dong
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Li Miao
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Likui Zhang
- College of Environmental Science and Engineering, Yangzhou University, China.
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2
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Yang J, Sun Y, Wang Y, Hao W, Cheng K. Structural and DNA end resection study of the bacterial NurA-HerA complex. BMC Biol 2023; 21:42. [PMID: 36829173 PMCID: PMC9960219 DOI: 10.1186/s12915-023-01542-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
BACKGROUND The nuclease NurA and the ATPase/translocase HerA play a vital role in repair of double-strand breaks (DSB) during the homologous recombination in archaea. A NurA-HerA complex is known to mediate DSB DNA end resection, leading to formation of a free 3' end used to search for the homologous sequence. Despite the structures of individual archaeal types of NurA and HerA having been reported, there is limited information regarding the molecular mechanisms underlying this process. Some bacteria also possess homologs of NurA and HerA; however, the bacterial type of this complex, as well as the detailed mechanisms underlying the joining of NurA-HerA in DSB DNA end resection, remains unclear. RESULTS We report for the first time the crystal structures of Deinococcus radiodurans HerA (drHerA) in the nucleotide-free and ADP-binding modes. A D. radiodurans NurA-HerA complex structure was constructed according to a low-resolution cryo-electron microscopy map. We performed site-directed mutagenesis to map the drNurA-HerA interaction sites, suggesting that their interaction is mainly mediated by ionic links, in contrast to previously characterized archaeal NurA-HerA interactions. The key residues responsible for the DNA translocation activity, DNA unwinding activity, and catalytic activities of the drNurA-HerA complex were identified. A HerA/FtsK-specific translocation-related motif (TR motif) that guarantees the processivity of double-stranded DNA (dsDNA) translocation was identified. Moreover, a mechanism for the translocation-regulated resection of the 5' tail of broken dsDNA and the corresponding generation of a recombinogenic 3' single-stranded DNA tail by the drNurA-HerA complex was elucidated. CONCLUSIONS Our work provides new insights into the mechanism underlying bacterial NurA-HerA-mediated DSB DNA end resection, and the way this complex digests the 5' tail of a DNA duplex and provides long 3' free end for strand invasion in the bacterial homologous recombination process.
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Affiliation(s)
- Jieyu Yang
- grid.410595.c0000 0001 2230 9154Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, 311121 China
| | - Yiyang Sun
- grid.410595.c0000 0001 2230 9154Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, 311121 China
| | - Ying Wang
- grid.410595.c0000 0001 2230 9154Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, 311121 China
| | - Wanshan Hao
- grid.410595.c0000 0001 2230 9154Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, 311121 China
| | - Kaiying Cheng
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, 311121, China. .,State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China.
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3
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Beltran LC, Cvirkaite-Krupovic V, Miller J, Wang F, Kreutzberger MAB, Patkowski JB, Costa TRD, Schouten S, Levental I, Conticello VP, Egelman EH, Krupovic M. Archaeal DNA-import apparatus is homologous to bacterial conjugation machinery. Nat Commun 2023; 14:666. [PMID: 36750723 PMCID: PMC9905601 DOI: 10.1038/s41467-023-36349-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/27/2023] [Indexed: 02/09/2023] Open
Abstract
Conjugation is a major mechanism of horizontal gene transfer promoting the spread of antibiotic resistance among human pathogens. It involves establishing a junction between a donor and a recipient cell via an extracellular appendage known as the mating pilus. In bacteria, the conjugation machinery is encoded by plasmids or transposons and typically mediates the transfer of cognate mobile genetic elements. Much less is known about conjugation in archaea. Here, we determine atomic structures by cryo-electron microscopy of three conjugative pili, two from hyperthermophilic archaea (Aeropyrum pernix and Pyrobaculum calidifontis) and one encoded by the Ti plasmid of the bacterium Agrobacterium tumefaciens, and show that the archaeal pili are homologous to bacterial mating pili. However, the archaeal conjugation machinery, known as Ced, has been 'domesticated', that is, the genes for the conjugation machinery are encoded on the chromosome rather than on mobile genetic elements, and mediates the transfer of cellular DNA.
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Affiliation(s)
- Leticia C Beltran
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22903, USA
| | | | - Jessalyn Miller
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
| | - Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22903, USA
- Department of Biochemistry and Molecular Genetics, University of Alabama Birmingham, Birmingham, AL, 35233, USA
| | - Mark A B Kreutzberger
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22903, USA
| | - Jonasz B Patkowski
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Tiago R D Costa
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Stefan Schouten
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Texel, The Netherlands
| | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, 22903, USA
| | | | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22903, USA.
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, 75015, Paris, France.
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4
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Xu Y, Xu L, Qin C, Wang L, Guo J, Hua Y, Zhao Y. Mechanisms of helicase activated DNA end resection in bacteria. Structure 2022; 30:1298-1306.e3. [PMID: 35841886 DOI: 10.1016/j.str.2022.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/26/2022] [Accepted: 06/21/2022] [Indexed: 12/01/2022]
Abstract
DNA end resection mediated by the coordinated action of nuclease and helicase is a crucial step in initiating homologous recombination. The end-resection apparatus NurA nuclease and HerA helicase are present in both archaea and bacteria. Here, we report the cryo-electron microscopy structure of a bacterial HerA-NurA complex from Deinococcus radiodurans. The structure reveals a barrel-like hexameric HerA and a distinctive NurA dimer subcomplex, which has a unique extended N-terminal region (ENR) involved in bacterial NurA dimerization and activation. In addition to the long protruding linking loop and the C-terminal α helix of NurA, the flexible ENR is close to the HerA-NurA interface and divides the central channel of the DrNurA dimer into two halves, suggesting a possible mechanism of DNA end processing. In summary, this work provides new insights into the structure, assembly, and activation mechanisms of bacterial DNA end resection mediated by a minimal end-resection apparatus.
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Affiliation(s)
- Ying Xu
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Lingyi Xu
- Department of Biophysics, Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Chen Qin
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Liangyan Wang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Jiangtao Guo
- Department of Biophysics, Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China.
| | - Yuejin Hua
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou, China; Cancer Center, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| | - Ye Zhao
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou, China; Cancer Center, Zhejiang University, Hangzhou, Zhejiang 310058, China.
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5
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De Falco M, Porritiello A, Rota F, Scognamiglio V, Antonacci A, del Monaco G, De Felice M. The Finely Coordinated Action of SSB and NurA/HerA Complex Strictly Regulates the DNA End Resection Process in Saccharolobus solfataricus. Int J Mol Sci 2022; 23:ijms23052582. [PMID: 35269725 PMCID: PMC8910471 DOI: 10.3390/ijms23052582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/22/2022] [Accepted: 02/23/2022] [Indexed: 11/16/2022] Open
Abstract
Generation of the 3' overhang is a critical step during homologous recombination (HR) and replication fork rescue processes. This event is usually performed by a series of DNA nucleases and/or helicases. The nuclease NurA and the ATPase HerA, together with the highly conserved MRE11/RAD50 proteins, play an important role in generating 3' single-stranded DNA during archaeal HR. Little is known, however, about HerA-NurA function and activation of this fundamental and complicated DNA repair process. Herein, we analyze the functional relationship among NurA, HerA and the single-strand binding protein SSB from Saccharolubus solfataricus. We demonstrate that SSB clearly inhibits NurA endonuclease activity and its exonuclease activities also when in combination with HerA. Moreover, we show that SSB binding to DNA is greatly stimulated by the presence of either NurA or NurA/HerA. In addition, if on the one hand NurA binding is not influenced, on the other hand, HerA binding is reduced when SSB is present in the reaction. In accordance with what has been observed, we have shown that HerA helicase activity is not stimulated by SSB. These data suggest that, in archaea, the DNA end resection process is governed by the strictly combined action of NurA, HerA and SSB.
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Affiliation(s)
- Mariarosaria De Falco
- Institute of Biosciences and BioResources, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy; (A.P.); (F.R.); (G.d.M.)
- Correspondence: (M.D.F.); (M.D.F.)
| | - Alessandra Porritiello
- Institute of Biosciences and BioResources, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy; (A.P.); (F.R.); (G.d.M.)
| | - Federica Rota
- Institute of Biosciences and BioResources, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy; (A.P.); (F.R.); (G.d.M.)
| | - Viviana Scognamiglio
- Department of Chemical Sciences and Materials Technologies, Institute of Crystallography, National Research Council, Via Salaria Km 29,300, Monterotondo, 00015 Rome, Italy; (V.S.); (A.A.)
| | - Amina Antonacci
- Department of Chemical Sciences and Materials Technologies, Institute of Crystallography, National Research Council, Via Salaria Km 29,300, Monterotondo, 00015 Rome, Italy; (V.S.); (A.A.)
| | - Giovanni del Monaco
- Institute of Biosciences and BioResources, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy; (A.P.); (F.R.); (G.d.M.)
| | - Mariarita De Felice
- Institute of Biosciences and BioResources, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy; (A.P.); (F.R.); (G.d.M.)
- Correspondence: (M.D.F.); (M.D.F.)
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6
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Genetic and Biochemical Characterizations of aLhr1 Helicase in the Thermophilic Crenarchaeon Sulfolobus acidocaldarius. Catalysts 2021. [DOI: 10.3390/catal12010034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Homologous recombination (HR) refers to the process of information exchange between homologous DNA duplexes and is composed of four main steps: end resection, strand invasion and formation of a Holliday junction (HJ), branch migration, and resolution of the HJ. Within each step of HR in Archaea, the helicase-promoting branch migration is not fully understood. Previous biochemical studies identified three candidates for archaeal helicase promoting branch migration in vitro: Hjm/Hel308, PINA, and archaeal long helicase related (aLhr) 2. However, there is no direct evidence of their involvement in HR in vivo. Here, we identified a novel helicase encoded by Saci_0814, isolated from the thermophilic crenarchaeon Sulfolobus acidocaldarius; the helicase dissociated a synthetic HJ. Notably, HR frequency in the Saci_0814-deleted strain was lower than that of the parent strain (5-fold decrease), indicating that Saci_0814 may be involved in HR in vivo. Saci_0814 is classified as an aLhr1 under superfamily 2 helicases; its homologs are conserved among Archaea. Purified protein produced in Escherichia coli showed branch migration activity in vitro. Based on both genetic and biochemical evidence, we suggest that aLhr1 is involved in HR and may function as a branch migration helicase in S. acidocaldarius.
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7
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De Falco M, De Felice M. Take a Break to Repair: A Dip in the World of Double-Strand Break Repair Mechanisms Pointing the Gaze on Archaea. Int J Mol Sci 2021; 22:ijms222413296. [PMID: 34948099 PMCID: PMC8708640 DOI: 10.3390/ijms222413296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/24/2022] Open
Abstract
All organisms have evolved many DNA repair pathways to counteract the different types of DNA damages. The detection of DNA damage leads to distinct cellular responses that bring about cell cycle arrest and the induction of DNA repair mechanisms. In particular, DNA double-strand breaks (DSBs) are extremely toxic for cell survival, that is why cells use specific mechanisms of DNA repair in order to maintain genome stability. The choice among the repair pathways is mainly linked to the cell cycle phases. Indeed, if it occurs in an inappropriate cellular context, it may cause genome rearrangements, giving rise to many types of human diseases, from developmental disorders to cancer. Here, we analyze the most recent remarks about the main pathways of DSB repair with the focus on homologous recombination. A thorough knowledge in DNA repair mechanisms is pivotal for identifying the most accurate treatments in human diseases.
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8
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Marshall CJ, Santangelo TJ. Archaeal DNA Repair Mechanisms. Biomolecules 2020; 10:E1472. [PMID: 33113933 PMCID: PMC7690668 DOI: 10.3390/biom10111472] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/29/2022] Open
Abstract
Archaea often thrive in environmental extremes, enduring levels of heat, pressure, salinity, pH, and radiation that prove intolerable to most life. Many environmental extremes raise the propensity for DNA damaging events and thus, impact DNA stability, placing greater reliance on molecular mechanisms that recognize DNA damage and initiate accurate repair. Archaea can presumably prosper in harsh and DNA-damaging environments in part due to robust DNA repair pathways but surprisingly, no DNA repair pathways unique to Archaea have been described. Here, we review the most recent advances in our understanding of archaeal DNA repair. We summarize DNA damage types and their consequences, their recognition by host enzymes, and how the collective activities of many DNA repair pathways maintain archaeal genomic integrity.
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Affiliation(s)
| | - Thomas J. Santangelo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA;
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9
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Bacterial non-specific nucleases of the phospholipase D superfamily and their biotechnological potential. Appl Microbiol Biotechnol 2020; 104:3293-3304. [PMID: 32086594 DOI: 10.1007/s00253-020-10459-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 12/19/2022]
Abstract
Bacterial non-specific nucleases are ubiquitously distributed and involved in numerous intra- and extracellular processes. Although all nucleases share the basic chemistry for the hydrolysis of phosphodiester bonds in nucleic acid molecules, the catalysis comprises diverse modes of action, which offers great potential for versatile biotechnological applications. A major criterium for their differentiation is substrate specificity. Specific endonucleases are widely used as restriction enzymes in molecular biology approaches, whereas the main applications of non-specific nucleases (NSNs) are the removal of nucleic acids from crude extracts in industrial downstream processing and the prevention of cell clumping in microfabricated channels. In nature, the predominant role of NSNs is the acquisition of nutrient sources such as nucleotides and phosphates. The number of extensively characterized NSNs and available structures is limited. Moreover, their applicability is mostly challenged by the presence of metal chelators that impede the hydrolysis of nucleic acids in a metal ion-dependent manner. However, a few metal ion-independent NSNs that tolerate the presence of metal chelators have been characterized in recent years with none being commercially available to date. The classification and biotechnological potential of bacterial NSNs with a special focus on metal ion-independent nucleases are presented and discussed.Key Points • Bacterial phospholipases (PLD-family) exhibit nucleolytic activity. • Bacterial nucleases of the PLD-family are metal ion-independent. • NSNs can be used in downstream processing approaches.
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10
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White MF, Allers T. DNA repair in the archaea-an emerging picture. FEMS Microbiol Rev 2018; 42:514-526. [PMID: 29741625 DOI: 10.1093/femsre/fuy020] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/02/2018] [Indexed: 12/12/2022] Open
Abstract
There has long been a fascination in the DNA repair pathways of archaea, for two main reasons. Firstly, many archaea inhabit extreme environments where the rate of physical damage to DNA is accelerated. These archaea might reasonably be expected to have particularly robust or novel DNA repair pathways to cope with this. Secondly, the archaea have long been understood to be a lineage distinct from the bacteria, and to share a close relationship with the eukarya, particularly in their information processing systems. Recent discoveries suggest the eukarya arose from within the archaeal domain, and in particular from lineages related to the TACK superphylum and Lokiarchaea. Thus, archaeal DNA repair proteins and pathways can represent a useful model system. This review focuses on recent advances in our understanding of archaeal DNA repair processes including base excision repair, nucleotide excision repair, mismatch repair and double-strand break repair. These advances are discussed in the context of the emerging picture of the evolution and relationship of the three domains of life.
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Affiliation(s)
- Malcolm F White
- Biomedical Sciences Research Complex, School of Biology, University of St Andrews, Fife KY16 9ST, UK
| | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
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11
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Resistance to UV Irradiation Caused by Inactivation of nurA and herA Genes in Thermus thermophilus. J Bacteriol 2018; 200:JB.00201-18. [PMID: 29844033 DOI: 10.1128/jb.00201-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/23/2018] [Indexed: 11/20/2022] Open
Abstract
NurA and HerA are thought to be essential proteins for DNA end resection in archaeal homologous recombination systems. Thermus thermophilus, an extremely thermophilic eubacterium, has proteins that exhibit significant sequence similarity to archaeal NurA and HerA. To unveil the cellular function of NurA and HerA in T. thermophilus, we performed phenotypic analysis of disruptant mutants of nurA and herA with or without DNA-damaging agents. The nurA and herA genes were not essential for survival, and their deletion had no effect on cell growth and genome integrity. Unexpectedly, these disruptants of T. thermophilus showed increased resistance to UV irradiation and mitomycin C treatment. Further, these disruptants and the wild type displayed no difference in sensitivity to oxidative stress and a DNA replication inhibitor. T. thermophilus NurA had nuclease activity, and HerA had ATPase. The overexpression of loss-of-function mutants of nurA and herA in the respective disruptants showed no complementation, suggesting their enzymatic activities were involved in the UV sensitivity. In addition, T. thermophilus NurA and HerA interacted with each other in vitro and in vivo, forming a complex with 2:6 stoichiometry. These results suggest that the NurA-HerA complex has an architecture similar to that of archaeal counterparts but that it impairs, rather than promotes, the repair of photoproducts and DNA cross-links in T. thermophilus cells. This cellular function is distinctly different from that of archaeal NurA and HerA.IMPORTANCE Many nucleases and helicases are engaged in homologous recombination-mediated DNA repair. Previous in vitro analyses in archaea indicated that NurA and HerA are the recombination-related nuclease and helicase. However, their cellular function had not been fully understood, especially in bacterial cells. In this study, we performed in vivo analyses to address the cellular function of nurA and herA in an extremely thermophilic bacterium, Thermus thermophilus As a result, T. thermophilus NurA and HerA exhibited an interfering effect on the repair of several instances of DNA damage in the cell, which is in contrast to the results in archaea. This finding will facilitate our understanding of the diverse cellular functions of the recombination-related nucleases and helicases.
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12
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De Falco M, Massa F, Rossi M, De Felice M. The Sulfolobus solfataricus RecQ-like DNA helicase Hel112 inhibits the NurA/HerA complex exonuclease activity. Extremophiles 2018; 22:581-589. [PMID: 29488113 DOI: 10.1007/s00792-018-1018-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/21/2018] [Indexed: 02/03/2023]
Abstract
ATPase/Helicases and nucleases play important roles in DNA end-resection, a critical step during homologous recombination repair in all organisms. In hyperthermophilic archaea the exo-endonuclease NurA and the ATPase HerA cooperate with the highly conserved Mre11-Rad50 complex in 3' single-stranded DNA (ssDNA) end processing to coordinate repair of double-stranded DNA breaks. Little is known, however, about the assembly mechanism and activation of the HerA-NurA complex. In this study we demonstrate that the NurA exonuclease activity is inhibited by the Sulfolobus solfataricus RecQ-like Hel112 helicase. Inhibition occurs both in the presence and in the absence of HerA, but is much stronger when NurA is in complex with HerA. In contrast, the endonuclease activity of NurA is not affected by the presence of Hel112. Taken together these results suggest that the functional interaction between NurA/HerA and Hel112 is important for DNA end-resection in archaeal homologous recombination.
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Affiliation(s)
- Mariarosaria De Falco
- Institute of Biosciences and Bioresources, Consiglio Nazionale delle Ricerche, 80131, Naples, Italy.
| | - Federica Massa
- Institute of Biosciences and Bioresources, Consiglio Nazionale delle Ricerche, 80131, Naples, Italy
| | - Mosè Rossi
- Institute of Biosciences and Bioresources, Consiglio Nazionale delle Ricerche, 80131, Naples, Italy
| | - Mariarita De Felice
- Institute of Biosciences and Bioresources, Consiglio Nazionale delle Ricerche, 80131, Naples, Italy.
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