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Xu J, Wu C, Yang Z, Liu W, Chen H, Batool K, Yao J, Fan X, Wu J, Rao W, Huang T, Xu L, Guan X, Zhang L. For: Pesticide biochemistry and physiology recG is involved with the resistance of Bt to UV. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 167:104599. [PMID: 32527443 DOI: 10.1016/j.pestbp.2020.104599] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 03/07/2020] [Accepted: 05/06/2020] [Indexed: 06/11/2023]
Abstract
As an ATP-dependent DNA helicase, RecG can repair DNA replication forks in many organisms. However, knowledge of recG in Bacillus thuringiensis (Bt) is limited. In our previous study, recG was found damaged in Bt LLP29-M19, which was more resistant to ultraviolet light (UV) after exposing Bt LLP29 to UV for 19 generations. To further understand the function of recG in the mechanism of Bt UV resistance, recG was knocked out and recovered with homologous recombination technology in Bt LLP29. Comparing the resistance of the different mutants to UVB, Bt ∆recG-LLP29 lacking recG was found more sensitive to UVB, hydroxyurea (HU) and H2O2 than LLP29 and the complementation strain. To compare the expression level of recG in the Bt strains under different UV treatments, Quantitative Real-time PCR (RT-qPCR) of recG was performed in the tested Bt strains, which showed that the expression level of recG in Bt ∆recG-LLP29 was substantially lower than that in the original strain and complementation strain. Interestingly, when exposed to UV for 20 min, RecG expression in both Bt LLP29 and Bt recG-R was the highest. The unwinding activity of recG in Bt LLP29 and the complementation strain were also found higher than that of the recG knockout strain, Bt ∆recG-LLP29. These results demonstrate that recG is involved with the resistance of Bt to UV. These findings not only enhance the understanding of the Bt UV resistance mechanism, but also provide an important theoretical basis for the application of Bt.
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Affiliation(s)
- Jin Xu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Chenxu Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Zhaohui Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Wencheng Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Hong Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Khadija Batool
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Junmin Yao
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xiao Fan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Juan Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Wenhua Rao
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Tianpei Huang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Lei Xu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Lingling Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
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2
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Singh A, Vijayan M, Nagaraju G. RecG wed : A probable novel regulator in the resolution of branched DNA structures in mycobacteria. IUBMB Life 2018; 70:786-794. [PMID: 30240108 DOI: 10.1002/iub.1881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/02/2018] [Accepted: 05/04/2018] [Indexed: 01/31/2023]
Abstract
Structure-specific helicases, such as RecG, play an important role in the resolution of recombination intermediates. A bioinformatic analysis of mycobacterial genomes led to the identification of a protein (RecGwed ) with a C-terminal "edge" domain, similar to the wedge domain of RecG. RecGwed is predominately found in the phylum Actinobacteria and in few human pathogens. Mycobacterium smegmatis RecGwed was able to bind branched DNA structures in vitro but failed to interact with single- or double-stranded DNA. The expression of recGwed in M. smegmatis cells was up-regulated during stationary phase/UV damage and down-regulated during MMS/H2 O2 treatment. These observations indicate the possible involvement of RecGwed in transactions during recombination events, that proceed though branched DNA intermediates. © 2018 IUBMB Life, 70(8):786-794, 2018.
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Affiliation(s)
- Amandeep Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - M Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Ganesh Nagaraju
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
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3
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Frye SA, Beyene GT, Namouchi A, Gómez-Muñoz M, Homberset H, Kalayou S, Riaz T, Tønjum T, Balasingham SV. The helicase DinG responds to stress due to DNA double strand breaks. PLoS One 2017; 12:e0187900. [PMID: 29121674 PMCID: PMC5679670 DOI: 10.1371/journal.pone.0187900] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 10/27/2017] [Indexed: 12/20/2022] Open
Abstract
Neisseria meningitidis (Nm) is a Gram-negative nasopharyngeal commensal that can cause septicaemia and meningitis. The neisserial DNA damage-inducible protein DinG is a helicase related to the mammalian helicases XPD and FANCJ. These helicases belong to superfamily 2, are ATP dependent and exert 5′ → 3′ directionality. To better understand the role of DinG in neisserial genome maintenance, the Nm DinG (DinGNm) enzymatic activities were assessed in vitro and phenotypical characterization of a dinG null mutant (NmΔdinG) was performed. Like its homologues, DinGNm possesses 5′ → 3′ directionality and prefers DNA substrates containing a 5′-overhang. ATPase activity of DinGNm is strictly DNA-dependent and DNA unwinding activity requires nucleoside triphosphate and divalent metal cations. DinGNm directly binds SSBNm with a Kd of 313 nM. Genotoxic stress analysis demonstrated that NmΔdinG was more sensitive to double-strand DNA breaks (DSB) induced by mitomycin C (MMC) than the Nm wildtype, defining the role of neisserial DinG in DSB repair. Notably, when NmΔdinG cells grown under MMC stress assessed by quantitative mass spectrometry, 134 proteins were shown to be differentially abundant (DA) compared to unstressed NmΔdinG cells. Among the DNA replication, repair and recombination proteins affected, polymerase III subunits and recombinational repair proteins RuvA, RuvB, RecB and RecD were significantly down regulated while TopA and SSB were upregulated under stress condition. Most of the other DA proteins detected are involved in metabolic functions. The present study shows that the helicase DinG is probably involved in regulating metabolic pathways as well as in genome maintenance.
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Affiliation(s)
- Stephan A. Frye
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
- * E-mail: (SVB); (SAF)
| | | | - Amine Namouchi
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | | | | | - Shewit Kalayou
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Tahira Riaz
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Tone Tønjum
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
- Department of Microbiology, University of Oslo, Oslo, Norway
| | - Seetha V. Balasingham
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
- * E-mail: (SVB); (SAF)
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Hovland E, Beyene GT, Frye SA, Homberset H, Balasingham SV, Gómez-Muñoz M, Derrick JP, Tønjum T, Ambur OH. DprA from Neisseria meningitidis: properties and role in natural competence for transformation. MICROBIOLOGY-SGM 2017; 163:1016-1029. [PMID: 28696187 PMCID: PMC5817196 DOI: 10.1099/mic.0.000489] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
DNA processing chain A (DprA) is a DNA-binding protein that is ubiquitous in bacteria and expressed in some archaea. DprA is active in many bacterial species that are competent for transformation of DNA, but its role in Neisseriameningitidis (Nm) is not well characterized. An Nm mutant lacking DprA was constructed, and the phenotypes of the wild-type and ΔdprA mutant were compared. The salient feature of the phenotype of dprA null cells is the total lack of competence for genetic transformation shown by all of the donor DNA substrates tested in this study. Here, Nm wild-type and dprA null cells appeared to be equally resistant to genotoxic stress. The gene encoding DprANm was cloned and overexpressed, and the biological activities of DprANm were further investigated. DprANm binds ssDNA more strongly than dsDNA, but lacks DNA uptake sequence-specific DNA binding. DprANm dimerization and interaction with the C-terminal part of the single-stranded binding protein SSBNmwere demonstrated. dprA is co-expressed with smg, a downstream gene of unknown function, and the gene encoding topoisomerase 1, topA.
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Affiliation(s)
- Eirik Hovland
- Department of Microbiology, University of Oslo, Oslo, Norway.,Present address: Lovisenberg Diaconal Hospital, Oslo, Norway
| | | | - Stephan A Frye
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | | | | | | | - Jeremy P Derrick
- Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Oxford Road, Manchester, UK
| | - Tone Tønjum
- Department of Microbiology, Oslo University Hospital, Oslo, Norway.,Department of Microbiology, University of Oslo, Oslo, Norway
| | - Ole H Ambur
- Department of Microbiology, Oslo University Hospital, Oslo, Norway.,Present address: Department of Life Sciences and Health, Oslo and Akershus University College of Applied Sciences, Norway
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5
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Plekhanova E, Vishnyakova MA, Bulyntsev S, Chang PL, Carrasquilla-Garcia N, Negash K, Wettberg EV, Noujdina N, Cook DR, Samsonova MG, Nuzhdin SV. Genomic and phenotypic analysis of Vavilov's historic landraces reveals the impact of environment and genomic islands of agronomic traits. Sci Rep 2017; 7:4816. [PMID: 28684880 PMCID: PMC5500531 DOI: 10.1038/s41598-017-05087-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 05/24/2017] [Indexed: 12/30/2022] Open
Abstract
The Vavilov Institute of Plant Genetic Resources (VIR), in St. Petersburg, Russia, houses a unique genebank, with historical collections of landraces. When they were collected, the geographical distribution and genetic diversity of most crops closely reflected their historical patterns of cultivation established over the preceding millennia. We employed a combination of genomics, computational biology and phenotyping to characterize VIR's 147 chickpea accessions from Turkey and Ethiopia, representing chickpea's center of origin and a major location of secondary diversity. Genotyping by sequencing identified 14,059 segregating polymorphisms and genome-wide association studies revealed 28 GWAS hits in potential candidate genes likely to affect traits of agricultural importance. The proportion of polymorphisms shared among accessions is a strong predictor of phenotypic resemblance, and of environmental similarity between historical sampling sites. We found that 20 out of 28 polymorphisms, associated with multiple traits, including days to maturity, plant phenology, and yield-related traits such as pod number, localized to chromosome 4. We hypothesize that selection and introgression via inadvertent hybridization between more and less advanced morphotypes might have resulted in agricultural improvement genes being aggregated to genomic 'agro islands', and in genotype-to-phenotype relationships resembling widespread pleiotropy.
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Affiliation(s)
- Elena Plekhanova
- Department of Applied Mathematics, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, Russia
| | - Margarita A Vishnyakova
- Federal Research Centre All-Russian N.I. Vavilov Institute of Plant Genetic Resources (VIR), St. Petersburg, Russia
| | - Sergey Bulyntsev
- Federal Research Centre All-Russian N.I. Vavilov Institute of Plant Genetic Resources (VIR), St. Petersburg, Russia
| | - Peter L Chang
- Department of Plant Pathology, University of California, Davis, CA, USA.,Program Molecular and Computation Biology, Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA, USA
| | | | - Kassaye Negash
- Department of Plant Pathology, University of California, Davis, CA, USA
| | - Eric von Wettberg
- Department of Biological Sciences and International Center for Tropical Botany, Florida International University, Miami, FL, USA
| | - Nina Noujdina
- School of Architecture, University of Southern California, Los Angeles, CA, USA
| | - Douglas R Cook
- Department of Plant Pathology, University of California, Davis, CA, USA
| | - Maria G Samsonova
- Department of Applied Mathematics, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, Russia
| | - Sergey V Nuzhdin
- Department of Applied Mathematics, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, Russia. .,Program Molecular and Computation Biology, Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA, USA.
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6
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Azeroglu B, Leach DRF. RecG controls DNA amplification at double-strand breaks and arrested replication forks. FEBS Lett 2017; 591:1101-1113. [PMID: 28155219 PMCID: PMC5412681 DOI: 10.1002/1873-3468.12583] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/13/2017] [Accepted: 01/28/2017] [Indexed: 12/16/2022]
Abstract
DNA amplification is a powerful mutational mechanism that is a hallmark of cancer and drug resistance. It is therefore important to understand the fundamental pathways that cells employ to avoid over‐replicating sections of their genomes. Recent studies demonstrate that, in the absence of RecG, DNA amplification is observed at sites of DNA double‐strand break repair (DSBR) and of DNA replication arrest that are processed to generate double‐strand ends. RecG also plays a role in stabilising joint molecules formed during DSBR. We propose that RecG prevents a previously unrecognised mechanism of DNA amplification that we call reverse‐restart, which generates DNA double‐strand ends from incorrect loading of the replicative helicase at D‐loops formed by recombination, and at arrested replication forks.
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Affiliation(s)
- Benura Azeroglu
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, UK
| | - David R F Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, UK
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7
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Beyene GT, Balasingham SV, Frye SA, Namouchi A, Homberset H, Kalayou S, Riaz T, Tønjum T. Characterization of the Neisseria meningitidis Helicase RecG. PLoS One 2016; 11:e0164588. [PMID: 27736945 PMCID: PMC5063381 DOI: 10.1371/journal.pone.0164588] [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: 06/26/2016] [Accepted: 09/27/2016] [Indexed: 11/19/2022] Open
Abstract
Neisseria meningitidis (Nm) is a Gram-negative oral commensal that opportunistically can cause septicaemia and/or meningitis. Here, we overexpressed, purified and characterized the Nm DNA repair/recombination helicase RecG (RecGNm) and examined its role during genotoxic stress. RecGNm possessed ATP-dependent DNA binding and unwinding activities in vitro on a variety of DNA model substrates including a Holliday junction (HJ). Database searching of the Nm genomes identified 49 single nucleotide polymorphisms (SNPs) in the recGNm including 37 non-synonymous SNPs (nsSNPs), and 7 of the nsSNPs were located in the codons for conserved active site residues of RecGNm. A transient reduction in transformation of DNA was observed in the Nm ΔrecG strain as compared to the wildtype. The gene encoding recGNm also contained an unusually high number of the DNA uptake sequence (DUS) that facilitate transformation in neisserial species. The differentially abundant protein profiles of the Nm wildtype and ΔrecG strains suggest that expression of RecGNm might be linked to expression of other proteins involved in DNA repair, recombination and replication, pilus biogenesis, glycan biosynthesis and ribosomal activity. This might explain the growth defect that was observed in the Nm ΔrecG null mutant.
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Affiliation(s)
| | | | - Stephan A. Frye
- Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway
| | - Amine Namouchi
- Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway
| | | | - Shewit Kalayou
- Department of Microbiology, University of Oslo, Oslo, Norway
| | - Tahira Riaz
- Department of Microbiology, University of Oslo, Oslo, Norway
| | - Tone Tønjum
- Department of Microbiology, University of Oslo, Oslo, Norway
- Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway
- * E-mail:
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8
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Lloyd RG, Rudolph CJ. 25 years on and no end in sight: a perspective on the role of RecG protein. Curr Genet 2016; 62:827-840. [PMID: 27038615 PMCID: PMC5055574 DOI: 10.1007/s00294-016-0589-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/02/2016] [Indexed: 11/27/2022]
Abstract
The RecG protein of Escherichia coli is a double-stranded DNA translocase that unwinds a variety of branched substrates in vitro. Although initially associated with homologous recombination and DNA repair, studies of cells lacking RecG over the past 25 years have led to the suggestion that the protein might be multi-functional and associated with a number of additional cellular processes, including initiation of origin-independent DNA replication, the rescue of stalled or damaged replication forks, replication restart, stationary phase or stress-induced 'adaptive' mutations and most recently, naïve adaptation in CRISPR-Cas immunity. Here we discuss the possibility that many of the phenotypes of recG mutant cells that have led to this conclusion may stem from a single defect, namely the failure to prevent re-replication of the chromosome. We also present data indicating that this failure does indeed contribute substantially to the much-reduced recovery of recombinants in conjugational crosses with strains lacking both RecG and the RuvABC Holliday junction resolvase.
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Affiliation(s)
- Robert G Lloyd
- Centre for Genetics and Genomics, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK
| | - Christian J Rudolph
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.
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9
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Mycobacterium smegmatis HelY Is an RNA-Activated ATPase/dATPase and 3'-to-5' Helicase That Unwinds 3'-Tailed RNA Duplexes and RNA:DNA Hybrids. J Bacteriol 2015; 197:3057-65. [PMID: 26170411 DOI: 10.1128/jb.00418-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/07/2015] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Mycobacteria have a large and distinctive ensemble of DNA helicases that function in DNA replication, repair, and recombination. Little is known about the roster of RNA helicases in mycobacteria or their roles in RNA transactions. The 912-amino-acid Mycobacterium smegmatis HelY (MSMEG_3885) protein is a bacterial homolog of the Mtr4 and Ski2 helicases that regulate RNA 3' processing and turnover by the eukaryal exosome. Here we characterize HelY as an RNA-stimulated ATPase/dATPase and an ATP/dATP-dependent 3'-to-5' helicase. HelY requires a 3' single-strand RNA tail (a loading RNA strand) to displace the complementary strand of a tailed RNA:RNA or RNA:DNA duplex. The findings that HelY ATPase is unresponsive to a DNA polynucleotide cofactor and that HelY is unable to unwind a 3'-tailed duplex in which the loading strand is DNA distinguish HelY from other mycobacterial nucleoside triphosphatases/helicases characterized previously. The biochemical properties of HelY, which resemble those of Mtr4/Ski2, hint at a role for HelY in mycobacterial RNA catabolism. IMPORTANCE RNA helicases play crucial roles in transcription, RNA processing, and translation by virtue of their ability to alter RNA secondary structure or remodel RNA-protein interactions. In eukarya, the RNA helicases Mtr4 and Ski2 regulate RNA 3' resection by the exosome. Mycobacterium smegmatis HelY, a bacterial homolog of Mtr4/Ski2, is characterized here as a unidirectional helicase, powered by RNA-dependent ATP/dATP hydrolysis, that tracks 3' to 5' along a loading RNA strand to displace the complementary strand of a tailed RNA:RNA or RNA:DNA duplex. The biochemical properties of HelY suggest a role in bacterial RNA transactions. HelY homologs are present in pathogenic mycobacteria (e.g., M. tuberculosis and M. leprae) and are widely prevalent in Actinobacteria and Cyanobacteria but occur sporadically elsewhere in the bacterial domain.
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10
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Cañas C, Suzuki Y, Marchisone C, Carrasco B, Freire-Benéitez V, Takeyasu K, Alonso JC, Ayora S. Interaction of branch migration translocases with the Holliday junction-resolving enzyme and their implications in Holliday junction resolution. J Biol Chem 2014; 289:17634-46. [PMID: 24770420 DOI: 10.1074/jbc.m114.552794] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Double-strand break repair involves the formation of Holliday junction (HJ) structures that need to be resolved to promote correct replication and chromosomal segregation. The molecular mechanisms of HJ branch migration and/or resolution are poorly characterized in Firmicutes. Genetic evidence suggested that the absence of the RuvAB branch migration translocase and the RecU HJ resolvase is synthetically lethal in Bacillus subtilis, whereas a recU recG mutant was viable. In vitro RecU, which is restricted to bacteria of the Firmicutes phylum, binds HJs with high affinity. In this work we found that RecU does not bind simultaneously with RecG to a HJ. RuvB by interacting with RecU bound to the central region of HJ DNA, loses its nonspecific association with DNA, and re-localizes with RecU to form a ternary complex. RecU cannot stimulate the ATPase or branch migration activity of RuvB. The presence of RuvB·ATPγS greatly stimulates RecU-mediated HJ resolution, but the addition of ATP or RuvA abolishes this stimulatory effect. A RecU·HJ·RuvAB complex might be formed. RecU does not increase the RuvAB activities but slightly inhibits them.
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Affiliation(s)
- Cristina Cañas
- From the Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Biotecnología Microbiana, 28049 Madrid, Spain and
| | - Yuki Suzuki
- Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Chiara Marchisone
- From the Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Biotecnología Microbiana, 28049 Madrid, Spain and
| | - Begoña Carrasco
- From the Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Biotecnología Microbiana, 28049 Madrid, Spain and
| | - Verónica Freire-Benéitez
- From the Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Biotecnología Microbiana, 28049 Madrid, Spain and
| | - Kunio Takeyasu
- Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Juan C Alonso
- From the Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Biotecnología Microbiana, 28049 Madrid, Spain and
| | - Silvia Ayora
- From the Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Biotecnología Microbiana, 28049 Madrid, Spain and
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11
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Zegeye ED, Balasingham SV, Laerdahl JK, Homberset H, Kristiansen PE, Tønjum T. Effects of conserved residues and naturally occurring mutations on Mycobacterium tuberculosis RecG helicase activity. MICROBIOLOGY-SGM 2013; 160:217-227. [PMID: 24169816 DOI: 10.1099/mic.0.072140-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
RecG is a helicase that is conserved in nearly all bacterial species. The prototypical Escherichia coli RecG promotes regression of stalled replication forks, participates in DNA recombination and DNA repair, and prevents aberrant replication. Mycobacterium tuberculosis RecG (RecGMtb) is a DNA-dependent ATPase that unwinds a variety of DNA substrates, although its preferred substrate is a Holliday junction. Here, we performed site-directed mutagenesis of selected residues in the wedge domain and motifs Q, I, Ib and VI of RecGMtb. Three of the 10 substitution mutations engineered were detected previously as naturally occurring SNPs in the gene encoding RecGMtb. Alanine substitution mutations at residues Q292, F286, K321 and R627 abolished the RecGMtb unwinding activity, whilst RecGMtb F99A, P285S and T408A mutants exhibited ~25-50 % lower unwinding activity than WT. We also found that RecGMtb bound ATP in the absence of a DNA cofactor.
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Affiliation(s)
- Ephrem Debebe Zegeye
- Centre for Molecular Biology and Neuroscience and Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway.,Centre for Molecular Biology and Neuroscience and Department of Microbiology, University of Oslo, Oslo, Norway
| | - Seetha V Balasingham
- Centre for Molecular Biology and Neuroscience and Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway.,Centre for Molecular Biology and Neuroscience and Department of Microbiology, University of Oslo, Oslo, Norway
| | - Jon K Laerdahl
- Bioinformatics Core Facility, Department of Informatics, University of Oslo, Oslo, Norway.,Centre for Molecular Biology and Neuroscience and Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway.,Centre for Molecular Biology and Neuroscience and Department of Microbiology, University of Oslo, Oslo, Norway
| | - Håvard Homberset
- Centre for Molecular Biology and Neuroscience and Department of Microbiology, University of Oslo, Oslo, Norway
| | - Per E Kristiansen
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | - Tone Tønjum
- Centre for Molecular Biology and Neuroscience and Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway.,Centre for Molecular Biology and Neuroscience and Department of Microbiology, University of Oslo, Oslo, Norway
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12
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Ordonez H, Shuman S. Mycobacterium smegmatis Lhr Is a DNA-dependent ATPase and a 3'-to-5' DNA translocase and helicase that prefers to unwind 3'-tailed RNA:DNA hybrids. J Biol Chem 2013; 288:14125-14134. [PMID: 23549043 DOI: 10.1074/jbc.m113.466854] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We are interested in the distinctive roster of helicases of Mycobacterium, a genus of the phylum Actinobacteria that includes the human pathogen Mycobacterium tuberculosis and its avirulent relative Mycobacterium smegmatis. Here, we identify and characterize M. smegmatis Lhr as the exemplar of a novel clade of superfamily II helicases, by virtue of its biochemical specificities and signature domain organization. Lhr is a 1507-amino acid monomeric nucleic acid-dependent ATPase that uses the energy of ATP hydrolysis to drive unidirectional 3'-to-5' translocation along single strand DNA and to unwind duplexes en route. The ATPase is more active in the presence of calcium than magnesium. ATP hydrolysis is triggered by either single strand DNA or single strand RNA, yet the apparent affinity for a DNA activator is 11-fold higher than for an RNA strand of identical size and nucleobase sequence. Lhr is 8-fold better at unwinding an RNA:DNA hybrid than it is at displacing a DNA:DNA duplex of identical nucleobase sequence. The truncated derivative Lhr-(1-856) is an autonomous ATPase, 3'-to-5' translocase, and RNA:DNA helicase. Lhr-(1-856) is 100-fold better RNA:DNA helicase than DNA:DNA helicase. Lhr homologs are found in bacteria representing eight different phyla, being especially prevalent in Actinobacteria (including M. tuberculosis) and Proteobacteria (including Escherichia coli).
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Affiliation(s)
- Heather Ordonez
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065.
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Thakur RS, Basavaraju S, Somyajit K, Jain A, Subramanya S, Muniyappa K, Nagaraju G. Evidence for the role of Mycobacterium tuberculosis RecG helicase in DNA repair and recombination. FEBS J 2013; 280:1841-60. [PMID: 23438087 DOI: 10.1111/febs.12208] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 02/05/2013] [Accepted: 02/18/2013] [Indexed: 11/28/2022]
Abstract
In order to survive and replicate in a variety of stressful conditions during its life cycle, Mycobacterium tuberculosis must possess mechanisms to safeguard the integrity of the genome. Although DNA repair and recombination related genes are thought to play key roles in the repair of damaged DNA in all organisms, so far only a few of them have been functionally characterized in the tubercle bacillus. In this study, we show that M. tuberculosis RecG (MtRecG) expression was induced in response to different genotoxic agents. Strikingly, expression of MtRecG in Escherichia coli ∆recG mutant strain provided protection against mitomycin C, methyl methane sulfonate and UV induced cell death. Purified MtRecG exhibited higher binding affinity for the Holliday junction (HJ) compared with a number of canonical recombinational DNA repair intermediates. Notably, although MtRecG binds at the core of the mobile and immobile HJs, and with higher binding affinity for the immobile HJ, branch migration was evident only in the case of the mobile HJ. Furthermore, immobile HJs stimulate MtRecG ATPase activity less efficiently than mobile HJs. In addition to HJ substrates, MtRecG exhibited binding affinity for a variety of branched DNA structures including three-way junctions, replication forks, flap structures, forked duplex and a D-loop structure, but demonstrated strong unwinding activity on replication fork and flap DNA structures. Together, these results support that MtRecG plays an important role in processes related to DNA metabolism under normal as well as stress conditions.
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Affiliation(s)
- Roshan S Thakur
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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