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Ahmed AM, Ibrahim AM, Yahia R, Shady NH, Mahmoud BK, Abdelmohsen UR, Fouad MA. Evaluation of the anti-infective potential of the seed endophytic fungi of Corchorus olitorius through metabolomics and molecular docking approach. BMC Microbiol 2023; 23:355. [PMID: 37980505 PMCID: PMC10656998 DOI: 10.1186/s12866-023-03092-5] [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: 03/31/2023] [Accepted: 10/27/2023] [Indexed: 11/20/2023] Open
Abstract
BACKGROUND Endophytic fungi are very rich sources of natural antibacterial and antifungal compounds. The main aim of this study is to isolate the fungal endophytes from the medicinal plant Corchorus olitorius seeds (F. Malvaceae), followed by antimicrobial screening against various bacterial and fungal strains. RESULTS Seven endophytic fungal strains belonging to different three genera were isolated, including Penicillium, Fusarium, and Aspergillus. The seven isolated endophytic strains revealed selective noticeable activity against Escherichia coli (ATCC25922) with varied IC50s ranging from 1.19 to 10 µg /mL, in which Aspergillus sp. (Ar 6) exhibited the strongest potency against E. coli (ATCC 25,922) and candida albicans (ATCC 10,231) with IC50s 1.19 and 15 µg /mL, respectively. Therefore, the chemical profiling of Aspergillus sp. (Ar 6) crude extract was performed using LC-HR-ESI-MS and led to the dereplication of sixteen compounds of various classes (1-16). In-silico analysis of the dereplicated metabolites led to highlighting the compounds responsible for the antimicrobial activity of Aspergillus sp. extract. Moreover, molecular docking showed the potential targets of the metabolites; Astellatol (5), Aspergillipeptide A (10), and Emericellamide C (14) against E. coli and C. albicans. CONCLUSION These results will expand the knowledge of endophytes and provide us with new approaches to face the global antibiotic resistance problem and the future production of undiscovered compounds different from the antibiotics classes.
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Affiliation(s)
- Arwa Mortada Ahmed
- Department of Pharmacognosy, Faculty of Pharmacy, Daraya University, New Minia City, 61111, Egypt
| | - Ayman M Ibrahim
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Daraya University, New Minia, 61111, Egypt
| | - Ramadan Yahia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Daraya University, New Minia City, Minia, Egypt
| | - Nourhan Hisham Shady
- Department of Pharmacognosy, Faculty of Pharmacy, Daraya University, New Minia City, 61111, Egypt
| | - Basma Khalaf Mahmoud
- Department of Pharmacognosy, Faculty of Pharmacy, Minia University, Minia, 61519, Egypt
| | - Usama Ramadan Abdelmohsen
- Department of Pharmacognosy, Faculty of Pharmacy, Daraya University, New Minia City, 61111, Egypt.
- Department of Pharmacognosy, Faculty of Pharmacy, Minia University, Minia, 61519, Egypt.
| | - Mostafa A Fouad
- Department of Pharmacognosy, Faculty of Pharmacy, Minia University, Minia, 61519, Egypt
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RecA and DNA recombination: a review of molecular mechanisms. Biochem Soc Trans 2020; 47:1511-1531. [PMID: 31654073 DOI: 10.1042/bst20190558] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/18/2019] [Accepted: 09/25/2019] [Indexed: 11/17/2022]
Abstract
Recombinases are responsible for homologous recombination and maintenance of genome integrity. In Escherichia coli, the recombinase RecA forms a nucleoprotein filament with the ssDNA present at a DNA break and searches for a homologous dsDNA to use as a template for break repair. During the first step of this process, the ssDNA is bound to RecA and stretched into a Watson-Crick base-paired triplet conformation. The RecA nucleoprotein filament also contains ATP and Mg2+, two cofactors required for RecA activity. Then, the complex starts a homology search by interacting with and stretching dsDNA. Thanks to supercoiling, intersegment sampling and RecA clustering, a genome-wide homology search takes place at a relevant metabolic timescale. When a region of homology 8-20 base pairs in length is found and stabilized, DNA strand exchange proceeds, forming a heteroduplex complex that is resolved through a combination of DNA synthesis, ligation and resolution. RecA activities can take place without ATP hydrolysis, but this latter activity is necessary to improve and accelerate the process. Protein flexibility and monomer-monomer interactions are fundamental for RecA activity, which functions cooperatively. A structure/function relationship analysis suggests that the recombinogenic activity can be improved and that recombinases have an inherently large recombination potential. Understanding this relationship is essential for designing RecA derivatives with enhanced activity for biotechnology applications. For example, this protein is a major actor in the recombinase polymerase isothermal amplification (RPA) used in point-of-care diagnostics.
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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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Patoli BB, Winter JA, Patoli AA, Delahay RM, Bunting KA. Co-expression and purification of the RadA recombinase with the RadB paralog from Haloferax volcanii yields heteromeric ring-like structures. Microbiology (Reading) 2017; 163:1802-1811. [DOI: 10.1099/mic.0.000562] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Bushra B. Patoli
- School of Biology, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
- Present address: Institute of Microbiology, University of Sindh, Jamshoro, Pakistan
| | - Jody A. Winter
- School of Biology, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
- Present address: Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - Atif A. Patoli
- School of Biology, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
- Present address: Institute of Microbiology, University of Sindh, Jamshoro, Pakistan
| | - Robin M. Delahay
- School of Medicine, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Karen A. Bunting
- School of Biology, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
- Present address: Albumedix Ltd, Nottingham, NG7 1FD, UK
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5
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Leite WC, Galvão CW, Saab SC, Iulek J, Etto RM, Steffens MBR, Chitteni-Pattu S, Stanage T, Keck JL, Cox MM. Structural and Functional Studies of H. seropedicae RecA Protein - Insights into the Polymerization of RecA Protein as Nucleoprotein Filament. PLoS One 2016; 11:e0159871. [PMID: 27447485 PMCID: PMC4957752 DOI: 10.1371/journal.pone.0159871] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/08/2016] [Indexed: 11/18/2022] Open
Abstract
The bacterial RecA protein plays a role in the complex system of DNA damage repair. Here, we report the functional and structural characterization of the Herbaspirillum seropedicae RecA protein (HsRecA). HsRecA protein is more efficient at displacing SSB protein from ssDNA than Escherichia coli RecA protein. HsRecA also promotes DNA strand exchange more efficiently. The three dimensional structure of HsRecA-ADP/ATP complex has been solved to 1.7 Å resolution. HsRecA protein contains a small N-terminal domain, a central core ATPase domain and a large C-terminal domain, that are similar to homologous bacterial RecA proteins. Comparative structural analysis showed that the N-terminal polymerization motif of archaeal and eukaryotic RecA family proteins are also present in bacterial RecAs. Reconstruction of electrostatic potential from the hexameric structure of HsRecA-ADP/ATP revealed a high positive charge along the inner side, where ssDNA is bound inside the filament. The properties of this surface may explain the greater capacity of HsRecA protein to bind ssDNA, forming a contiguous nucleoprotein filament, displace SSB and promote DNA exchange relative to EcRecA. Our functional and structural analyses provide insight into the molecular mechanisms of polymerization of bacterial RecA as a helical nucleoprotein filament.
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Affiliation(s)
- Wellington C. Leite
- Department of Physics, Ponta Grossa State University (UEPG), Av. Carlos Cavalcanti, 4748, CEP. 84.030–900, Ponta Grossa, PR, Brazil
- * E-mail: (MC); (WL)
| | - Carolina W. Galvão
- Department of Structural and Molecular Biology and Genetics, Ponta Grossa State University (UEPG), CEP 84030–900, Ponta Grossa, PR, Brazil
| | - Sérgio C. Saab
- Department of Physics, Ponta Grossa State University (UEPG), Av. Carlos Cavalcanti, 4748, CEP. 84.030–900, Ponta Grossa, PR, Brazil
| | - Jorge Iulek
- Department of Chemistry, Ponta Grossa State University (UEPG), CEP 84030–900, Ponta Grossa, PR, Brazil
| | - Rafael M. Etto
- Department of Chemistry, Ponta Grossa State University (UEPG), CEP 84030–900, Ponta Grossa, PR, Brazil
| | - Maria B. R. Steffens
- Department of Biochemistry and Molecular Biology, Federal University of Parana, CEP 81531–980 Curitiba, Brazil
| | - Sindhu Chitteni-Pattu
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI, 53706–1544, United States of America
| | - Tyler Stanage
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI, 53706–1544, United States of America
| | - James L. Keck
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI, 53706, United States of America
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI, 53706–1544, United States of America
- * E-mail: (MC); (WL)
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Shivange G, Monisha M, Nigam R, Kodipelli N, Anindya R. RecA stimulates AlkB-mediated direct repair of DNA adducts. Nucleic Acids Res 2016; 44:8754-8763. [PMID: 27378775 PMCID: PMC5062977 DOI: 10.1093/nar/gkw611] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 06/28/2016] [Indexed: 11/16/2022] Open
Abstract
The Escherichia coli AlkB protein is a 2-oxoglutarate/Fe(II)-dependent demethylase that repairs alkylated single stranded and double stranded DNA. Immunoaffinity chromatography coupled with mass spectrometry identified RecA, a key factor in homologous recombination, as an AlkB-associated protein. The interaction between AlkB and RecA was validated by yeast two-hybrid assay; size-exclusion chromatography and standard pull down experiment and was shown to be direct and mediated by the N-terminal domain of RecA. RecA binding results AlkB–RecA heterodimer formation and RecA–AlkB repairs alkylated DNA with higher efficiency than AlkB alone.
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Affiliation(s)
- Gururaj Shivange
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, 502285 Hyderabad, Telangana, India
| | - Mohan Monisha
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, 502285 Hyderabad, Telangana, India
| | - Richa Nigam
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, 502285 Hyderabad, Telangana, India
| | - Naveena Kodipelli
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, 502285 Hyderabad, Telangana, India
| | - Roy Anindya
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, 502285 Hyderabad, Telangana, India
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Prentiss M, Prévost C, Danilowicz C. Structure/function relationships in RecA protein-mediated homology recognition and strand exchange. Crit Rev Biochem Mol Biol 2015; 50:453-76. [DOI: 10.3109/10409238.2015.1092943] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Boyer B, Ezelin J, Poulain P, Saladin A, Zacharias M, Robert CH, Prévost C. An integrative approach to the study of filamentous oligomeric assemblies, with application to RecA. PLoS One 2015; 10:e0116414. [PMID: 25785454 PMCID: PMC4364692 DOI: 10.1371/journal.pone.0116414] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 12/09/2014] [Indexed: 11/19/2022] Open
Abstract
Oligomeric macromolecules in the cell self-organize into a wide variety of geometrical motifs such as helices, rings or linear filaments. The recombinase proteins involved in homologous recombination present many such assembly motifs. Here, we examine in particular the polymorphic characteristics of RecA, the most studied member of the recombinase family, using an integrative approach that relates local modes of monomer/monomer association to the global architecture of their screw-type organization. In our approach, local modes of association are sampled via docking or Monte Carlo simulations. This enables shedding new light on fiber morphologies that may be adopted by the RecA protein. Two distinct RecA helical morphologies, the so-called "extended" and "compressed" forms, are known to play a role in homologous recombination. We investigate the variability within each form in terms of helical parameters and steric accessibility. We also address possible helical discontinuities in RecA filaments due to multiple monomer-monomer association modes. By relating local interface organization to global filament morphology, the strategies developed here to study RecA self-assembly are particularly well suited to other DNA-binding proteins and to filamentous protein assemblies in general.
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Affiliation(s)
- Benjamin Boyer
- Laboratoire de Biochimie Théorique, CNRS, UPR 9080, Univ Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris, France
- MTI, INSERM UMR-M 973, Université Paris Diderot-Paris 7, Bât Lamarck, 35 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Johann Ezelin
- Laboratoire de Biochimie Théorique, CNRS, UPR 9080, Univ Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Pierre Poulain
- DSIMB team, Inserm UMR-S 665 and Univ. Paris Diderot, Sorbonne Paris Cité, INTS, 6 rue Alexandre Cabanel, 75015 Paris, France
- Ets Poulain, Pointe-Noire, Republic of Congo
| | - Adrien Saladin
- MTI, INSERM UMR-M 973, Université Paris Diderot-Paris 7, Bât Lamarck, 35 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Martin Zacharias
- Technische Universität München, Physik-Department, James-Franck-Str. 1, 85748 Garching, Germany
| | - Charles H. Robert
- Laboratoire de Biochimie Théorique, CNRS, UPR 9080, Univ Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Chantal Prévost
- Laboratoire de Biochimie Théorique, CNRS, UPR 9080, Univ Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris, France
- * E-mail:
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9
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Shi L, Pigeonneau N, Ventroux M, Derouiche A, Bidnenko V, Mijakovic I, Noirot-Gros MF. Protein-tyrosine phosphorylation interaction network in Bacillus subtilis reveals new substrates, kinase activators and kinase cross-talk. Front Microbiol 2014; 5:538. [PMID: 25374563 PMCID: PMC4205851 DOI: 10.3389/fmicb.2014.00538] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 09/26/2014] [Indexed: 01/28/2023] Open
Abstract
Signal transduction in eukaryotes is generally transmitted through phosphorylation cascades that involve a complex interplay of transmembrane receptors, protein kinases, phosphatases and their targets. Our previous work indicated that bacterial protein-tyrosine kinases and phosphatases may exhibit similar properties, since they act on many different substrates. To capture the complexity of this phosphorylation-based network, we performed a comprehensive interactome study focused on the protein-tyrosine kinases and phosphatases in the model bacterium Bacillus subtilis. The resulting network identified many potential new substrates of kinases and phosphatases, some of which were experimentally validated. Our study highlighted the role of tyrosine and serine/threonine kinases and phosphatases in DNA metabolism, transcriptional control and cell division. This interaction network reveals significant crosstalk among different classes of kinases. We found that tyrosine kinases can bind to several modulators, transmembrane or cytosolic, consistent with a branching of signaling pathways. Most particularly, we found that the division site regulator MinD can form a complex with the tyrosine kinase PtkA and modulate its activity in vitro. In vivo, it acts as a scaffold protein which anchors the kinase at the cell pole. This network highlighted a role of tyrosine phosphorylation in the spatial regulation of the Z-ring during cytokinesis.
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Affiliation(s)
- Lei Shi
- Institut National de la Recherche Agronomique, UMR1319 Micalis Jouy-en-Josas, France ; Systems and Synthetic Biology, Department of Chemical and Biological Engineering, Chalmers University of Technology Gothenburg, Sweden
| | - Nathalie Pigeonneau
- Institut National de la Recherche Agronomique, UMR1319 Micalis Jouy-en-Josas, France
| | - Magali Ventroux
- Institut National de la Recherche Agronomique, UMR1319 Micalis Jouy-en-Josas, France
| | - Abderahmane Derouiche
- Institut National de la Recherche Agronomique, UMR1319 Micalis Jouy-en-Josas, France ; Systems and Synthetic Biology, Department of Chemical and Biological Engineering, Chalmers University of Technology Gothenburg, Sweden
| | - Vladimir Bidnenko
- Systems and Synthetic Biology, Department of Chemical and Biological Engineering, Chalmers University of Technology Gothenburg, Sweden
| | - Ivan Mijakovic
- Institut National de la Recherche Agronomique, UMR1319 Micalis Jouy-en-Josas, France ; Systems and Synthetic Biology, Department of Chemical and Biological Engineering, Chalmers University of Technology Gothenburg, Sweden
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Burgos R, Totten PA. MG428 is a novel positive regulator of recombination that triggers mgpB and mgpC gene variation in Mycoplasma genitalium. Mol Microbiol 2014; 94:290-306. [PMID: 25138908 DOI: 10.1111/mmi.12760] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2014] [Indexed: 01/01/2023]
Abstract
The human pathogen Mycoplasma genitalium employs homologous recombination to generate antigenic diversity in the immunodominant MgpB and MgpC proteins. Only recently, some of the molecular factors involved in this process have been characterized, but nothing is known about its regulation. Here, we show that M. genitalium expresses N-terminally truncated RecA isoforms via alternative translation initiation, but only the full-length protein is essential for gene variation. We also demonstrate that overexpression of MG428 positively regulates the expression of recombination genes, including recA, ruvA, ruvB and ORF2, a gene of unknown function co-transcribed with ruvAB. The co-ordinated induction of these genes correlated with an increase of mgpBC gene variation. In contrast, cells lacking MG428 were unable to generate variants despite expressing normal levels of RecA. Similarly, deletion analyses of the recA upstream region defined sequences required for gene variation without abolishing RecA expression. The requirement of these sequences is consistent with the presence of promoter elements associated with MG428-dependent recA induction. Sequences upstream of recA also influence the relative abundance of RecA isoforms, possibly through translational regulation. Overall, these results suggest that MG428 is a positive regulator of recombination and that precise control of recA expression is required to initiate mgpBC variation.
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Affiliation(s)
- Raul Burgos
- Department of Medicine, Division of Infectious Diseases, University of Washington, Seattle, WA, 98104, USA
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Metrick MA, Temple JE, MacDonald G. The effects of buffers and pH on the thermal stability, unfolding and substrate binding of RecA. Biophys Chem 2013; 184:29-36. [DOI: 10.1016/j.bpc.2013.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/06/2013] [Accepted: 08/06/2013] [Indexed: 10/26/2022]
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Chen LT, Wang AHJ. A rationally designed peptide enhances homologous recombination in vitro and resistance to DNA damaging agents in vivo. Nucleic Acids Res 2010; 38:4361-71. [PMID: 20308162 PMCID: PMC2910059 DOI: 10.1093/nar/gkq182] [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] [Indexed: 11/25/2022] Open
Abstract
The RecA family of proteins is essential in homologous recombination, a critical step in DNA repair. Here, we report that a rationally-designed small peptide based on the crystal structure of Escherichia coli RecA–DNA complex can promote homologous recombination through the enhancement of both RecA-mediated strand assimilation and three-strand exchange activity. Among 17 peptides tested, peptide #3 with the amino acid sequence of IRFLTARRR has the most potent activity in promoting the RecA-mediated D-loop formation by ∼7.2-fold at 37°C. Other peptides such as IRFLTAKKK and IRLLTARRR also have similar, albeit lower, activities. Therefore, hydrophobicity and poly-positive charges, and the space between them in those small peptides are crucial features for such activities. The enhancement of recombination by these peptides appears to be a general phenomenon as similar results were seen by using different plasmids. Remarkably, peptide #3 alone without RecA can also promote the D-loop formation at elevated temperature. Cell viability assays showed that the peptide elevates mammalian cell resistance to two cytotoxic DNA drugs, cisplatin and doxorubicin. The rescue of viability may result from increased DNA repair efficiency. Such peptides may find future biological applications.
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Affiliation(s)
- Li-Tzu Chen
- Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
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