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Crespo I, Bernardo N, Cuppari A, Malfois M, Boer DR. Structural and biochemical characterization of the relaxosome auxiliary proteins encoded on the Bacillus subtilis plasmid pLS20. Comput Struct Biotechnol J 2022; 20:757-765. [PMID: 35198129 PMCID: PMC8829557 DOI: 10.1016/j.csbj.2021.12.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 12/22/2021] [Accepted: 12/30/2021] [Indexed: 12/03/2022] Open
Abstract
Bacterial conjugation is an important route for horizontal gene transfer. The initial step in this process involves a macromolecular protein-DNA complex called the relaxosome, which in plasmids consists of the origin of transfer (oriT) and several proteins that prepare the transfer. The relaxosome protein named relaxase introduces a nick in one of the strands of the oriT to initiate the process. Additional relaxosome proteins can exist. Recently, several relaxosome proteins encoded on the Bacillus subtilis plasmid pLS20 were identified, including the relaxase, named RelpLS20, and two auxiliary DNA-binding factors, named Aux1pLS20 and Aux2pLS20. Here, we extend this characterization in order to define their function. We present the low-resolution SAXS envelope of the Aux1pLS20 and the atomic X-ray structure of the C-terminal domain of Aux2pLS20. We also study the interactions between the auxiliary proteins and the full-length RelpLS20, as well as its separate domains. The results show that the quaternary structure of the auxiliary protein Aux1pLS20 involves a tetramer, as previously determined. The crystal structure of the C-terminal domain of Aux2pLS20 shows that it forms a tetramer and suggests that it is an analog of TraMpF of plasmid F. This is the first evidence of the existence of a TraMpF analog in gram positive conjugative systems, although, unlike other TraMpF analogs, Aux2pLS20 does not interact with the relaxase. Aux1pLS20 interacts with the C-terminal domain, but not the N-terminal domain, of the relaxase RelpLS20. Thus, the pLS20 relaxosome exhibits some unique features despite the apparent similarity to some well-studied G- conjugation systems.
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2
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Iqbal N, Mukhtar MU, Yang J, Niu Q, Li Z, Zhao S, Zhao Y, Guan G, Liu Z, Yin H. Identification and evaluation of midgut protein RL12 of Dermacentor silvarum interacting with Anaplasma ovis VirD4. Ticks Tick Borne Dis 2021; 12:101677. [PMID: 33549977 DOI: 10.1016/j.ttbdis.2021.101677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 01/16/2021] [Accepted: 01/17/2021] [Indexed: 11/15/2022]
Abstract
Anaplasma ovis, a tick-borne intra-erythrocytic Gram-negative bacterium, is a causative agent of ovine anaplasmosis. It is known that Dermacentor ticks act as biological vectors for A. ovis. VirD4 is the machine component of Type IV Secretion System of A. ovis. To better understand the pathogen-vector interaction, VirD4 was used as a bait protein for screening midgut proteins of Dermacentor silvarum via yeast two-hybrid mating assay. As a result, a ribosomal protein RL12 was identified from the midgut cDNA library of D. silvarum. For further validation, using in vitro Glutathione S-transferase (GST) pull-down assay, interaction between the proteins, GST-RL12 and HIS-VirD4, was observed in Western blot analysis. The study is first of its kind reporting a D. silvarum midgut protein interaction with VirD4 from A. ovis. Functional annotations showed some important cellular processes are attributed to the protein, particularly in the stringent response and biogenesis. The results of the study suggest the involvement of the VirD4-RL12 interaction in the regulation of signaling pathways, which is a tool for understanding the pathogen-vector interaction.
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Affiliation(s)
- Naveed Iqbal
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Muhammad Uzair Mukhtar
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Jifei Yang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Qingli Niu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Zhi Li
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Shuaiyang Zhao
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Yaru Zhao
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Guiquan Guan
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Zhijie Liu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China.
| | - Hong Yin
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, PR China.
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3
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Li C, Ban X, Zhang Y, Gu Z, Hong Y, Cheng L, Tang X, Li Z. Rational Design of Disulfide Bonds for Enhancing the Thermostability of the 1,4-α-Glucan Branching Enzyme from Geobacillus thermoglucosidans STB02. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:13791-13797. [PMID: 33166453 DOI: 10.1021/acs.jafc.0c04798] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Disulfide bonds play crucial roles in thermostabilization, recognition, or activation of proteins. They are vital in maintaining the respective conformations of globular structures, thereby enhancing thermostability. Bioinformatic approaches provide practical strategies to build disulfide bonds based on structural information. We constructed nine mutants by rational analysis of the 1,4-α-glucan branching enzyme (EC 2.4.1.18) from Geobacillus thermoglucosidans STB02, which catalyzes the synthesis of α-1,6-glucosidic bonds by acting on α-(1,4) and/or α-(1,6) glucosidic linkages. Four of the mutations enhanced thermostability, and five of them had adverse or negligible effects on stability. Circular dichroism spectra and intrinsic fluorescence analysis showed that introducing disulfide bonds might only affect secondary structures. The results also demonstrated that the distances of Cα carbons and thiol groups, as well as the sequence between the two cysteines, need to be considered when designing disulfide bonds.
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Affiliation(s)
- Caiming Li
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
- USDA, Agricultural Research Service, WRRC, 800 Buchanan Street, Albany, California 94710, United States
| | - Xiaofeng Ban
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Yuzhu Zhang
- USDA, Agricultural Research Service, WRRC, 800 Buchanan Street, Albany, California 94710, United States
| | - Zhengbiao Gu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
| | - Yan Hong
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
| | - Li Cheng
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
| | - Xiaoshu Tang
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- National Engineering Research Center for Functional Food, Wuxi 214122, China
| | - Zhaofeng Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
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4
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Álvarez-Rodríguez I, Arana L, Ugarte-Uribe B, Gómez-Rubio E, Martín-Santamaría S, Garbisu C, Alkorta I. Type IV Coupling Proteins as Potential Targets to Control the Dissemination of Antibiotic Resistance. Front Mol Biosci 2020; 7:201. [PMID: 32903459 PMCID: PMC7434980 DOI: 10.3389/fmolb.2020.00201] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/27/2020] [Indexed: 12/18/2022] Open
Abstract
The increase of infections caused by multidrug-resistant bacteria, together with the loss of effectiveness of currently available antibiotics, represents one of the most serious threats to public health worldwide. The loss of human lives and the economic costs associated to the problem of the dissemination of antibiotic resistance require immediate action. Bacteria, known by their great genetic plasticity, are capable not only of mutating their genes to adapt to disturbances and environmental changes but also of acquiring new genes that allow them to survive in hostile environments, such as in the presence of antibiotics. One of the major mechanisms responsible for the horizontal acquisition of new genes (e.g., antibiotic resistance genes) is bacterial conjugation, a process mediated by mobile genetic elements such as conjugative plasmids and integrative conjugative elements. Conjugative plasmids harboring antibiotic resistance genes can be transferred from a donor to a recipient bacterium in a process that requires physical contact. After conjugation, the recipient bacterium not only harbors the antibiotic resistance genes but it can also transfer the acquired plasmid to other bacteria, thus contributing to the spread of antibiotic resistance. Conjugative plasmids have genes that encode all the proteins necessary for the conjugation to take place, such as the type IV coupling proteins (T4CPs) present in all conjugative plasmids. Type VI coupling proteins constitute a heterogeneous family of hexameric ATPases that use energy from the ATP hydrolysis for plasmid transfer. Taking into account their essential role in bacterial conjugation, T4CPs are attractive targets for the inhibition of bacterial conjugation and, concomitantly, the limitation of antibiotic resistance dissemination. This review aims to compile present knowledge on T4CPs as a starting point for delving into their molecular structure and functioning in future studies. Likewise, the scientific literature on bacterial conjugation inhibitors has been reviewed here, in an attempt to elucidate the possibility of designing T4CP-inhibitors as a potential solution to the dissemination of multidrug-resistant bacteria.
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Affiliation(s)
- Itxaso Álvarez-Rodríguez
- Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
| | - Lide Arana
- Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
| | - Begoña Ugarte-Uribe
- Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
| | - Elena Gómez-Rubio
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas, CIB-CSIC, Madrid, Spain
| | - Sonsoles Martín-Santamaría
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas, CIB-CSIC, Madrid, Spain
| | - Carlos Garbisu
- Department of Conservation of Natural Resources, Soil Microbial Ecology Group, NEIKER - Basque Institute for Agricultural Research and Development, Basque Research and Technology Alliance (BRTA), Parque Cient fico y Tecnológico de Bizkaia, Derio, Spain
| | - Itziar Alkorta
- Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
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Li YG, Christie PJ. The TraK accessory factor activates substrate transfer through the pKM101 type IV secretion system independently of its role in relaxosome assembly. Mol Microbiol 2020; 114:214-229. [PMID: 32239779 DOI: 10.1111/mmi.14507] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 03/24/2020] [Indexed: 12/12/2022]
Abstract
A large subfamily of the type IV secretion systems (T4SSs), termed the conjugation systems, transmit mobile genetic elements (MGEs) among many bacterial species. In the initiating steps of conjugative transfer, DNA transfer and replication (Dtr) proteins assemble at the origin-of-transfer (oriT) sequence as the relaxosome, which nicks the DNA strand destined for transfer and couples the nicked substrate with the VirD4-like substrate receptor. Here, we defined contributions of the Dtr protein TraK, a predicted member of the Ribbon-Helix-Helix (RHH) family of DNA-binding proteins, to transfer of DNA and protein substrates through the pKM101-encoded T4SS. Using a combination of cross-linking/affinity pull-downs and two-hybrid assays, we determined that TraK self-associates as a probable tetramer and also forms heteromeric contacts with pKM101-encoded TraI relaxase, VirD4-like TraJ receptor, and VirB11-like and VirB4-like ATPases, TraG and TraB, respectively. TraK also promotes stable TraJ-TraB complex formation and stimulates binding of TraI with TraB. Finally, TraK is required for or strongly stimulates the transfer of cognate (pKM101, TraI relaxase) and noncognate (RSF1010, MobA relaxase) substrates. We propose that TraK functions not only to nucleate pKM101 relaxosome assembly, but also to activate the TrapKM101 T4SS via interactions with the ATPase energy center positioned at the channel entrance.
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Affiliation(s)
- Yang Grace Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, TX, USA
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, TX, USA
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6
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Lorenzo-Díaz F, Fernández-López C, Guillén-Guío B, Bravo A, Espinosa M. Relaxase MobM Induces a Molecular Switch at Its Cognate Origin of Transfer. Front Mol Biosci 2018; 5:17. [PMID: 29600250 PMCID: PMC5863519 DOI: 10.3389/fmolb.2018.00017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/09/2018] [Indexed: 11/13/2022] Open
Abstract
The MOBV1 family of relaxases is broadly distributed in plasmids and other mobile genetic elements isolated from staphylococci, enterococci, and streptococci. The prototype of this family is protein MobM encoded by the streptococcal promiscuous plasmid pMV158. MobM cleaves the phosphodiester bond of a specific dinucleotide within the origin of transfer (oriT) to initiate conjugative transfer. Differently from other relaxases, MobM and probably other members of the family, cleaves its target single-stranded DNA through a histidine residue rather than the commonly used tyrosine. The oriT of the MOBV1 family differs from other well-known conjugative systems since it has sequences with three inverted repeats, which were predicted to generate three mutually-exclusive hairpins on supercoiled DNA. In this work, such hypothesis was evaluated through footprinting experiments on supercoiled plasmid DNA. We have found a change in hairpin extrusion mediated by protein MobM. This conformational change involves a shift from the main hairpin generated on “naked” DNA to a different hairpin in which the nick site is positioned in a single-stranded configuration. Our results indicate that the oriTpMV158 acts as a molecular switch in which, depending on the inverted repeat recognized by MobM, pMV158 mobilization could be turned “on” or “off.”
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.,Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | | | - Beatriz Guillén-Guío
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.,Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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7
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Tran F, Boedicker JQ. Genetic cargo and bacterial species set the rate of vesicle-mediated horizontal gene transfer. Sci Rep 2017; 7:8813. [PMID: 28821711 PMCID: PMC5562762 DOI: 10.1038/s41598-017-07447-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/27/2017] [Indexed: 12/22/2022] Open
Abstract
Most bacteria release extracellular vesicles (EVs). Recent studies have found these vesicles are capable of gene delivery, however the consequences of vesicle-mediated transfer on the patterns and rates of gene flow within microbial communities remains unclear. Previous studies have not determined the impact of both the genetic cargo and the donor and recipient species on the rate of vesicle-mediated gene exchange. This report examines the potential for EVs as a mechanism of gene transfer within heterogeneous microbial populations. EVs were harvested from three species of Gram-negative microbes carrying different plasmids. The dynamics of gene transfer into recipient species was measured. This study demonstrates that vesicles enable gene exchange between five species of Gram-negative bacteria, and that the identity of the genetic cargo, donor strain, and recipient strain all influence gene transfer rates. Each species released and acquired vesicles containing genetic material to a variable degree, and the transfer rate did not correlate with the relatedness of the donor and recipient species. The results suggest that EVs may be a general mechanism to exchange non-specialized genetic cargo between bacterial species.
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Affiliation(s)
- Frances Tran
- University of Southern California, Department of Biological Sciences, Seaver Science Center (SSC) 212, 920 Bloom Walk, Los Angeles, CA, 90089, USA
| | - James Q Boedicker
- University of Southern California, Department of Biological Sciences, Seaver Science Center (SSC) 212, 920 Bloom Walk, Los Angeles, CA, 90089, USA.
- University of Southern California, Department of Physics and Astronomy, Seaver Science Center (SSC) 212, 920 Bloom Walk, Los Angeles, CA, 90089, USA.
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8
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Structural basis of a histidine-DNA nicking/joining mechanism for gene transfer and promiscuous spread of antibiotic resistance. Proc Natl Acad Sci U S A 2017; 114:E6526-E6535. [PMID: 28739894 DOI: 10.1073/pnas.1702971114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Relaxases are metal-dependent nucleases that break and join DNA for the initiation and completion of conjugative bacterial gene transfer. Conjugation is the main process through which antibiotic resistance spreads among bacteria, with multidrug-resistant staphylococci and streptococci infections posing major threats to human health. The MOBV family of relaxases accounts for approximately 85% of all relaxases found in Staphylococcus aureus isolates. Here, we present six structures of the MOBV relaxase MobM from the promiscuous plasmid pMV158 in complex with several origin of transfer DNA fragments. A combined structural, biochemical, and computational approach reveals that MobM follows a previously uncharacterized histidine/metal-dependent DNA processing mechanism, which involves the formation of a covalent phosphoramidate histidine-DNA adduct for cell-to-cell transfer. We discuss how the chemical features of the high-energy phosphorus-nitrogen bond shape the dominant position of MOBV histidine relaxases among small promiscuous plasmids and their preference toward Gram-positive bacteria.
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9
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Kambouris ME, Markogiannakis A, Arabatzis M, Manoussopoulos Y, Kantzanou M, Velegraki A. Wireless electrostimulation: a new approach in combating infection? Future Microbiol 2017; 12:255-265. [DOI: 10.2217/fmb-2017-0157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Electrostimulation (ES), hitherto successfully employed in wound treatment, has shown potential in antimicrobial applications, suggesting its use as synergistic to or replacement of antibiotics. The differential susceptibility of pathogens and host tissue and organs to various ES modalities might allow selective use against specific infections. The use of ES is cheaper in terms of development/testing, routine application and environmental footprint. If extensive substitution of chemical compounds is achieved, the development of resistance might be reversed through negative selection. A promising setup of ES seems to be the noncontact current transfer, due to low amperage similar to innate bioelectricity, painlessness, simple logistics and low risk for treatment-caused infection.
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Affiliation(s)
| | | | - Michael Arabatzis
- Mycology Research Laboratory, Department of Microbiology, Medical School, National and Kapodistrian University of Athens 11527, Greece
| | | | - Maria Kantzanou
- Department of Hygiene, Epidemiology & Medical Statistics, National Retrovirus Reference Center, Medical School, National and Kapodistrian University of Athens 11527, Greece
| | - Aristea Velegraki
- Mycology Research Laboratory, Department of Microbiology, Medical School, National and Kapodistrian University of Athens 11527, Greece
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10
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Boyd D, Taylor G, Fuller J, Bryce E, Embree J, Gravel D, Katz K, Kibsey P, Kuhn M, Langley J, Mataseje L, Mitchell R, Roscoe D, Simor A, Thomas E, Turgeon N, Mulvey M. Complete Sequence of Four Multidrug-Resistant MOBQ1 Plasmids Harboring blaGES-5 Isolated from Escherichia coli and Serratia marcescens Persisting in a Hospital in Canada. Microb Drug Resist 2014; 21:253-60. [PMID: 25545311 DOI: 10.1089/mdr.2014.0205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The usefulness of carbapenems for gram-negative infections is becoming compromised by organisms harboring carbapenemases, enzymes which can hydrolyze the drug. Currently KPC (class A), NDM (class B), and OXA-48 types (class D) are the most globally widespread carbapenemases. However, among the GES-type class A extended-spectrum β-lactamases (ESBLs) there are variants that hydrolyze carbapenems, with blaGES-5 being the most common. Two Escherichia coli and two Serratia marcescens harboring blaGES-5 on plasmids were isolated by the Canadian Nosocomial Infection Surveillance Program (CNISP) from four different patients in a single hospital over a 2-year period. Complete sequencing of the blaGES-5 plasmids indicated that all four had nearly identical backbones consisting of genes for replication, partitioning, and stability, but contained variant accessory regions consisting of mobile elements and antimicrobial resistance genes. The plasmids were of a novel replicon type, but belonged to the MOBQ1 group based on relaxase sequences, and appeared to be mobilizable, but not self-transmissible. Considering the time periods of bacterial isolation, it would appear the blaGES-5 plasmid has persisted in an environmental niche for at least 2 years in the hospital. This has implications for infection control and clinical care when it is transferred to clinically relevant gram-negative organisms.
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Affiliation(s)
- David Boyd
- 1National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Geoffrey Taylor
- 2Faculty of Medicine and Dentistry, University of Alberta Hospital, Edmonton, AB, Canada
| | - Jeff Fuller
- 2Faculty of Medicine and Dentistry, University of Alberta Hospital, Edmonton, AB, Canada
| | | | - Joanne Embree
- 4Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Denise Gravel
- 5Centre for Communicable Disease and Infection Control, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Kevin Katz
- 6Infection Prevention and Control, North York General Hospital, Toronto, ON, Canada
| | - Pamela Kibsey
- 7Department of Laboratory Medicine, Victoria General Hospital, Victoria, BC, Canada
| | | | | | - Laura Mataseje
- 1National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Robyn Mitchell
- 5Centre for Communicable Disease and Infection Control, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Diane Roscoe
- 3Vancouver General Hospital, Vancouver, BC, Canada
| | - Andrew Simor
- 10Infectious Diseases Division, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Eva Thomas
- 11Children's and Women's Health Centre, Vancouver, BC, Canada
| | | | - Michael Mulvey
- 1National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
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11
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Cabezón E, Ripoll-Rozada J, Peña A, de la Cruz F, Arechaga I. Towards an integrated model of bacterial conjugation. FEMS Microbiol Rev 2014; 39:81-95. [PMID: 25154632 DOI: 10.1111/1574-6976.12085] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Bacterial conjugation is one of the main mechanisms for horizontal gene transfer. It constitutes a key element in the dissemination of antibiotic resistance and virulence genes to human pathogenic bacteria. DNA transfer is mediated by a membrane-associated macromolecular machinery called Type IV secretion system (T4SS). T4SSs are involved not only in bacterial conjugation but also in the transport of virulence factors by pathogenic bacteria. Thus, the search for specific inhibitors of different T4SS components opens a novel approach to restrict plasmid dissemination. This review highlights recent biochemical and structural findings that shed new light on the molecular mechanisms of DNA and protein transport by T4SS. Based on these data, a model for pilus biogenesis and substrate transfer in conjugative systems is proposed. This model provides a renewed view of the mechanism that might help to envisage new strategies to curb the threating expansion of antibiotic resistance.
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Affiliation(s)
- Elena Cabezón
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC, (Universidad de Cantabria, CSIC) Santander, Spain
| | - Jorge Ripoll-Rozada
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC, (Universidad de Cantabria, CSIC) Santander, Spain
| | - Alejandro Peña
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC, (Universidad de Cantabria, CSIC) Santander, Spain
| | - Fernando de la Cruz
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC, (Universidad de Cantabria, CSIC) Santander, Spain
| | - Ignacio Arechaga
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC, (Universidad de Cantabria, CSIC) Santander, Spain
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12
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Lorenzo-Díaz F, Fernández-López C, Garcillán-Barcia MP, Espinosa M. Bringing them together: plasmid pMV158 rolling circle replication and conjugation under an evolutionary perspective. Plasmid 2014; 74:15-31. [PMID: 24942190 PMCID: PMC7103276 DOI: 10.1016/j.plasmid.2014.05.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 11/29/2022]
Abstract
Rolling circle-replicating plasmids constitute a vast family that is particularly abundant in, but not exclusive of, Gram-positive bacteria. These plasmids are constructed as cassettes that harbor genes involved in replication and its control, mobilization, resistance determinants and one or two origins of lagging strand synthesis. Any given plasmid may contain all, some, or just only the replication cassette. We discuss here the family of the promiscuous streptococcal plasmid pMV158, with emphasis on its mobilization functions: the product of the mobM gene, prototype of the MOBV relaxase family, and its cognate origin of transfer, oriT. Amongst the subfamily of MOBV1 plasmids, three groups of oriT sequences, represented by plasmids pMV158, pT181, and p1414 were identified. In the same subfamily, we found four types of single-strand origins, namely ssoA, ssoU, ssoW, and ssoT. We found that plasmids of the rolling-circle Rep_2 family (to which pMV158 belongs) are more frequently found in Lactobacillales than in any other bacterial order, whereas Rep_1 initiators seemed to prefer hosts included in the Bacillales order. In parallel, MOBV1 relaxases associated with Rep_2 initiators tended to cluster separately from those linked to Rep_1 plasmids. The updated inventory of MOBV1 plasmids still contains exclusively mobilizable elements, since no genes associated with conjugative transfer (other than the relaxase) were detected. These plasmids proved to have a great plasticity at using a wide variety of conjugative apparatuses. The promiscuous recognition of non-cognate oriT sequences and the role of replication origins for lagging-strand origin in the host range of these plasmids are also discussed.
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria and Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Centro de Investigaciones Biomédicas de Canarias, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.
| | - Cris Fernández-López
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, E-28040 Madrid, Spain.
| | - M Pilar Garcillán-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria - CSIC-SODERCAN, Santander, Cantabria, Spain.
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, E-28040 Madrid, Spain.
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13
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Abstract
Secretion of effectors across bacterial membranes is usually mediated by large multisubunit complexes. In most cases, the secreted effectors are virulent factors normally associated to pathogenic diseases. The biogenesis of these secretion systems and the transport of the effectors are processes that require energy. This energy could be directly obtained by using the proton motive force, but in most cases the energy associated to these processes is derived from ATP hydrolysis. Here, a description of the machineries involved in generating the energy required for system biogenesis and substrate transport by type II, III and IV secretion systems is provided, with special emphasis on highlighting the structural similarities and evolutionary relationships among the secretion ATPases.
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Affiliation(s)
- Alejandro Peña
- Departamento de Biología Molecular, Universidad de Cantabria, UC-CSIC-SODERCAN, Santander, Spain
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14
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Fernández-López C, Lorenzo-Díaz F, Pérez-Luque R, Rodríguez-González L, Boer R, Lurz R, Bravo A, Coll M, Espinosa M. Nicking activity of the pMV158 MobM relaxase on cognate and heterologous origins of transfer. Plasmid 2013; 70:120-30. [DOI: 10.1016/j.plasmid.2013.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 10/27/2022]
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15
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van Wolferen M, Ajon M, Driessen AJM, Albers SV. How hyperthermophiles adapt to change their lives: DNA exchange in extreme conditions. Extremophiles 2013; 17:545-63. [PMID: 23712907 DOI: 10.1007/s00792-013-0552-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/12/2013] [Indexed: 01/24/2023]
Abstract
Transfer of DNA has been shown to be involved in genome evolution. In particular with respect to the adaptation of bacterial species to high temperatures, DNA transfer between the domains of bacteria and archaea seems to have played a major role. In addition, DNA exchange between similar species likely plays a role in repair of DNA via homologous recombination, a process that is crucial under DNA damaging conditions such as high temperatures. Several mechanisms for the transfer of DNA have been described in prokaryotes, emphasizing its general importance. However, until recently, not much was known about this process in prokaryotes growing in highly thermophilic environments. This review describes the different mechanisms of DNA transfer in hyperthermophiles, and how this may contribute to the survival and adaptation of hyperthermophilic archaea and bacteria to extreme environments.
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Affiliation(s)
- Marleen van Wolferen
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043 Marburg, Germany
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16
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Functional properties and structural requirements of the plasmid pMV158-encoded MobM relaxase domain. J Bacteriol 2013; 195:3000-8. [PMID: 23625844 DOI: 10.1128/jb.02264-12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A crucial element in the horizontal transfer of mobilizable and conjugative plasmids is the relaxase, a single-stranded endonuclease that nicks the origin of transfer (oriT) of the plasmid DNA. The relaxase of the pMV158 mobilizable plasmid is MobM (494 residues). In solution, MobM forms a dimer through its C-terminal domain, which is proposed to anchor the protein to the cell membrane and to participate in type 4 secretion system (T4SS) protein-protein interactions. In order to gain a deeper insight into the structural MobM requirements for efficient DNA catalysis, we studied two endonuclease domain variants that include the first 199 or 243 amino acid residues (MobMN199 and MobMN243, respectively). Our results confirmed that the two proteins behaved as monomers in solution. Interestingly, MobMN243 relaxed supercoiled DNA and cleaved single-stranded oligonucleotides harboring oriTpMV158, whereas MobMN199 was active only on supercoiled DNA. Protein stability studies using gel electrophoresis and mass spectrometry showed increased susceptibility to degradation at the domain boundary between the N- and C-terminal domains, suggesting that the domains change their relative orientation upon DNA binding. Overall, these results demonstrate that MobMN243 is capable of nicking the DNA substrate independently of its topology and that the amino acids 200 to 243 modulate substrate specificity but not the nicking activity per se. These findings suggest that these amino acids are involved in positioning the DNA for the nuclease reaction rather than in the nicking mechanism itself.
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17
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Guo W, Hao H, Dai M, Wang Y, Huang L, Peng D, Wang X, Wang H, Yao M, Sun Y, Liu Z, Yuan Z. Development of quinoxaline 1, 4-dioxides resistance in Escherichia coli and molecular change under resistance selection. PLoS One 2012; 7:e43322. [PMID: 22952665 PMCID: PMC3429478 DOI: 10.1371/journal.pone.0043322] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 07/19/2012] [Indexed: 11/24/2022] Open
Abstract
Quinoxaline 1, 4-dioxides (QdNOs) has been used in animals as antimicrobial agents and growth promoters for decades. However, the resistance to QdNOs in pathogenic bacteria raises worldwide concern but it is barely known. To explore the molecular mechanism involved in development of QdNOs resistance in Escherichia coli, 6 strains selected by QdNOs in vitro and 21 strains isolated from QdNOs-used swine farm were subjected to MIC determination and PCR amplification of oqxA gene. A conjugative transfer was carried out to evaluate the transfer risk of QdNOs resistant determinant. Furthermore, the transcriptional profile of a QdNOs-resistant E. coli (79O4-2) selected in vitro with its parent strain 79–161 was assayed with a prokaryotic suppression subtractive hybridization (SSH) PCR cDNA subtraction. The result showed that more than 95% (20/21) clinical isolates were oqxA positive, while all the 6 induced QdNOs-resistant strains carried no oqxA gene and exhibited low frequency of conjugation. 44 fragments were identified by SSH PCR subtraction in the QdNOs-resistant strain 79O4-2. 18 cDNAs were involved in biosynthesis of Fe-S cluster (narH), protein (rpoA, trmD, truA, glyS, ileS, rplFCX, rpsH, fusA), lipoate (lipA), lipid A (lpxC), trehalose (otsA), CTP(pyrG) and others molecular. The 11 cDNAs were related to metabolism or degradation of glycolysis (gpmA and pgi) and proteins (clpX, clpA, pepN and fkpB). The atpADG and ubiB genes were associated with ATP biosynthesis and electron transport chain. The pathway of the functional genes revealed that E. coli may adapt the stress generated by QdNOs or develop specific QdNOs-resistance by activation of antioxidative agents biosynthesis (lipoate and trehalose), protein biosynthesis, glycolysis and oxidative phosphorylation. This study initially reveals the possible molecular mechanism involved in the development of QdNOs-resistance in E. coli, providing with novel insights in prediction and assessment of the emergency and horizontal transfer of QdNOs-resistance in E. coli.
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Affiliation(s)
- Wentao Guo
- National Reference Laboratory of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China
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18
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Human mitochondrial transcription factor A induces a U-turn structure in the light strand promoter. Nat Struct Mol Biol 2011; 18:1281-9. [PMID: 22037172 DOI: 10.1038/nsmb.2160] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/13/2011] [Indexed: 11/09/2022]
Abstract
Human mitochondrial transcription factor A, TFAM, is essential for mitochondrial DNA packaging and maintenance and also has a crucial role in transcription. Crystallographic analysis of TFAM in complex with an oligonucleotide containing the mitochondrial light strand promoter (LSP) revealed two high-mobility group (HMG) protein domains that, through different DNA recognition properties, intercalate residues at two inverted DNA motifs. This induced an overall DNA bend of ~180°, stabilized by the interdomain linker. This U-turn allows the TFAM C-terminal tail, which recruits the transcription machinery, to approach the initiation site, despite contacting a distant DNA sequence. We also ascertained that structured protein regions contacting DNA in the crystal were highly flexible in solution in the absence of DNA. Our data suggest that TFAM bends LSP to create an optimal DNA arrangement for transcriptional initiation while facilitating DNA compaction elsewhere in the genome.
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19
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Cheng Y, McNamara DE, Miley MJ, Nash RP, Redinbo MR. Functional characterization of the multidomain F plasmid TraI relaxase-helicase. J Biol Chem 2011; 286:12670-82. [PMID: 21288910 PMCID: PMC3069467 DOI: 10.1074/jbc.m110.207563] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 01/25/2011] [Indexed: 11/06/2022] Open
Abstract
TraI, a bifunctional enzyme containing relaxase and helicase activities, initiates and drives the conjugative transfer of the Escherichia coli F plasmid. Here, we examined the structure and function of the TraI helicase. We show that TraI binds to single-stranded DNA (ssDNA) with a site size of ∼25 nucleotides, which is significantly longer than the site size of other known superfamily I helicases. Low cooperativity was observed with the binding of TraI to ssDNA, and a double-stranded DNA-binding site was identified within the N-terminal region of TraI 1-858, outside the core helicase motifs of TraI. We have revealed that the affinity of TraI for DNA is negatively correlated with the ionic strength of the solution. The binding of AMPPNP or ADP results in a 3-fold increase in the affinity of TraI for ssDNA. Moreover, TraI prefers to bind ssDNA oligomers containing a single type of base. Finally, we elucidated the solution structure of TraI using small angle x-ray scattering. TraI exhibits an ellipsoidal shape in solution with four domains aligning along one axis. Taken together, these data result in the assembly of a model for the multidomain helicase activity of TraI.
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Affiliation(s)
- Yuan Cheng
- From the Departments of Biochemistry and Biophysics and
- Program in Molecular and Cellular Biophysics, and
| | | | | | | | - Matthew R. Redinbo
- From the Departments of Biochemistry and Biophysics and
- Chemistry
- Program in Molecular and Cellular Biophysics, and
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599
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20
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Atassi MZ, Dolimbek BZ, Jankovic J, Steward LE, Aoki KR. Regions of botulinum neurotoxin A light chain recognized by human anti-toxin antibodies from cervical dystonia patients immunoresistant to toxin treatment. The antigenic structure of the active toxin recognized by human antibodies. Immunobiology 2010; 216:782-92. [PMID: 21281977 DOI: 10.1016/j.imbio.2010.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 12/15/2010] [Accepted: 12/19/2010] [Indexed: 11/16/2022]
Abstract
This work was aimed at determining the BoNT/A L-chain antigenic regions recognized by blocking antibodies in human antisera from cervical dystonia patients who had become immunoresistant to BoNT/A treatment. Antisera from 28 immunoresistant patients were analyzed for binding to each of 32 overlapping synthetic peptides that spanned the entire L-chain. A mixture of the antisera showed that antibodies bound to three peptides, L11 (residues 141-159), L14 (183-201) and L18 (239-257). When mapped separately, the antibodies were bound only by a limited set of peptides. No peptide bound antibodies from all the patients and amounts of antibodies bound to a given peptide varied with the patient. Peptides L11, L14 and L18 were recognized predominantly. A small but significant number of patients had antibodies to peptides L27 (365-383) and L29 (379-397). Other peptides were recognized at very low and perhaps insignificant antibody levels by a minority (15% or less) of patients or had no detectable antibody with any of the sera. In the 3-dimensional structure, antibody-binding regions L11, L14 and L18 of the L-chain occupy surface areas and did not correlate with electrostatic potential, hydrophilicity/hydrophobicity, or temperature factor. These three antigenic regions reside in close proximity to the belt of the heavy chain. The regions L11 and L18 are accessible in both the free light chain and the holotoxin forms, while L14 appears to be less accessible in the holotoxin. Antibodies against these regions could prevent delivery of the L-chain into the neurons by inhibition of the translocation.
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Affiliation(s)
- M Zouhair Atassi
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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21
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Abstract
Nucleases cleave the phosphodiester bonds of nucleic acids and may be endo or exo, DNase or RNase, topoisomerases, recombinases, ribozymes, or RNA splicing enzymes. In this review, I survey nuclease activities with known structures and catalytic machinery and classify them by reaction mechanism and metal-ion dependence and by their biological function ranging from DNA replication, recombination, repair, RNA maturation, processing, interference, to defense, nutrient regeneration or cell death. Several general principles emerge from this analysis. There is little correlation between catalytic mechanism and biological function. A single catalytic mechanism can be adapted in a variety of reactions and biological pathways. Conversely, a single biological process can often be accomplished by multiple tertiary and quaternary folds and by more than one catalytic mechanism. Two-metal-ion-dependent nucleases comprise the largest number of different tertiary folds and mediate the most diverse set of biological functions. Metal-ion-dependent cleavage is exclusively associated with exonucleases producing mononucleotides and endonucleases that cleave double- or single-stranded substrates in helical and base-stacked conformations. All metal-ion-independent RNases generate 2',3'-cyclic phosphate products, and all metal-ion-independent DNases form phospho-protein intermediates. I also find several previously unnoted relationships between different nucleases and shared catalytic configurations.
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22
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Abstract
DNA pumps play important roles in bacteria during cell division and during the transfer of genetic material by conjugation and transformation. The FtsK/SpoIIIE proteins carry out the translocation of double-stranded DNA to ensure complete chromosome segregation during cell division. In contrast, the complex molecular machines that mediate conjugation and genetic transformation drive the transport of single stranded DNA. The transformation machine also processes this internalized DNA and mediates its recombination with the resident chromosome during and after uptake, whereas the conjugation apparatus processes DNA before transfer. This article reviews these three types of DNA pumps, with attention to what is understood of their molecular mechanisms, their energetics and their cellular localizations.
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Affiliation(s)
- Briana Burton
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
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23
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Paauw A, Leverstein-van Hall MA, Verhoef J, Fluit AC. Evolution in quantum leaps: multiple combinatorial transfers of HPI and other genetic modules in Enterobacteriaceae. PLoS One 2010; 5:e8662. [PMID: 20084283 PMCID: PMC2801613 DOI: 10.1371/journal.pone.0008662] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 12/09/2009] [Indexed: 11/19/2022] Open
Abstract
Horizontal gene transfer is a key step in the evolution of Enterobacteriaceae. By acquiring virulence determinants of foreign origin, commensals can evolve into pathogens. In Enterobacteriaceae, horizontal transfer of these virulence determinants is largely dependent on transfer by plasmids, phages, genomic islands (GIs) and genomic modules (GMs). The High Pathogenicity Island (HPI) is a GI encoding virulence genes that can be transferred between different Enterobacteriaceae. We investigated the HPI because it was present in an Enterobacter hormaechei outbreak strain (EHOS). Genome sequence analysis showed that the EHOS contained an integration site for mobile elements and harbored two GIs and three putative GMs, including a new variant of the HPI (HPI-ICEEh1). We demonstrate, for the first time, that combinatorial transfers of GIs and GMs between Enterobacter cloacae complex isolates must have occurred. Furthermore, the excision and circularization of several combinations of the GIs and GMs was demonstrated. Because of its flexibility, the multiple integration site of mobile DNA can be considered an integration hotspot (IHS) that increases the genomic plasticity of the bacterium. Multiple combinatorial transfers of diverse combinations of the HPI and other genomic elements among Enterobacteriaceae may accelerate the generation of new pathogenic strains.
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Affiliation(s)
- Armand Paauw
- Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
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24
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Chandran V, Fronzes R, Duquerroy S, Cronin N, Navaza J, Waksman G. Structure of the outer membrane complex of a type IV secretion system. Nature 2009; 462:1011-5. [PMID: 19946264 PMCID: PMC2797999 DOI: 10.1038/nature08588] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Accepted: 10/19/2009] [Indexed: 02/07/2023]
Abstract
Type IV secretion systems are secretion nanomachines spanning the two membranes of Gram-negative bacteria. Three proteins, VirB7, VirB9 and VirB10, assemble into a 1.05 megadalton (MDa) core spanning the inner and outer membranes. This core consists of 14 copies of each of the proteins and forms two layers, the I and O layers, inserting in the inner and outer membrane, respectively. Here we present the crystal structure of a approximately 0.6 MDa outer-membrane complex containing the entire O layer. This structure is the largest determined for an outer-membrane channel and is unprecedented in being composed of three proteins. Unexpectedly, this structure identifies VirB10 as the outer-membrane channel with a unique hydrophobic double-helical transmembrane region. This structure establishes VirB10 as the only known protein crossing both membranes of Gram-negative bacteria. Comparison of the cryo-electron microscopy (cryo-EM) and crystallographic structures points to conformational changes regulating channel opening and closing.
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Affiliation(s)
- Vidya Chandran
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
| | - Rémi Fronzes
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
| | - Stéphane Duquerroy
- Institut Pasteur, Unité de Virologie Structurale, Virology Department and CNRS URA 3015, Paris, France
| | - Nora Cronin
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
| | - Jorge Navaza
- Laboratoire de Microscopie Electronique, Institut de Biologie Structurale J.P. Ebel, 41 rue Jules Horowitz, F-38027 Grenoble Cedex 1, France
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
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25
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Garriss G, Waldor MK, Burrus V. Mobile antibiotic resistance encoding elements promote their own diversity. PLoS Genet 2009; 5:e1000775. [PMID: 20019796 PMCID: PMC2786100 DOI: 10.1371/journal.pgen.1000775] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 11/16/2009] [Indexed: 12/27/2022] Open
Abstract
Integrating conjugative elements (ICEs) are a class of bacterial mobile genetic elements that disseminate via conjugation and then integrate into the host cell genome. The SXT/R391 family of ICEs consists of more than 30 different elements that all share the same integration site in the host chromosome but often encode distinct properties. These elements contribute to the spread of antibiotic resistance genes in several gram-negative bacteria including Vibrio cholerae, the agent of cholera. Here, using comparative analyses of the genomes of several SXT/R391 ICEs, we found evidence that the genomes of these elements have been shaped by inter–ICE recombination. We developed a high throughput semi-quantitative method to explore the genetic determinants involved in hybrid ICE formation. Recombinant ICE formation proved to be relatively frequent, and to depend on host (recA) and ICE (s065 and s066) loci, which can independently and potentially cooperatively mediate hybrid ICE formation. s065 and s066, which are found in all SXT/R391 ICEs, are orthologues of the bacteriophage λ Red recombination genes bet and exo, and the s065/s066 recombination system is the first Red-like recombination pathway to be described in a conjugative element. Neither ICE excision nor conjugative transfer proved to be essential for generation of hybrid ICEs. Instead conjugation facilitates the segregation of hybrids and could provide a means to select for functional recombinant ICEs containing novel combinations of genes conferring resistance to antibiotics. Thus, ICEs promote their own diversity and can yield novel mobile elements capable of disseminating new combinations of antibiotic resistance genes. Integrating and conjugative elements (ICEs) are a class of mobile elements found in diverse bacteria. ICEs of the SXT/R391 family have enabled the dissemination of genes conferring resistance to antibiotics among several important pathogens, including Vibrio cholerae, the agent of cholera. Here, using comparative analyses of the genomes of several SXT/R391 ICEs, we found that these elements are mosaics that have been shaped by inter–ICE recombination. We developed a plate-based method for semi-quantitative analyses of the genetic requirements for hybrid ICE formation. We discovered that hybrids form at relatively high frequencies and that both host and ICE genes can function independently and potentially cooperatively to mediate hybrid formation. The ICE–encoded recombination genes, which are found in all SXT/R391 ICEs, are related to genes that mediate recombination in bacteriophages, but have not been described previously in conjugative elements. Conjugative ICE transfer was not required for hybrid ICE formation but facilitates the segregation of hybrids. Thus, ICEs promote their own diversity and the generation of recombinant ICEs can yield novel mobile elements capable of disseminating new combinations of antibiotic resistance genes.
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Affiliation(s)
- Geneviève Garriss
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Matthew K. Waldor
- Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston, Massachusetts, United States of America
- * E-mail: (MKW); (VB)
| | - Vincent Burrus
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail: (MKW); (VB)
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26
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Alvarez-Martinez CE, Christie PJ. Biological diversity of prokaryotic type IV secretion systems. Microbiol Mol Biol Rev 2009; 73:775-808. [PMID: 19946141 PMCID: PMC2786583 DOI: 10.1128/mmbr.00023-09] [Citation(s) in RCA: 524] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Type IV secretion systems (T4SS) translocate DNA and protein substrates across prokaryotic cell envelopes generally by a mechanism requiring direct contact with a target cell. Three types of T4SS have been described: (i) conjugation systems, operationally defined as machines that translocate DNA substrates intercellularly by a contact-dependent process; (ii) effector translocator systems, functioning to deliver proteins or other macromolecules to eukaryotic target cells; and (iii) DNA release/uptake systems, which translocate DNA to or from the extracellular milieu. Studies of a few paradigmatic systems, notably the conjugation systems of plasmids F, R388, RP4, and pKM101 and the Agrobacterium tumefaciens VirB/VirD4 system, have supplied important insights into the structure, function, and mechanism of action of type IV secretion machines. Information on these systems is updated, with emphasis on recent exciting structural advances. An underappreciated feature of T4SS, most notably of the conjugation subfamily, is that they are widely distributed among many species of gram-negative and -positive bacteria, wall-less bacteria, and the Archaea. Conjugation-mediated lateral gene transfer has shaped the genomes of most if not all prokaryotes over evolutionary time and also contributed in the short term to the dissemination of antibiotic resistance and other virulence traits among medically important pathogens. How have these machines adapted to function across envelopes of distantly related microorganisms? A survey of T4SS functioning in phylogenetically diverse species highlights the biological complexity of these translocation systems and identifies common mechanistic themes as well as novel adaptations for specialized purposes relating to the modulation of the donor-target cell interaction.
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Affiliation(s)
- Cristina E. Alvarez-Martinez
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin, Houston, Texas 77030
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin, Houston, Texas 77030
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27
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Boer DR, Ruíz-Masó JA, López-Blanco JR, Blanco AG, Vives-Llàcer M, Chacón P, Usón I, Gomis-Rüth FX, Espinosa M, Llorca O, del Solar G, Coll M. Plasmid replication initiator RepB forms a hexamer reminiscent of ring helicases and has mobile nuclease domains. EMBO J 2009; 28:1666-78. [PMID: 19440202 DOI: 10.1038/emboj.2009.125] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 04/07/2009] [Indexed: 11/09/2022] Open
Abstract
RepB initiates plasmid rolling-circle replication by binding to a triple 11-bp direct repeat (bind locus) and cleaving the DNA at a specific distant site located in a hairpin loop within the nic locus of the origin. The structure of native full-length RepB reveals a hexameric ring molecule, where each protomer has two domains. The origin-binding and catalytic domains show a three-layer alpha-beta-alpha sandwich fold. The active site is positioned at one of the faces of the beta-sheet and coordinates a Mn2+ ion at short distance from the essential nucleophilic Y99. The oligomerization domains (ODs), each consisting of four alpha-helices, together define a compact ring with a central channel, a feature found in ring helicases. The toroidal arrangement of RepB suggests that, similar to ring helicases, it encircles one of the DNA strands during replication to confer processivity to the replisome complex. The catalytic domains appear to be highly mobile with respect to ODs. This mobility may account for the adaptation of the protein to two distinct DNA recognition sites.
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Affiliation(s)
- D Roeland Boer
- Institute for Research in Biomedicine, Barcelona Science Park, Barcelona, Spain
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Abstract
Conjugation, mobilization, and retromobilization are three related mechanisms of horizontal gene transfer in bacteria. They have been extensively studied in gram-negative species, where retromobilization, the capture of DNA from a recipient by a donor cell, was shown to result from two successive steps: the transfer of the conjugative plasmid from the donor to the recipient followed by the retrotransfer of the mobilizable plasmid to the donor. This successive model was established for gram-negative bacteria but was lacking experimental data from the gram-positive counterparts. In the present work, the mobilization and retromobilization abilities of the conjugative plasmid pXO16 from Bacillus thuringiensis subsp. israelensis were studied using the mobilizable plasmids pUB110 and pE194 and the "nonmobilizable" element pC194 lacking the mob and oriT features (all from Staphylococcus aureus). Experimental data suggested a successive model, since different retromobilization frequencies were observed between the small plasmids. More importantly, retromobilization was shown to be delayed by 50 and 150 min for pUB110 and pE194, respectively, compared to pXO16 conjugation. Natural liquid foods (cow milk, soy milk, and rice milk) were used to evaluate the putative ecological impact of these transfers. In cow and soy milk, conjugation, mobilization, and retromobilization were shown to occur at frequencies of 8.0 x 10(-1), 1.0 x 10(-2), and 1.2 x 10(-4) transconjugants per recipient, respectively. These data are comparable to those obtained with LB medium and about 10-fold lower than in the case of rice milk. Taken together, these results emphasize the potential role of plasmid capture played by B. thuringiensis in natural environments.
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An equivalent metal ion in one- and two-metal-ion catalysis. Nat Struct Mol Biol 2008; 15:1228-31. [PMID: 18953336 DOI: 10.1038/nsmb.1502] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Accepted: 09/24/2008] [Indexed: 11/08/2022]
Abstract
Nucleotidyl-transfer enzymes, which synthesize, degrade and rearrange DNA and RNA, often depend on metal ions for catalysis. All DNA and RNA polymerases, MutH-like or RNase H-like nucleases and recombinases, and group I introns seem to require two divalent cations to form a complete active site. The two-metal-ion mechanism has been proposed to orient the substrate, facilitate acid-base catalysis and allow catalytic specificity to exceed substrate binding specificity attributable to the stringent metal-ion (Mg2+ in particular) coordination. Not all nucleotidyl-transfer enzymes use two metal ions for catalysis, however. The betabetaalpha-Me and HUH nucleases depend on a single metal ion in the active site for the catalysis. All of these one- and two metal ion-dependent enzymes generate 5'-phosphate and 3'-OH products. Structural and mechanistic comparisons show that these seemingly unrelated nucleotidyl-transferases share a functionally equivalent metal ion.
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Lu J, Wong JJW, Edwards RA, Manchak J, Frost LS, Glover JNM. Structural basis of specific TraD-TraM recognition during F plasmid-mediated bacterial conjugation. Mol Microbiol 2008; 70:89-99. [PMID: 18717787 DOI: 10.1111/j.1365-2958.2008.06391.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
F plasmid-mediated bacterial conjugation requires interactions between a relaxosome component, TraM, and the coupling protein TraD, a hexameric ring ATPase that forms the cytoplasmic face of the conjugative pore. Here we present the crystal structure of the C-terminal tail of TraD bound to the TraM tetramerization domain, the first structural evidence of relaxosome-coupling protein interactions. The structure reveals the TraD C-terminal peptide bound to each of four symmetry-related grooves on the surface of the TraM tetramer. Extensive protein-protein interactions were observed between the two proteins. Mutational analysis indicates that these interactions are specific and required for efficient F conjugation in vivo. Our results suggest that specific interactions between the C-terminal tail of TraD and the TraM tetramerization domain might lead to more generalized interactions that stabilize the relaxosome-coupling protein complex in preparation for conjugative DNA transfer.
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Affiliation(s)
- Jun Lu
- Departments of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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31
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Grange W, Duckely M, Husale S, Jacob S, Engel A, Hegner M. VirE2: a unique ssDNA-compacting molecular machine. PLoS Biol 2008; 6:e44. [PMID: 18303950 PMCID: PMC2253637 DOI: 10.1371/journal.pbio.0060044] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 01/08/2008] [Indexed: 11/18/2022] Open
Abstract
The translocation of single-stranded DNA (ssDNA) across membranes of two cells is a fundamental biological process occurring in both bacterial conjugation and Agrobacterium pathogenesis. Whereas bacterial conjugation spreads antibiotic resistance, Agrobacterium facilitates efficient interkingdom transfer of ssDNA from its cytoplasm to the host plant cell nucleus. These processes rely on the Type IV secretion system (T4SS), an active multiprotein channel spanning the bacterial inner and outer membranes. T4SSs export specific proteins, among them relaxases, which covalently bind to the 5' end of the translocated ssDNA and mediate ssDNA export. In Agrobacterium tumefaciens, another exported protein-VirE2-enhances ssDNA transfer efficiency 2000-fold. VirE2 binds cooperatively to the transferred ssDNA (T-DNA) and forms a compact helical structure, mediating T-DNA import into the host cell nucleus. We demonstrated-using single-molecule techniques-that by cooperatively binding to ssDNA, VirE2 proteins act as a powerful molecular machine. VirE2 actively pulls ssDNA and is capable of working against 50-pN loads without the need for external energy sources. Combining biochemical and cell biology data, we suggest that, in vivo, VirE2 binding to ssDNA allows an efficient import and pulling of ssDNA into the host. These findings provide a new insight into the ssDNA translocation mechanism from the recipient cell perspective. Efficient translocation only relies on the presence of ssDNA binding proteins in the recipient cell that compacts ssDNA upon binding. This facilitated transfer could hence be a more general ssDNA import mechanism also occurring in bacterial conjugation and DNA uptake processes.
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Affiliation(s)
- Wilfried Grange
- Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin, Ireland
- National Centre of Competence in Research Nanoscale Science, Institute of Physics, Basel, Switzerland
| | - Myriam Duckely
- M. E. Müller Institute for Structural Biology, Basel, Switzerland
- Novartis AG, Basel, Switzerland
| | - Sudhir Husale
- National Centre of Competence in Research Nanoscale Science, Institute of Physics, Basel, Switzerland
- Rowland Institute at Harvard, Harvard University, Cambridge, Massachusetts, United States of America
| | - Susan Jacob
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Engel
- M. E. Müller Institute for Structural Biology, Basel, Switzerland
| | - Martin Hegner
- Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin, Ireland
- National Centre of Competence in Research Nanoscale Science, Institute of Physics, Basel, Switzerland
- * To whom correspondence should be addressed. E-mail:
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Identification andin silico characterisation of putative conjugative transfer genes onGeobacillus stearothermophilus plasmids. ANN MICROBIOL 2007. [DOI: 10.1007/bf03175081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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