1
|
Ortiz Charneco G, Kelleher P, Buivydas A, Dashko S, de Waal PP, van Peij NNME, Roberts RJ, Mahony J, van Sinderen D. Delineation of a lactococcal conjugation system reveals a restriction-modification evasion system. Microb Biotechnol 2023; 16:1250-1263. [PMID: 36942662 DOI: 10.1111/1751-7915.14221] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 03/23/2023] Open
Abstract
Plasmid pUC11B is a 49.3-kb plasmid harboured by the fermented meat isolate Lactococcus lactis subsp. lactis UC11. Among other features, pUC11B encodes a pMRC01-like conjugation system and tetracycline-resistance. In this study, we demonstrate that this plasmid can be conjugated at high frequencies to recipient strains. Mutational analysis of the 22 genes encompassing the presumed pUC11B conjugation cluster revealed the presence of several genes with essential conjugation functions, as well as a gene, trsR, encoding a putative transcriptional repressor of this conjugation cluster. Furthermore, plasmid pUC11B encodes an anti-restriction protein, TrsAR, which facilitates higher conjugation frequencies when pUC11B is transferred into recipient strains containing Type II or Type III RM systems. These findings demonstrate how RM mechanisms can be circumvented when they act as a biological barrier for conjugation events.
Collapse
Affiliation(s)
| | - Philip Kelleher
- School of Microbiology & APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Andrius Buivydas
- School of Microbiology & APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Sofia Dashko
- DSM Food and Beverage, Center for Food Innovation, Delft, The Netherlands
| | - Paul P de Waal
- DSM Food and Beverage, Center for Food Innovation, Delft, The Netherlands
| | | | | | - Jennifer Mahony
- School of Microbiology & APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Douwe van Sinderen
- School of Microbiology & APC Microbiome Ireland, University College Cork, Cork, Ireland
| |
Collapse
|
2
|
Couturier A, Virolle C, Goldlust K, Berne-Dedieu A, Reuter A, Nolivos S, Yamaichi Y, Bigot S, Lesterlin C. Real-time visualisation of the intracellular dynamics of conjugative plasmid transfer. Nat Commun 2023; 14:294. [PMID: 36653393 PMCID: PMC9849209 DOI: 10.1038/s41467-023-35978-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 01/11/2023] [Indexed: 01/19/2023] Open
Abstract
Conjugation is a contact-dependent mechanism for the transfer of plasmid DNA between bacterial cells, which contributes to the dissemination of antibiotic resistance. Here, we use live-cell microscopy to visualise the intracellular dynamics of conjugative transfer of F-plasmid in E. coli, in real time. We show that the transfer of plasmid in single-stranded form (ssDNA) and its subsequent conversion into double-stranded DNA (dsDNA) are fast and efficient processes that occur with specific timing and subcellular localisation. Notably, the ssDNA-to-dsDNA conversion determines the timing of plasmid-encoded protein production. The leading region that first enters the recipient cell carries single-stranded promoters that allow the early and transient synthesis of leading proteins immediately upon entry of the ssDNA plasmid. The subsequent conversion into dsDNA turns off leading gene expression, and activates the expression of other plasmid genes under the control of conventional double-stranded promoters. This molecular strategy allows for the timely production of factors sequentially involved in establishing, maintaining and disseminating the plasmid.
Collapse
Affiliation(s)
- Agathe Couturier
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Chloé Virolle
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Kelly Goldlust
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Annick Berne-Dedieu
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Audrey Reuter
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Sophie Nolivos
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Yoshiharu Yamaichi
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Sarah Bigot
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France.
| | - Christian Lesterlin
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France.
| |
Collapse
|
3
|
Juhas M. Gene Transfer. BRIEF LESSONS IN MICROBIOLOGY 2023:51-63. [DOI: 10.1007/978-3-031-29544-7_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
|
4
|
Nagy ED, Kuehn R, Wang D, Shrawat A, Duda DM, Groat JR, Yang P, Beach S, Zhang Y, Rymarquis L, Carter SL, Gaeta RT, Gilbertson LA. Site-directed integration of exogenous DNA into the soybean genome by LbCas12a fused to a plant viral HUH endonuclease. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:905-916. [PMID: 35635764 DOI: 10.1111/tpj.15849] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
High efficiency site-directed chromosomal integration of exogenous DNA in plants remains a challenge despite recent advances in genome editing technologies. One approach to mitigate this problem is to increase the effective concentration of the donor DNA at the target site of interest. HUH endonucleases (ENs) coordinate rolling circle replication. In vitro, they can form stable covalent bonds with DNA that carries their recognition motifs. When fused to a CRISPR-associated endonuclease, HUH ENs may improve integration rates by increasing the local donor concentration through tethering of the donor to the CRISPR nuclease. We tested this hypothesis by using chimeric proteins between LbCas12a as a CRISPR-associated endonuclease and the HUH EN from Faba Bean Necrotic Yellow Virus in soybean (Glycine max). Two fusion protein configurations were tested to integrate a 70-nt oligonucleotide donor into a commercially important target site using protoplasts and in planta transformation. Site-directed integration rates of the donor DNA, when tethered to the fusion protein, reached about 26% in plants and were up to four-fold higher than in untethered controls. Integrations via canonical homology-directed repair or non-homologous end joining were promoted by tethering in a similar fashion. This study is the first demonstration of HUH EN-associated tethering to improve site-directed DNA integration in plants.
Collapse
Affiliation(s)
| | | | - Dafu Wang
- Bayer Crop Science, St. Louis, Missouri, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Virolle C, Goldlust K, Djermoun S, Bigot S, Lesterlin C. Plasmid Transfer by Conjugation in Gram-Negative Bacteria: From the Cellular to the Community Level. Genes (Basel) 2020; 11:genes11111239. [PMID: 33105635 PMCID: PMC7690428 DOI: 10.3390/genes11111239] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/15/2020] [Accepted: 10/20/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial conjugation, also referred to as bacterial sex, is a major horizontal gene transfer mechanism through which DNA is transferred from a donor to a recipient bacterium by direct contact. Conjugation is universally conserved among bacteria and occurs in a wide range of environments (soil, plant surfaces, water, sewage, biofilms, and host-associated bacterial communities). Within these habitats, conjugation drives the rapid evolution and adaptation of bacterial strains by mediating the propagation of various metabolic properties, including symbiotic lifestyle, virulence, biofilm formation, resistance to heavy metals, and, most importantly, resistance to antibiotics. These properties make conjugation a fundamentally important process, and it is thus the focus of extensive study. Here, we review the key steps of plasmid transfer by conjugation in Gram-negative bacteria, by following the life cycle of the F factor during its transfer from the donor to the recipient cell. We also discuss our current knowledge of the extent and impact of conjugation within an environmentally and clinically relevant bacterial habitat, bacterial biofilms.
Collapse
|
6
|
Protein Dynamics in F-like Bacterial Conjugation. Biomedicines 2020; 8:biomedicines8090362. [PMID: 32961700 PMCID: PMC7555446 DOI: 10.3390/biomedicines8090362] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 01/21/2023] Open
Abstract
Efficient in silico development of novel antibiotics requires high-resolution, dynamic models of drug targets. As conjugation is considered the prominent contributor to the spread of antibiotic resistance genes, targeted drug design to disrupt vital components of conjugative systems has been proposed to lessen the proliferation of bacterial antibiotic resistance. Advancements in structural imaging techniques of large macromolecular complexes has accelerated the discovery of novel protein-protein interactions in bacterial type IV secretion systems (T4SS). The known structural information regarding the F-like T4SS components and complexes has been summarized in the following review, revealing a complex network of protein-protein interactions involving domains with varying degrees of disorder. Structural predictions were performed to provide insight on the dynamicity of proteins within the F plasmid conjugative system that lack structural information.
Collapse
|
7
|
Miyakoshi M, Ohtsubo Y, Nagata Y, Tsuda M. Transcriptome Analysis of Zygotic Induction During Conjugative Transfer of Plasmid RP4. Front Microbiol 2020; 11:1125. [PMID: 32625173 PMCID: PMC7314908 DOI: 10.3389/fmicb.2020.01125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/05/2020] [Indexed: 11/23/2022] Open
Abstract
Conjugative transfer of bacterial plasmid is one of the major mechanisms of horizontal gene transfer, which is mediated by direct contact between donor and recipient cells. Gene expression of a conjugative plasmid is tightly regulated mostly by plasmid-encoded transcriptional regulators, but it remains obscure how differently plasmid genes are expressed in each cell during the conjugation event. Here, we report a comprehensive analysis of gene expression during conjugative transfer of plasmid RP4, which is transferred between isogenic strains of Pseudomonas putida KT2440 at very high frequency. To discriminate the expression changes in the donor and recipient cells, we took advantage of conjugation in the presence of rifampicin (Rif). Within 10 min of mating, we successfully detected transient transcription of plasmid genes in the resultant transconjugant cells. This phenomenon known as zygotic induction is likely attributed to derepression of multiple RP4-encoded repressors. Interestingly, we also observed that the traJIH operon encoding relaxase and its auxiliary proteins were upregulated specifically in the donor cells. Identification of the 5′ end of the zygotically induced traJ mRNA confirmed that the transcription start site of traJ was located 24-nt upstream of the nick site in the origin of transfer (oriT) as previously reported. Since the traJ promoter is encoded on the region to be transferred first, the relaxase may be expressed in the donor cell after regeneration of the oriT-flanking region, which in itself is likely to displace the autogenous repressors around oriT. This study provides new insights into the regulation of plasmid transfer processes.
Collapse
Affiliation(s)
- Masatoshi Miyakoshi
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.,Division of Biomedical Science, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yoshiyuki Ohtsubo
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Yuji Nagata
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Masataka Tsuda
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| |
Collapse
|
8
|
Abushaheen MA, Muzaheed, Fatani AJ, Alosaimi M, Mansy W, George M, Acharya S, Rathod S, Divakar DD, Jhugroo C, Vellappally S, Khan AA, Shaik J, Jhugroo P. Antimicrobial resistance, mechanisms and its clinical significance. Dis Mon 2020; 66:100971. [PMID: 32201008 DOI: 10.1016/j.disamonth.2020.100971] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Antimicrobial agents play a key role in controlling and curing infectious disease. Soon after the discovery of the first antibiotic, the challenge of antibiotic resistance commenced. Antimicrobial agents use different mechanisms against bacteria to prevent their pathogenesis and they can be classified as bactericidal or bacteriostatic. Antibiotics are one of the antimicrobial agents which has several classes, each with different targets. Consequently, bacteria are endlessly using methods to overcome the effectivity of the antibiotics by using distinct types of mechanisms. Comprehending the mechanisms of resistance is vital for better understanding and to continue use of current antibiotics. Which also helps to formulate synthetic antimicrobials to overcome the current mechanism of resistance. Also, encourage in prudent use and misuse of antimicrobial agents. Thus, decline in treatment costs and in the rate of morbidity and mortality. This review will be concentrating on the mechanism of actions of several antibiotics and how bacteria develop resistance to them, as well as the method of acquiring the resistance in several bacteria and how can a strain be resistant to several types of antibiotics. This review also analyzes the prevalence, major clinical implications, clinical causes of antibiotic resistance. Further, it evaluates the global burden of antimicrobial resistance, identifies various challenges and strategies in addressing the issue. Finally, put forward certain recommendations to prevent the spread and reduce the rate of resistance growth.
Collapse
Affiliation(s)
- Manar Ali Abushaheen
- Department of Clinical Laboratory Science, College of Applied Medical Sciences, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Muzaheed
- Department of Clinical Laboratory Science, College of Applied Medical Sciences, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.
| | - Amal Jamil Fatani
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Mohammed Alosaimi
- Consultant, Department of Restorative Dentistry, College of Dentistry, King Saud bin Abdul Aziz University for Health Sciences, P.O Box: 22490, Riyadh 11426, Saudi Arabia
| | - Wael Mansy
- Clinical Pharmacy Department, College of Pharmacy, King Saud University, Saudi Arabia; Pharmacology Department, Faculty of Medicine, Cairo University, Egypt
| | - Merin George
- General Dentist and Public Health Researcher, Australia
| | - Sadananda Acharya
- Department of Public Health, College of Public Health, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Sanjay Rathod
- Department of Post Graduate Studies and Research in Microbiology, Gulbarga University, Gulbarga- 585106, India
| | - Darshan Devang Divakar
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Chitra Jhugroo
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Sajith Vellappally
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Aftab Ahmed Khan
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Jilani Shaik
- Genome Research Chair, Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Poojdev Jhugroo
- CAP Research Ltd., 2nd Floor Orbis Court, 132 St Jean Road 72218 Quatre Bornes, Mauritius
| |
Collapse
|
9
|
Heilers JH, Reiners J, Heller EM, Golzer A, Smits SHJ, van der Does C. DNA processing by the MOBH family relaxase TraI encoded within the gonococcal genetic island. Nucleic Acids Res 2019; 47:8136-8153. [PMID: 31276596 PMCID: PMC6736028 DOI: 10.1093/nar/gkz577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 06/18/2019] [Accepted: 06/26/2019] [Indexed: 11/26/2022] Open
Abstract
Relaxases of the MOBH family are often found on large plasmids, genetic islands and integrative conjugative elements. Many members of this family contain an N-terminal relaxase domain (TraI_2) followed by a disordered middle part and a C-terminal domain of unknown function (TraI_2_C). The TraI_2 domain contains two putative metal-binding motifs, an HD domain motif and an alternative 3H motif. TraI, encoded within the gonococcal genetic island of Neisseria gonorrhoeae, is the prototype of the MOBH family. SAXS experiments showed that TraI_2 and TraI_2_C form globular structures separated by an extended middle domain. The TraI_2 domain cleaves oriT-ssDNA in a site-specific Mn2+ or Co2+ dependent manner. The minimal oriT encompasses 50 nucleotides, requires an inverted repeat 3′ of the nic-site and several nucleotides around nic for efficient cleavage. Surprisingly, no stable covalent relaxase-DNA intermediate was observed. Mutagenesis of conserved tyrosines showed that cleavage was abolished in the Y212A mutant, whereas the Y212F and Y212H mutants retained residual activity. The HD and the alternative 3H motifs were essential for cleavage and the HD domain residues D162 and D267 for metal ion binding. We propose that the active site binds two metal ions, one in a high-affinity and one in a low-affinity site.
Collapse
Affiliation(s)
- Jan-Hendrik Heilers
- Institute for Biology II, Microbiology, Albert Ludwig University Freiburg, 79104 Freiburg, Germany
| | - Jens Reiners
- Biochemie I, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.,Center for Structural Studies, Heinrich Heine University, 40225 Düsseldorf, Germany
| | | | - Annika Golzer
- Institute for Biology II, Microbiology, Albert Ludwig University Freiburg, 79104 Freiburg, Germany
| | - Sander H J Smits
- Biochemie I, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.,Center for Structural Studies, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Chris van der Does
- Institute for Biology II, Microbiology, Albert Ludwig University Freiburg, 79104 Freiburg, Germany
| |
Collapse
|
10
|
Spread and Persistence of Virulence and Antibiotic Resistance Genes: A Ride on the F Plasmid Conjugation Module. EcoSal Plus 2019; 8. [PMID: 30022749 DOI: 10.1128/ecosalplus.esp-0003-2018] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The F plasmid or F-factor is a large, 100-kbp, circular conjugative plasmid of Escherichia coli and was originally described as a vector for horizontal gene transfer and gene recombination in the late 1940s. Since then, F and related F-like plasmids have served as role models for bacterial conjugation. At present, more than 200 different F-like plasmids with highly related DNA transfer genes, including those for the assembly of a type IV secretion apparatus, are completely sequenced. They belong to the phylogenetically related MOBF12A group. F-like plasmids are present in enterobacterial hosts isolated from clinical as well as environmental samples all over the world. As conjugative plasmids, F-like plasmids carry genetic modules enabling plasmid replication, stable maintenance, and DNA transfer. In this plasmid backbone of approximately 60 kbp, the DNA transfer genes occupy the largest and mostly conserved part. Subgroups of MOBF12A plasmids can be defined based on the similarity of TraJ, a protein required for DNA transfer gene expression. In addition, F-like plasmids harbor accessory cargo genes, frequently embedded within transposons and/or integrons, which harness their host bacteria with antibiotic resistance and virulence genes, causing increasingly severe problems for the treatment of infectious diseases. Here, I focus on key genetic elements and their encoded proteins present on the F-factor and other typical F-like plasmids belonging to the MOBF12A group of conjugative plasmids.
Collapse
|
11
|
Waksman G. From conjugation to T4S systems in Gram-negative bacteria: a mechanistic biology perspective. EMBO Rep 2019; 20:embr.201847012. [PMID: 30602585 PMCID: PMC6362355 DOI: 10.15252/embr.201847012] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/31/2018] [Accepted: 11/27/2018] [Indexed: 12/19/2022] Open
Abstract
Conjugation is the process by which bacteria exchange genetic materials in a unidirectional manner from a donor cell to a recipient cell. The discovery of conjugation signalled the dawn of genetics and molecular biology. In Gram-negative bacteria, the process of conjugation is mediated by a large membrane-embedded machinery termed "conjugative type IV secretion (T4S) system", a large injection nanomachine, which together with a DNA-processing machinery termed "the relaxosome" and a large extracellular tube termed "pilus" orchestrates directional DNA transfer. Here, the focus is on past and latest research in the field of conjugation and T4S systems in Gram-negative bacteria, with an emphasis on the various questions and debates that permeate the field from a mechanistic perspective.
Collapse
Affiliation(s)
- Gabriel Waksman
- Institute of Structural and Molecular Biology, UCL and Birkbeck, London, UK
| |
Collapse
|
12
|
Shala-Lawrence A, Bragagnolo N, Nowroozi-Dayeni R, Kheyson S, Audette GF. The interaction of TraW and TrbC is required to facilitate conjugation in F-like plasmids. Biochem Biophys Res Commun 2018; 503:2386-2392. [PMID: 29966652 DOI: 10.1016/j.bbrc.2018.06.166] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 06/28/2018] [Indexed: 12/20/2022]
Abstract
Bacterial conjugation, such as that mediated by the E. coli F plasmid, is a main mechanism driving bacterial evolution. Two important proteins required for F-pilus assembly and DNA transfer proficiency are TraW and TrbC. As members of a larger complex, these proteins assemble into a type IV secretion system and are essential components of pore formation and mating pair stabilization between the donor and the recipient cells. In the current report, we demonstrate the physical interaction of TraW and TrbC, show that TraW preferentially interacts with the N-terminal domain of TrbC, and that this interaction is important in restoring conjugation in traW/trbC knockouts.
Collapse
Affiliation(s)
- Agnesa Shala-Lawrence
- Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada
| | - Nicholas Bragagnolo
- Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada
| | - Roksana Nowroozi-Dayeni
- Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada
| | - Sasha Kheyson
- Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada
| | - Gerald F Audette
- Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada.
| |
Collapse
|
13
|
Rubio-Cosials A, Schulz EC, Lambertsen L, Smyshlyaev G, Rojas-Cordova C, Forslund K, Karaca E, Bebel A, Bork P, Barabas O. Transposase-DNA Complex Structures Reveal Mechanisms for Conjugative Transposition of Antibiotic Resistance. Cell 2018; 173:208-220.e20. [PMID: 29551265 PMCID: PMC5871717 DOI: 10.1016/j.cell.2018.02.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/08/2018] [Accepted: 02/12/2018] [Indexed: 12/28/2022]
Abstract
Conjugative transposition drives the emergence of multidrug resistance in diverse bacterial pathogens, yet the mechanisms are poorly characterized. The Tn1549 conjugative transposon propagates resistance to the antibiotic vancomycin used for severe drug-resistant infections. Here, we present four high-resolution structures of the conserved Y-transposase of Tn1549 complexed with circular transposon DNA intermediates. The structures reveal individual transposition steps and explain how specific DNA distortion and cleavage mechanisms enable DNA strand exchange with an absolute minimum homology requirement. This appears to uniquely allow Tn916-like conjugative transposons to bypass DNA homology and insert into diverse genomic sites, expanding gene transfer. We further uncover a structural regulatory mechanism that prevents premature cleavage of the transposon DNA before a suitable target DNA is found and generate a peptide antagonist that interferes with the transposase-DNA structure to block transposition. Our results reveal mechanistic principles of conjugative transposition that could help control the spread of antibiotic resistance genes. Antibiotic resistance-carrying conjugative transposon integrase structure revealed DNA distortion and special cleavage site allow insertion into diverse genomic sites Key structural features are conserved among numerous conjugative transposons Structures uncover auto-inhibition, allowing transposition antagonist design
Collapse
Affiliation(s)
- Anna Rubio-Cosials
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Eike C Schulz
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Hamburg Outstation, European Molecular Biology Laboratory, 22603 Hamburg, Germany
| | - Lotte Lambertsen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Georgy Smyshlyaev
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; European Bioinformatics Institute (EMBL-EBI), European Molecular Biology Laboratory, Hinxton CB10 1SD, UK
| | - Carlos Rojas-Cordova
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Kristoffer Forslund
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Ezgi Karaca
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Izmir Biomedicine and Genome Center (IBG), 35340 Izmir, Turkey
| | - Aleksandra Bebel
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Peer Bork
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; Molecular Medicine Partnership Unit, 69120 Heidelberg, Germany; Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Orsolya Barabas
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
| |
Collapse
|
14
|
Ilangovan A, Kay CWM, Roier S, El Mkami H, Salvadori E, Zechner EL, Zanetti G, Waksman G. Cryo-EM Structure of a Relaxase Reveals the Molecular Basis of DNA Unwinding during Bacterial Conjugation. Cell 2017; 169:708-721.e12. [PMID: 28457609 PMCID: PMC5422253 DOI: 10.1016/j.cell.2017.04.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 02/28/2017] [Accepted: 04/06/2017] [Indexed: 11/20/2022]
Abstract
Relaxases play essential roles in conjugation, the main process by which bacteria exchange genetic material, notably antibiotic resistance genes. They are bifunctional enzymes containing a trans-esterase activity, which is responsible for nicking the DNA strand to be transferred and for covalent attachment to the resulting 5'-phosphate end, and a helicase activity, which is responsible for unwinding the DNA while it is being transported to a recipient cell. Here we show that these two activities are carried out by two conformers that can both load simultaneously on the origin of transfer DNA. We solve the structure of one of these conformers by cryo electron microscopy to near-atomic resolution, elucidating the molecular basis of helicase function by relaxases and revealing insights into the mechanistic events taking place in the cell prior to substrate transport during conjugation.
Collapse
Affiliation(s)
- Aravindan Ilangovan
- Institute of Structural and Molecular Biology, Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Christopher W M Kay
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK; London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - Sandro Roier
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Hassane El Mkami
- School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Enrico Salvadori
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK; London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - Ellen L Zechner
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Giulia Zanetti
- Institute of Structural and Molecular Biology, Birkbeck, Malet Street, London WC1E 7HX, UK.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
| |
Collapse
|
15
|
Wisniewski JA, Rood JI. The Tcp conjugation system of Clostridium perfringens. Plasmid 2017; 91:28-36. [PMID: 28286218 DOI: 10.1016/j.plasmid.2017.03.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/24/2017] [Accepted: 03/06/2017] [Indexed: 11/18/2022]
Abstract
The Gram-positive pathogen Clostridium perfringens possesses a family of large conjugative plasmids that is typified by the tetracycline resistance plasmid pCW3. Since these plasmids may carry antibiotic resistance genes or genes encoding extracellular or sporulation-associated toxins, the conjugative transfer of these plasmids appears to be important for the epidemiology of C. perfringens-mediated diseases. Sequence analysis of members of this plasmid family identified a highly conserved 35kb region that encodes proteins with various functions, including plasmid replication and partitioning. The tcp conjugation locus also was identified in this region, initially based on low-level amino acid sequence identity to conjugation proteins from the integrative conjugative element Tn916. Genetic studies confirmed that the tcp locus is required for conjugative transfer and combined with biochemical and structural analyses have led to the development of a functional model of the Tcp conjugation apparatus. This review summarises our current understanding of the Tcp conjugation system, which is now one of the best-characterized conjugation systems in Gram-positive bacteria.
Collapse
Affiliation(s)
- Jessica A Wisniewski
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia
| | - Julian I Rood
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia.
| |
Collapse
|
16
|
Abstract
All plasmids that spread by conjugative transfer encode a relaxase. That includes plasmids that encode the type IV secretion machinery necessary to mediate cell to cell transfer, as well as mobilizable plasmids that exploit the existence of other plasmids' type IV secretion machinery to enable their own lateral spread. Relaxases perform key functions in plasmid transfer by first binding to their cognate plasmid as part of a multiprotein complex called the relaxosome, which is then specifically recognized by a receptor protein at the opening of the secretion channel. Relaxases catalyze a site- and DNA-strand-specific cleavage reaction on the plasmid then pilot the single strand of plasmid DNA through the membrane-spanning type IV secretion channel as a nucleoprotein complex. In the recipient cell, relaxases help terminate the transfer process efficiently and stabilize the incoming plasmid DNA. Here, we review the well-studied MOBF family of relaxases to describe the biochemistry of these versatile enzymes and integrate current knowledge into a mechanistic model of plasmid transfer in Gram-negative bacteria.
Collapse
|
17
|
Gruber CJ, Lang S, Rajendra VKH, Nuk M, Raffl S, Schildbach JF, Zechner EL. Conjugative DNA Transfer Is Enhanced by Plasmid R1 Partitioning Proteins. Front Mol Biosci 2016; 3:32. [PMID: 27486582 PMCID: PMC4949242 DOI: 10.3389/fmolb.2016.00032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 07/01/2016] [Indexed: 11/22/2022] Open
Abstract
Bacterial conjugation is a form of type IV secretion used to transport protein and DNA directly to recipient bacteria. The process is cell contact-dependent, yet the mechanisms enabling extracellular events to trigger plasmid transfer to begin inside the cell remain obscure. In this study of plasmid R1 we investigated the role of plasmid proteins in the initiation of gene transfer. We find that TraI, the central regulator of conjugative DNA processing, interacts physically, and functionally with the plasmid partitioning proteins ParM and ParR. These interactions stimulate TraI catalyzed relaxation of plasmid DNA in vivo and in vitro and increase ParM ATPase activity. ParM also binds the coupling protein TraD and VirB4-like channel ATPase TraC. Together, these protein-protein interactions probably act to co-localize the transfer components intracellularly and promote assembly of the conjugation machinery. Importantly these data also indicate that the continued association of ParM and ParR at the conjugative pore is necessary for plasmid transfer to start efficiently. Moreover, the conjugative pilus and underlying secretion machinery assembled in the absence of Par proteins mediate poor biofilm formation and are completely dysfunctional for pilus specific R17 bacteriophage uptake. Thus, functional integration of Par components at the interface of relaxosome, coupling protein, and channel ATPases appears important for an optimal conformation and effective activation of the transfer machinery. We conclude that low copy plasmid R1 has evolved an active segregation system that optimizes both its vertical and lateral modes of dissemination.
Collapse
Affiliation(s)
- Christian J Gruber
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Silvia Lang
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Vinod K H Rajendra
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Monika Nuk
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Sandra Raffl
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | | | - Ellen L Zechner
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| |
Collapse
|
18
|
Wisniewski JA, Traore DA, Bannam TL, Lyras D, Whisstock JC, Rood JI. TcpM: a novel relaxase that mediates transfer of large conjugative plasmids from Clostridium perfringens. Mol Microbiol 2015; 99:884-96. [PMID: 26560080 DOI: 10.1111/mmi.13270] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2015] [Indexed: 11/30/2022]
Abstract
Conjugative transfer of toxin and antibiotic resistance plasmids in Clostridium perfringens is mediated by the tcp conjugation locus. Surprisingly, neither a relaxase gene nor an origin of transfer (oriT) has been identified on these plasmids, which are typified by the 47 kb tetracycline resistance plasmid pCW3. The tcpM gene (previously called intP) encodes a potential tyrosine recombinase that was postulated to be an atypical relaxase. Mutagenesis and complementation studies showed that TcpM was required for wild-type transfer of pCW3 and that a tyrosine residue, Y259, was essential for TcpM activity, which was consistent with the need for a relaxase-mediated hydrophilic attack at the oriT site. Other catalytic residues conserved in tyrosine recombinases were not required for TcpM activity, suggesting that TcpM was not a site-specific recombinase. Mobilization studies led to the identification of the oriT site, which was located in the 391 bp intergenic region upstream of tcpM. The oriT site was localized to a 150 bp region, and gel mobility shift studies showed that TcpM could bind to this region. Based on these studies we postulate that conjugative transfer of pCW3 involves the atypical relaxase TcpM binding to and processing the oriT site to initiate plasmid transfer.
Collapse
Affiliation(s)
- Jessica A Wisniewski
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, and Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.,Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Daouda A Traore
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, and Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia
| | - Trudi L Bannam
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, and Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.,Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Dena Lyras
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, and Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.,Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - James C Whisstock
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, and Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia
| | - Julian I Rood
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, and Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.,Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| |
Collapse
|
19
|
Clark NJ, Raththagala M, Wright NT, Buenger EA, Schildbach JF, Krueger S, Curtis JE. Structures of TraI in solution. J Mol Model 2014; 20:2308. [PMID: 24898939 DOI: 10.1007/s00894-014-2308-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 05/12/2014] [Indexed: 10/25/2022]
Abstract
Bacterial conjugation, a DNA transfer mechanism involving transport of one plasmid strand from donor to recipient, is driven by plasmid-encoded proteins. The F TraI protein nicks one F plasmid strand, separates cut and uncut strands, and pilots the cut strand through a secretion pore into the recipient. TraI is a modular protein with identifiable nickase, ssDNA-binding, helicase and protein-protein interaction domains. While domain structures corresponding to roughly 1/3 of TraI have been determined, there has been no comprehensive structural study of the entire TraI molecule, nor an examination of structural changes to TraI upon binding DNA. Here, we combine solution studies using small-angle scattering and circular dichroism spectroscopy with molecular Monte Carlo and molecular dynamics simulations to assess solution behavior of individual and groups of domains. Despite having several long (>100 residues) apparently disordered or highly dynamic regions, TraI folds into a compact molecule. Based on the biophysical characterization, we have generated models of intact TraI. These data and the resulting models have provided clues to the regulation of TraI function.
Collapse
Affiliation(s)
- Nicholas J Clark
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD, 20899, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Common requirement for the relaxosome of plasmid R1 in multiple activities of the conjugative type IV secretion system. J Bacteriol 2014; 196:2108-21. [PMID: 24682328 DOI: 10.1128/jb.00045-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macromolecular transport by bacterial type IV secretion systems involves regulated uptake of (nucleo)protein complexes by the cell envelope-spanning transport channel. A coupling protein receptor is believed to recognize the specific proteins destined for transfer, but the steps initiating their translocation remain unknown. Here, we investigate the contribution of a complex of transfer initiation proteins, the relaxosome, of plasmid R1 to translocation of competing transferable substrates from mobilizable plasmids ColE1 and CloDF13 or the bacteriophage R17. We found that not only does the R1 translocation machinery engage the R1 relaxosome during conjugative self-transfer and during infection by R17 phage but it is also activated by its cognate relaxosome to mediate the export of an alternative plasmid. Transporter activity was optimized by the R1 relaxosome even when this complex itself could not be transferred, i.e., when the N-terminal activation domain (amino acids 1 to 992 [N1-992]) of TraI was present without the C-terminal conjugative helicase domain. We propose that the functional dependence of the transfer machinery on the R1 relaxosome for initiating translocation ensures that dissemination of heterologous plasmids does not occur at the expense of self-transfer.
Collapse
|
21
|
Catalytic domain of plasmid pAD1 relaxase TraX defines a group of relaxases related to restriction endonucleases. Proc Natl Acad Sci U S A 2013; 110:13606-11. [PMID: 23904483 DOI: 10.1073/pnas.1310037110] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plasmid pAD1 is a 60-kb conjugative element commonly found in clinical isolates of Enterococcus faecalis. The relaxase TraX and the primary origin of transfer oriT2 are located close to each other and have been shown to be essential for conjugation. The oriT2 site contains a large inverted repeat (where the nic site is located) adjacent to a series of short direct repeats. TraX does not show any of the typical relaxase sequence motifs but is the prototype of a unique family of relaxases (MOBC). The present study focuses on the genetic, biochemical, and structural analysis of TraX, whose 3D structure could be predicted by protein threading. The structure consists of two domains: (i) an N-terminal domain sharing the topology of the DNA binding domain of the MarR family of transcriptional regulators and (ii) a C-terminal catalytic domain related to the PD-(D/E)XK family of restriction endonucleases. Alignment of MOBC relaxase amino acid sequences pointed to several conserved polar amino acid residues (E28, D152, E170, E172, K176, R180, Y181, and Y203) that were mutated to alanine. Functional analysis of these mutants (in vivo DNA transfer and cleavage assays) revealed the importance of these residues for relaxase activity and suggests Y181 as a potential catalytic residue similarly to His-hydrophobe-His relaxases. We also show that TraX binds specifically to dsDNA containing the oriT2 direct repeat sequences, confirming their role in transfer specificity. The results provide insights into the catalytic mechanism of MOBC relaxases, which differs radically from that of His-hydrophobe-His relaxases.
Collapse
|
22
|
Abstract
Horizontal gene transfer has a tremendous impact on the genome plasticity, adaptation and evolution of bacteria. Horizontally transferred mobile genetic elements are involved in the dissemination of antibiotic resistance and virulence genes, thus contributing to the emergence of novel "superbugs". This review provides update on various mechanisms of horizontal gene transfer and examines how horizontal gene transfer contributes to the evolution of pathogenic bacteria. Special focus is paid to the role horizontal gene transfer plays in pathogenicity of the emerging human pathogens: hypervirulent Clostridium difficile and Escherichia coli (including the most recent haemolytic uraemic syndrome outbreak strain) and methicillin-resistant Staphylococcus aureus (MRSA), which have been associated with largest outbreaks of infection recently.
Collapse
Affiliation(s)
- Mario Juhas
- Department of Pathology, University of Cambridge , Cambridge , UK
| |
Collapse
|
23
|
Abstract
HUH endonucleases are numerous and widespread in all three domains of life. The major function of these enzymes is processing a range of mobile genetic elements by catalysing cleavage and rejoining of single-stranded DNA using an active-site Tyr residue to make a transient 5'-phosphotyrosine bond with the DNA substrate. These enzymes have a key role in rolling-circle replication of plasmids and bacteriophages, in plasmid transfer, in the replication of several eukaryotic viruses and in various types of transposition. They have also been appropriated for cellular processes such as intron homing and the processing of bacterial repeated extragenic palindromes. Here, we provide an overview of these fascinating enzymes and their functions, using well-characterized examples of Rep proteins, relaxases and transposases, and we explore the molecular mechanisms used in their diverse activities.
Collapse
|
24
|
Redzej A, Ilangovan A, Lang S, Gruber CJ, Topf M, Zangger K, Zechner EL, Waksman G. Structure of a translocation signal domain mediating conjugative transfer by type IV secretion systems. Mol Microbiol 2013; 89:324-33. [PMID: 23710762 PMCID: PMC3912908 DOI: 10.1111/mmi.12275] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2013] [Indexed: 01/26/2023]
Abstract
Relaxases are proteins responsible for the transfer of plasmid and chromosomal DNA from one bacterium to another during conjugation. They covalently react with a specific phosphodiester bond within DNA origin of transfer sequences, forming a nucleo-protein complex which is subsequently recruited for transport by a plasmid-encoded type IV secretion system. In previous work we identified the targeting translocation signals presented by the conjugative relaxase TraI of plasmid R1. Here we report the structure of TraI translocation signal TSA. In contrast to known translocation signals we show that TSA is an independent folding unit and thus forms a bona fide structural domain. This domain can be further divided into three subdomains with striking structural homology with helicase subdomains of the SF1B family. We also show that TSA is part of a larger vestigial helicase domain which has lost its helicase activity but not its single-stranded DNA binding capability. Finally, we further delineate the binding site responsible for translocation activity of TSA by targeting single residues for mutations. Overall, this study provides the first evidence that translocation signals can be part of larger structural scaffolds, overlapping with translocation-independent activities.
Collapse
Affiliation(s)
- Adam Redzej
- Institute of Structural and Molecular Biology, UCL and BirkbeckMalet Street, London, WC1E 7HX, UK
| | - Aravindan Ilangovan
- Institute of Structural and Molecular Biology, UCL and BirkbeckMalet Street, London, WC1E 7HX, UK
| | - Silvia Lang
- University of Graz, Institute of Molecular BiosciencesHumboldtstrasse 50, 8010, Graz, Austria
| | - Christian J Gruber
- University of Graz, Institute of Molecular BiosciencesHumboldtstrasse 50, 8010, Graz, Austria
| | - Maya Topf
- Institute of Structural and Molecular Biology, UCL and BirkbeckMalet Street, London, WC1E 7HX, UK
| | - Klaus Zangger
- University of Graz, Institute of ChemistryHeinrichstrasse 28, 8010, Graz, Austria
| | - Ellen L Zechner
- University of Graz, Institute of Molecular BiosciencesHumboldtstrasse 50, 8010, Graz, Austria
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, UCL and BirkbeckMalet Street, London, WC1E 7HX, UK
| |
Collapse
|
25
|
Hemmis CW, Schildbach JF. Thioredoxin-like proteins in F and other plasmid systems. Plasmid 2013; 70:168-89. [PMID: 23721857 DOI: 10.1016/j.plasmid.2013.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 05/12/2013] [Accepted: 05/13/2013] [Indexed: 11/29/2022]
Abstract
Bacterial conjugation is the process by which a conjugative plasmid transfers from donor to recipient bacterium. During this process, single-stranded plasmid DNA is actively and specifically transported from the cytoplasm of the donor, through a large membrane-spanning assembly known as the pore complex, and into the cytoplasm of the recipient. In Gram negative bacteria, construction of the pore requires localization of a subset of structural and catalytically active proteins to the bacterial periplasm. Unlike the cytoplasm, the periplasm contains proteins that promote disulfide bond formation within or between cysteine-containing proteins. To ensure proper protein folding and assembly, bacteria employ periplasmic redox systems for thiol oxidation, disulfide bond/sulfenic acid reduction, and disulfide bond isomerization. Recent data suggest that plasmid-based proteins belonging to the disulfide bond formation family play an integral role in the conjugative process by serving as mediators in folding and/or assembly of pore complex proteins. Here we report the identification of 165 thioredoxin-like family members across 89 different plasmid systems. Using phylogenetic analysis, all but nine family members were categorized into thioredoxin-like subfamilies. In addition, we discuss the diversity, conservation, and putative roles of thioredoxin-like proteins in plasmid systems, which include homologs of DsbA, DsbB, DsbC, DsbD, DsbG, and CcmG from Escherichia coli, TlpA from Bradyrhizobium japonicum, Com1 from Coxiella burnetii, as well as TrbB and TraF from plasmid F, and the absolute conservation of a disulfide isomerase in plasmids containing homologs of the transfer proteins TraH, TraN, and TraU.
Collapse
Affiliation(s)
- Casey W Hemmis
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | | |
Collapse
|
26
|
Becker EC, Meyer R. Origin and fate of the 3' ends of single-stranded DNA generated by conjugal transfer of plasmid R1162. J Bacteriol 2012; 194:5368-76. [PMID: 22865840 PMCID: PMC3457208 DOI: 10.1128/jb.00818-12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 07/24/2012] [Indexed: 11/20/2022] Open
Abstract
During conjugation, a single strand of DNA is cleaved at the origin of transfer (oriT) by the plasmid-encoded relaxase. This strand is then unwound from its complement and transferred in the 5'-to-3' direction, with the 3' end likely extended by rolling-circle replication. The resulting, newly synthesized oriT must then be cleaved as well, prior to recircularization of the strand in the recipient. Evidence is presented here that the R1162 relaxase contains only a single nucleophile capable of cleaving at oriT, with another molecule therefore required to cleave at a second site. An assay functionally isolating this second cleavage shows that this reaction can take place in the donor cell. As a result, there is a flux of strands with free 3' ends into the recipient. These ends are susceptible to degradation by exonuclease I. The degree of susceptibility is affected by the presence of an uncleaved oriT within the strand. A model is presented where these internal oriTs bind and trap the relaxase molecule covalently bound to the 5' end of the incoming strand. Such a mechanism would result in the preferential degradation of transferred DNA that had not been properly cleaved in the donor.
Collapse
Affiliation(s)
- Eric C Becker
- Section of Molecular Genetics and Microbiology, School of Biology and Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | | |
Collapse
|
27
|
Wong JJW, Lu J, Glover JNM. Relaxosome function and conjugation regulation in F-like plasmids - a structural biology perspective. Mol Microbiol 2012; 85:602-17. [PMID: 22788760 DOI: 10.1111/j.1365-2958.2012.08131.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The tra operon of the prototypical F plasmid and its relatives enables transfer of a copy of the plasmid to other bacterial cells via the process of conjugation. Tra proteins assemble to form the transferosome, the transmembrane pore through which the DNA is transferred, and the relaxosome, a complex of DNA-binding proteins at the origin of DNA transfer. F-like plasmid conjugation is characterized by a high degree of plasmid specificity in the interactions of tra components, and is tightly regulated at the transcriptional, translational and post-translational levels. Over the past decade, X-ray crystallography of conjugative components has yielded insights into both specificity and regulatory mechanisms. Conjugation is repressed by FinO, an RNA chaperone which increases the lifetime of the small RNA, FinP. Recent work has resulted in a detailed model of FinO/FinP interactions and the discovery of a family of FinO-like RNA chaperones. Relaxosome components include TraI, a relaxase/helicase, and TraM, which mediates signalling between the transferosome and relaxosome for transfer initiation. The structures of TraI and TraM bound to oriT DNA reveal the basis of specific recognition of DNA for their cognate plasmid. Specificity also exists in TraI and TraM interactions with the transferosome protein TraD.
Collapse
Affiliation(s)
- Joyce J W Wong
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | | | | |
Collapse
|
28
|
Wright NT, Raththagala M, Hemmis CW, Edwards S, Curtis JE, Krueger S, Schildbach JF. Solution structure and small angle scattering analysis of TraI (381-569). Proteins 2012; 80:2250-61. [PMID: 22611034 DOI: 10.1002/prot.24114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 04/15/2012] [Accepted: 05/02/2012] [Indexed: 12/12/2022]
Abstract
TraI, the F plasmid-encoded nickase, is a 1756 amino acid protein essential for conjugative transfer of plasmid DNA from one bacterium to another. Although crystal structures of N- and C-terminal domains of F TraI have been determined, central domains of the protein are structurally unexplored. The central region (between residues 306 and 1520) is known to both bind single-stranded DNA (ssDNA) and unwind DNA through a highly processive helicase activity. Here, we show that the ssDNA binding site is located between residues 381 and 858, and we also present the high-resolution solution structure of the N-terminus of this region (residues 381-569). This fragment folds into a four-strand parallel β sheet surrounded by α helices, and it resembles the structure of the N-terminus of helicases such as RecD and RecQ despite little sequence similarity. The structure supports the model that F TraI resulted from duplication of a RecD-like domain and subsequent specialization of domains into the more N-terminal ssDNA binding domain and the more C-terminal domain containing helicase motifs. In addition, we provide evidence that the nickase and ssDNA binding domains of TraI are held close together by an 80-residue linker sequence that connects the two domains. These results suggest a possible physical explanation for the apparent negative cooperativity between the nickase and ssDNA binding domain.
Collapse
Affiliation(s)
- Nathan T Wright
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | | | | | | | | | | | | |
Collapse
|
29
|
Lang S, Kirchberger PC, Gruber CJ, Redzej A, Raffl S, Zellnig G, Zangger K, Zechner EL. An activation domain of plasmid R1 TraI protein delineates stages of gene transfer initiation. Mol Microbiol 2011; 82:1071-85. [PMID: 22066957 PMCID: PMC3245843 DOI: 10.1111/j.1365-2958.2011.07872.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bacterial conjugation is a form of type IV secretion that transports protein and DNA to recipient cells. Specific bacteriophage exploit the conjugative pili and cell envelope spanning protein machinery of these systems to invade bacterial cells. Infection by phage R17 requires F-like pili and coupling protein TraD, which gates the cytoplasmic entrance of the secretion channel. Here we investigate the role of TraD in R17 nucleoprotein uptake and find parallels to secretion mechanisms. The relaxosome of IncFII plasmid R1 is required. A ternary complex of plasmid oriT, TraD and a novel activation domain within the N-terminal 992 residues of TraI contributes a key mechanism involving relaxase-associated properties of TraI, protein interaction and the TraD ATPase. Helicase-associated activities of TraI are dispensable. These findings distinguish for the first time specific protein domains and complexes that process extracellular signals into distinct activation stages in the type IV initiation pathway. The study also provided insights into the evolutionary interplay of phage and the plasmids they exploit. Related plasmid F adapted to R17 independently of TraI. It follows that selection for phage resistance drives not only variation in TraA pilins but diversifies TraD and its binding partners in a plasmid-specific manner.
Collapse
Affiliation(s)
- Silvia Lang
- University of Graz, Institute of Molecular Biosciences, Humboldtstrasse 50, 8010 Graz, Austria
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Nash RP, Niblock FC, Redinbo MR. Tyrosine partners coordinate DNA nicking by the Salmonella typhimurium plasmid pCU1 relaxase enzyme. FEBS Lett 2011; 585:1216-22. [PMID: 21439279 DOI: 10.1016/j.febslet.2011.03.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 03/17/2011] [Accepted: 03/18/2011] [Indexed: 10/18/2022]
Abstract
Conjugative plasmid transfer results in the spread of antibiotic resistance genes and virulence factors between bacterial cells. Plasmid transfer is dependent upon the DNA nicking activity of a plasmid-encoded relaxase enzyme. Tyrosine residues within the relaxase cleave the DNA plasmid nic site in a highly sequence-specific manner. The conjugative resistance plasmid pCU1 encodes a relaxase with four tyrosine residues surrounding its active site (Y18,19,26,27). We use activity assays to demonstrate that the pCU1 relaxase preferentially uses Y26 or a combination of Y18 + 19 to nick DNA at wild type levels, and that an adjacent aspartic acid deprotonates these tyrosines to activate them for attack. Our findings illustrate the unique modifications that the pCU1 relaxase has introduced into the traditional relaxase-mediated DNA nicking mechanism.
Collapse
Affiliation(s)
- Rebekah P Nash
- Department of Chemistry, Caudill and Kenan Laboratories, CB 3290, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA.
| | | | | |
Collapse
|