1
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Li YG, Breidenstein A, Berntsson RPA, Christie PJ. Conjugative transfer of the IncN plasmid pKM101 is mediated by dynamic interactions between the TraK accessory factor and TraI relaxase. FEBS Lett 2024. [PMID: 39245885 DOI: 10.1002/1873-3468.15011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 07/30/2024] [Accepted: 08/09/2024] [Indexed: 09/10/2024]
Abstract
Conjugative dissemination of mobile genetic elements (MGEs) among bacteria is initiated by assembly of the relaxosome at the MGE's origin-of-transfer (oriT) sequence. A critical but poorly defined step of relaxosome assembly involves recruitment of the catalytic relaxase to its DNA strand-specific nicking site within oriT. Here, we present evidence by AlphaFold modeling, affinity pulldowns, and in vivo site-directed photocrosslinking that the TraK Ribbon-Helix-Helix DNA-binding protein recruits TraI to oriT through a dynamic interaction in which TraI's C-terminal unstructured domain (TraICTD) wraps around TraK's C-proximal tetramerization domain. Upon relaxosome assembly, conformational changes disrupt this contact, and TraICTD instead self-associates as a prerequisite for relaxase catalytic functions or substrate engagement with the transfer channel. These findings delineate key early-stage processing reactions required for conjugative dissemination of a model MGE.
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Affiliation(s)
- Yang Grace Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, TX, USA
| | - Annika Breidenstein
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
- Wallenberg Centre for Molecular Medicine, Umeå Centre for Microbial Research, Umeå University, Sweden
| | - Ronnie P-A Berntsson
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
- Wallenberg Centre for Molecular Medicine, Umeå Centre for Microbial Research, Umeå University, Sweden
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, TX, USA
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2
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Zhou S, Zhao L, Zuo W, Zheng Y, Zhang P, Sun Y, Wang Y, Du G, Kang Z. Minimizing endogenous cryptic plasmids to construct antibiotic-free expression systems for Escherichia coli Nissle 1917. Synth Syst Biotechnol 2024; 9:165-175. [PMID: 38348398 PMCID: PMC10859263 DOI: 10.1016/j.synbio.2024.01.006] [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: 08/09/2023] [Revised: 12/25/2023] [Accepted: 01/11/2024] [Indexed: 02/15/2024] Open
Abstract
The probiotic bacterium Escherichia coli Nissle 1917 (EcN) holds significant promise for use in clinical and biological industries. However, the reliance on antibiotics to maintain plasmid-borne genes has overshadowed its benefits. In this study, we addressed this issue by engineering the endogenous cryptic plasmids pMUT1 and pMUT2. The non-essential elements were removed to create more stable derivatives pMUT1NR△ and pMUT2HBC△. Synthetic promoters by integrating binding motifs on sigma factors were further constructed and applied for expression of Bacteroides thetaiotaomicron heparinase III and the biosynthesis of ectoine. Compared to traditional antibiotic-dependent expression systems, our newly constructed antibiotic-free expression systems offer considerable advantages for clinical and synthetic biology applications.
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Affiliation(s)
- Siyan Zhou
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Linlin Zhao
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Wenjie Zuo
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Yilin Zheng
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Ping Zhang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Yanan Sun
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Yang Wang
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Guocheng Du
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Zhen Kang
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
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3
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Newberry F, Shibu P, Smith-Zaitlik T, Eladawy M, McCartney AL, Hoyles L, Negus D. Lytic bacteriophage vB_KmiS-Kmi2C disrupts biofilms formed by members of the Klebsiella oxytoca complex, and represents a novel virus family and genus. J Appl Microbiol 2023; 134:lxad079. [PMID: 37070958 DOI: 10.1093/jambio/lxad079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 04/05/2023] [Accepted: 04/14/2023] [Indexed: 04/19/2023]
Abstract
AIMS This study aimed to characterize the lytic phage vB_KmiS-Kmi2C, isolated from sewage water on a GES-positive strain of Klebsiella michiganensis. METHODS AND RESULTS Comparative phylogenetic and network-based analyses were used to characterize the genome of phage vB_KmiS-Kmi2C (circular genome of 42 234 bp predicted to encode 55 genes), demonstrating it shared little similarity with other known phages. The phage was lytic on clinical strains of K. oxytoca (n = 2) and K. michiganensis (n = 4), and was found to both prevent biofilm formation and disrupt established biofilms produced by these strains. CONCLUSIONS We have identified a phage capable of killing clinically relevant members of the K. oxytoca complex (KoC). The phage represents a novel virus family (proposed name Dilsviridae) and genus (proposed name Dilsvirus).
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Affiliation(s)
- Fiona Newberry
- Department of Biosciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - Preetha Shibu
- Life Sciences, University of Westminster, W1W 6UW, UK
| | - Thomas Smith-Zaitlik
- Department of Biosciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - Mohamed Eladawy
- Department of Biosciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
- Microbiology and Immunology Department, Faculty of Pharmacy, Mansoura University, Egypt
| | - Anne L McCartney
- Department of Biosciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - Lesley Hoyles
- Department of Biosciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - David Negus
- Department of Biosciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
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4
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Oliva M, Calia C, Ferrara M, D'Addabbo P, Scrascia M, Mulè G, Monno R, Pazzani C. Antimicrobial resistance gene shuffling and a three-element mobilisation system in the monophasic Salmonella typhimurium strain ST1030. Plasmid 2020; 111:102532. [PMID: 32853586 DOI: 10.1016/j.plasmid.2020.102532] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 11/30/2022]
Abstract
In this study we describe the genetic elements and the antimicrobial resistance units (RUs) harboured by the Salmonella Typhimurium monophasic variant 1,4,[5],12:i:- strain ST1030. Of the three identified RUs two were chromosomal, RU1 (IS26-blaTEM-1-IS26-strAB-sul2- IS26) and RU2 (IS26-tetR(B)-tetA(B)-ΔIS26), and one, RU3 (a sul3-associated class 1 integron with cassette array dfrA12-orfF-aadA2-cmlA1-aadA1), was embedded in a Tn21-derived element harboured by the conjugative I1 plasmid pST1030-1A. IS26 elements mediated the antimicrobial resistance gene (ARG) shuffling and this gave rise to pST1030-1A derivatives with different sets of ARGs. ST1030 also harboured two ColE1-like plasmids of which one, pST1030-2A, was mobilisable and the target of an intracellular translocation of the Tn21-derived element; the second (pST1030-3) was an orphan mob-associated oriT plasmid co-transferred with pST1030-1A and pST1030-2A. pST1030-2A and pST1030-3 also carried a parA gene and a type III restriction modification system, respectively. Overall analysis of our data reinforces the role played by IS26, Tn21-derived elements and non-conjugative plasmids in the spread of ARGs and supplies the first evidence, at least in Salmonella, for the identification of a natural isolate harbouring a three-element mobilisation system in the same cell.
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Affiliation(s)
- M Oliva
- Department of Biology, University of Bari, via Orabona, 4, 70125 Bari, Italy
| | - C Calia
- Department of Biology, University of Bari, via Orabona, 4, 70125 Bari, Italy
| | - M Ferrara
- Institute of Sciences of Food Production, National Research Council of Italy (ISPA-CNR), Via G. Amendola 122/O, 70126 Bari, Italy
| | - P D'Addabbo
- Department of Biology, University of Bari, via Orabona, 4, 70125 Bari, Italy
| | - M Scrascia
- Department of Biology, University of Bari, via Orabona, 4, 70125 Bari, Italy
| | - G Mulè
- Institute of Sciences of Food Production, National Research Council of Italy (ISPA-CNR), Via G. Amendola 122/O, 70126 Bari, Italy
| | - R Monno
- Department of Basic Medical Sciences Neurosciences and Sense Organs Medical Faculty, University of Bari Piazza G. Cesare Policlinico, 70124 Bari, Italy
| | - C Pazzani
- Department of Biology, University of Bari, via Orabona, 4, 70125 Bari, Italy.
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5
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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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Oladeinde A, Cook K, Orlek A, Zock G, Herrington K, Cox N, Plumblee Lawrence J, Hall C. Hotspot mutations and ColE1 plasmids contribute to the fitness of Salmonella Heidelberg in poultry litter. PLoS One 2018; 13:e0202286. [PMID: 30169497 PMCID: PMC6118388 DOI: 10.1371/journal.pone.0202286] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/31/2018] [Indexed: 12/14/2022] Open
Abstract
Salmonella enterica subsp. enterica serovar Heidelberg (S. Heidelberg) is a clinically-important serovar linked to food-borne illness, and commonly isolated from poultry. Investigations of a large, multistate outbreak in the USA in 2013 identified poultry litter (PL) as an important extra-intestinal environment that may have selected for specific S. Heidelberg strains. Poultry litter is a mixture of bedding materials and chicken excreta that contains chicken gastrointestinal (GI) bacteria, undigested feed, feathers, and other materials of chicken origin. In this study, we performed a series of controlled laboratory experiments which assessed the microevolution of two S. Heidelberg strains (SH-2813 and SH-116) in PL previously used to raise 3 flocks of broiler chickens. The strains are closely related at the chromosome level, differing from the reference genome by 109 and 89 single nucleotide polymorphisms/InDels, respectively. Whole genome sequencing was performed on 86 isolates recovered after 0, 1, 7 and 14 days of microevolution in PL. Only strains carrying an IncX1 (37kb), 2 ColE1 (4 and 6kb) and 1 ColpVC (2kb) plasmids survived more than 7 days in PL. Competition experiments showed that carriage of these plasmids was associated with increased fitness. This increased fitness was associated with an increased copy number of IncX1 and ColE1 plasmids. Further, all Col plasmid-bearing strains had hotspot mutations in 37 loci on the chromosome and in 3 loci on the IncX1 plasmid. Additionally, we observed a decrease in susceptibility to tobramycin, kanamycin, gentamicin, neomycin and fosfomycin for Col plasmid-bearing strains. Our study demonstrates how positive selection from poultry litter can change the evolutionary path of S. Heidelberg.
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Affiliation(s)
- Adelumola Oladeinde
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Kimberly Cook
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Alex Orlek
- Nuffield Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Greg Zock
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Kyler Herrington
- Department of Microbiology, University of Georgia, Athens, GA, United States of America
| | - Nelson Cox
- Poultry Microbiological Safety and Processing Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Jodie Plumblee Lawrence
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Carolina Hall
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
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7
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Zharikova NV, Iasakov TR, Bumazhkin BK, Patutina EO, Zhurenko EI, Korobov VV, Sagitova AI, Kuznetsov BB, Markusheva TV. Isolation and sequence analysis of pCS36-4CPA, a small plasmid from Citrobacter sp. 36-4CPA. Saudi J Biol Sci 2018; 25:660-671. [PMID: 29736141 PMCID: PMC5935869 DOI: 10.1016/j.sjbs.2016.02.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/07/2015] [Accepted: 02/08/2016] [Indexed: 11/22/2022] Open
Abstract
A small plasmid designated pCS36-4CPA with a size of 5217 base pairs and G-C content of 50.74% was isolated from Citrobacter sp. 36-4CPA. The origin of replication (ori) of the plasmid was identified as a region of about 800 bp in length with an identity of 67.1% to the ColE1 plasmid at the nucleotide level. The replication region contained typical elements of ColE1-like plasmids: RNA I and RNA II with their corresponding -10 and -35 boxes, a single-strand initiation site (ssi), and a lagging-strand termination site (terH). As seen in other ColE1-like plasmids, pCS36-4CPA carried mobilisation machinery that include mobABCD genes but it did not possess the rom gene. Analysis of the multimer resolution site (mrs) was performed and XerC and XerD binding sites were identified. Also, the 70-nt transcript Rcd of pCS36-4CPA was predicted and similarity of the transcript's secondary structure with those of the ColE1-family was shown. The cargo module of pCS36-4CPA contained three open reading frames (ORFs). Two of them (ORF5 and ORF6) showed no significant homology to any known gene sequences but contained putative THAP DNA-binding (DBD) and type II restriction endonuclease EcoO109I domains. The seventh open reading frame (ORF7) encodes YhdJ-like DNA modification methylase. The region highly homologous to pCS36-4CPA was found in the Salmonella phage SE2 genome.
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Ramsay JP, Firth N. Diverse mobilization strategies facilitate transfer of non-conjugative mobile genetic elements. Curr Opin Microbiol 2017; 38:1-9. [PMID: 28391142 DOI: 10.1016/j.mib.2017.03.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
Abstract
Conjugation is a dominant mechanism of horizontal gene transfer and substantially contributes to the plasticity and evolvability of prokaryotic genomes. The impact of conjugation on genetic flux extends well beyond self-transmissible conjugative elements, because non-conjugative 'mobilizable elements' utilize other elements' conjugative apparatus for transfer. Bacterial genome comparisons highlight plasmids as vehicles for dissemination of pathogenesis and antimicrobial-resistance determinants, but for most non-conjugative plasmids, a mobilization mechanism is not apparent. Recently we discovered many Staphylococcus aureus plasmids lacking mobilization genes carry oriT sequences that mimic those on conjugative plasmids, suggesting that significantly more elements may be mobilizable than previously recognized. Here we summarize our findings, review the diverse mobilization strategies employed by mobile genetic elements and discuss implications for future gene-transfer research.
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Affiliation(s)
- Joshua P Ramsay
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia.
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
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9
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Godziszewska J, Moncalián G, Cabezas M, Bartosik AA, de la Cruz F, Jagura-Burdzy G. Concerted action of NIC relaxase and auxiliary protein MobC in RA3 plasmid conjugation. Mol Microbiol 2016; 101:439-56. [PMID: 27101775 DOI: 10.1111/mmi.13401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2016] [Indexed: 11/29/2022]
Abstract
Conjugative transfer of the broad-host-range RA3 plasmid, the archetype of the IncU group, relies on the relaxase NIC that belongs to the as yet uncharacterized MOBP4 subfamily. NIC contains the signature motifs of HUH relaxases involved in Tyr nucleophilic attack. However, it differs in the residue involved in His activation for cation coordination and was shown here to have altered divalent cation requirements. NIC is encoded in the mobC-nic operon preceded directly by oriT, where mobC encodes an auxiliary transfer protein with a dual function: autorepressor and stimulator of conjugative transfer. Here an interplay between MobC and NIC was demonstrated. MobC is required for efficient NIC cleavage of oriT in supercoiled DNA whereas NIC assists MobC in repression of the mobC-nic operon. A 7-bp arm of IR3 (IR3a) was identified as the binding site for NIC and the crucial nucleotides in IR3a for NIC recognition were defined. Fully active oriTRA3 was delineated to a 47-bp DNA segment encompassing a conserved cleavage site sequence, the NIC binding site IR3a and the MobC binding site OM . This highly efficient RA3 conjugative system with defined requirements for minimal oriT could find ample applications in biotechnology and computational biology where simple conjugative systems are needed.
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Affiliation(s)
- Jolanta Godziszewska
- Institute of Biochemistry and Biophysics PAS, Department of Microbial Biochemistry, 02-106 Warsaw, Poland.,Warsaw University of Life Sciences (WULS-SGGW), Faculty of Human Nutrition and Consumer Sciences, Laboratory of Food Chemistry, 02-776, Warsaw, Poland
| | - Gabriel Moncalián
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, C/Albert Einstein 22, 39011, Santander, Spain
| | - Matilde Cabezas
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, C/Albert Einstein 22, 39011, Santander, Spain
| | - Aneta A Bartosik
- Institute of Biochemistry and Biophysics PAS, Department of Microbial Biochemistry, 02-106 Warsaw, Poland
| | - Fernando de la Cruz
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, C/Albert Einstein 22, 39011, Santander, Spain
| | - Grazyna Jagura-Burdzy
- Institute of Biochemistry and Biophysics PAS, Department of Microbial Biochemistry, 02-106 Warsaw, Poland
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Godziszewska J, Kulińska A, Jagura-Burdzy G. MobC of conjugative RA3 plasmid from IncU group autoregulates the expression of bicistronic mobC-nic operon and stimulates conjugative transfer. BMC Microbiol 2014; 14:235. [PMID: 25187417 PMCID: PMC4175270 DOI: 10.1186/s12866-014-0235-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/19/2014] [Indexed: 11/28/2022] Open
Abstract
Background The IncU conjugative transfer module represents highly efficient promiscuous system widespread among conjugative plasmids of different incompatibility groups. Despite its frequent occurrence the mechanisms of relaxosome formation/action are far from understood. Here we analyzed the putative transfer auxiliary protein MobC of the conjugative plasmid RA3 from the IncU incompatibility group. Results MobC is a protein of 176 amino acids encoded in the bicistronic operon mobC-nic adjacent to oriT. MobC is homologous to prokaryotic transcription factors of the ribbon-helix-helix (RHH) superfamily. Conserved LxxugxNlNQiaxxLn motif clusters MobC with the clade of conjugative transfer auxilliary proteins of MobP relaxases. MobC forms dimers in solution and autoregulates the expression of mobCp by binding to an imperfect palindromic sequence (OM) located between putative -35 and -10 motifs of the promoter. Medium-copy number test plasmid containing the oriT-mobCp region is mobilized with a high frequency by the RA3 conjugative system. The mutations introduced into OM that abolished MobC binding in vitro decreased 2-3 fold the frequency of mobilization of the test plasmids. The deletion of OM within the RA3 conjugative module had no effect on transfer if the mobC-nic operon was expressed from the heterologous promoter. If only nic was expressed from the heterologous promoter (no mobC) the conjugative transfer frequency of such plasmid was 1000-fold lower. Conclusion The MobC is an auxiliary transfer protein of dual function. It autoregulates the expression of mobC-nic operon while its presence significantly stimulates transfer efficiency. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0235-1) contains supplementary material, which is available to authorized users.
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11
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A cointegrate-like plasmid that facilitates dissemination by conjugation of the extended-spectrum β-lactamase CTX-M-17. Antimicrob Agents Chemother 2013; 57:5191-2. [PMID: 23877684 DOI: 10.1128/aac.01365-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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