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Al Mamun AAM, Kissoon K, Li YG, Hancock E, Christie PJ. The F plasmid conjutome: the repertoire of E. coli proteins translocated through an F-encoded type IV secretion system. mSphere 2024; 9:e0035424. [PMID: 38940509 PMCID: PMC11288057 DOI: 10.1128/msphere.00354-24] [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: 04/25/2024] [Accepted: 06/10/2024] [Indexed: 06/29/2024] Open
Abstract
Bacterial conjugation systems pose a major threat to human health through their widespread dissemination of mobile genetic elements (MGEs) carrying cargoes of antibiotic resistance genes. Using the Cre Recombinase Assay for Translocation (CRAfT), we recently reported that the IncFV pED208 conjugation system also translocates at least 16 plasmid-encoded proteins to recipient bacteria. Here, we deployed a high-throughput CRAfT screen to identify the repertoire of chromosomally encoded protein substrates of the pED208 system. We identified 32 substrates encoded by the Escherichia coli W3110 genome with functions associated with (i) DNA/nucleotide metabolism, (ii) stress tolerance/physiology, (iii) transcriptional regulation, or (iv) toxin inhibition. The respective gene deletions did not impact pED208 transfer proficiencies, nor did Group 1 (DNA/nucleotide metabolism) mutations detectably alter the SOS response elicited in new transconjugants upon acquisition of pED208. However, MC4100(pED208) donor cells intrinsically exhibit significantly higher SOS activation than plasmid-free MC4100 cells, and this plasmid carriage-induced stress response is further elevated in donor cells deleted of several Group 1 genes. Among 10 characterized substrates, we gained evidence of C-terminal or internal translocation signals that could function independently or synergistically for optimal protein transfer. Remarkably, nearly all tested proteins were also translocated through the IncN pKM101 and IncP RP4 conjugation systems. This repertoire of E. coli protein substrates, here termed the F plasmid "conjutome," is thus characterized by functions of potential benefit to new transconjugants, diverse TSs, and the capacity for promiscuous transfer through heterologous conjugation systems. IMPORTANCE Conjugation systems comprise a major subfamily of the type IV secretion systems (T4SSs) and are the progenitors of a second large T4SS subfamily dedicated to translocation of protein effectors. This study examined the capacity of conjugation machines to function as protein translocators. Using a high-throughput reporter screen, we determined that 32 chromosomally encoded proteins are delivered through an F plasmid conjugation system. The translocated proteins potentially enhance the establishment of the co-transferred F plasmid or mitigate mating-induced stresses. Translocation signals located C-terminally or internally conferred substrate recognition by the F system and, remarkably, many substrates also were translocated through heterologous conjugation systems. Our findings highlight the plasticity of conjugation systems in their capacities to co-translocate DNA and many protein substrates.
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Affiliation(s)
- Abu Amar M. Al Mamun
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Kimberley Kissoon
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Yang Grace Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Erin Hancock
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, Texas, USA
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Liu Z, Gao Y, Wang M, Liu Y, Wang F, Shi J, Wang Z, Li R. Adaptive evolution of plasmid and chromosome contributes to the fitness of a blaNDM-bearing cointegrate plasmid in Escherichia coli. THE ISME JOURNAL 2024; 18:wrae037. [PMID: 38438143 PMCID: PMC10976473 DOI: 10.1093/ismejo/wrae037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/08/2024] [Accepted: 03/01/2024] [Indexed: 03/06/2024]
Abstract
Large cointegrate plasmids recruit genetic features of their parental plasmids and serve as important vectors in the spread of antibiotic resistance. They are now frequently found in clinical settings, raising the issue of how to limit their further transmission. Here, we conducted evolutionary research of a large blaNDM-positive cointegrate within Escherichia coli C600, and discovered that adaptive evolution of chromosome and plasmid jointly improved bacterial fitness, which was manifested as enhanced survival ability for in vivo and in vitro pairwise competition, biofilm formation, and gut colonization ability. From the plasmid aspect, large-scale DNA fragment loss is observed in an evolved clone. Although the evolved plasmid imposes a negligible fitness cost on host bacteria, its conjugation frequency is greatly reduced, and the deficiency of anti-SOS gene psiB is found responsible for the impaired horizontal transferability rather than the reduced fitness cost. These findings unveil an evolutionary strategy in which the plasmid horizontal transferability and fitness cost are balanced. From the chromosome perspective, all evolved clones exhibit parallel mutations in the transcriptional regulatory stringent starvation Protein A gene sspA. Through a sspA knockout mutant, transcriptome analysis, in vitro transcriptional activity assay, RT-qPCR, motility test, and scanning electron microscopy techniques, we demonstrated that the mutation in sspA reduces its transcriptional inhibitory capacity, thereby improving bacterial fitness, biofilm formation ability, and gut colonization ability by promoting bacterial flagella synthesis. These findings expand our knowledge of how cointegrate plasmids adapt to new bacterial hosts.
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Affiliation(s)
- Ziyi Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Jiangsu Key Lab of Zoonosis, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- College of Animal Science and Technology & College of Veterinary medicine, Zhejiang Agriculture and Forestry University, Hangzhou, 311300 Zhejiang Province, People's Republic of China
| | - Yanyun Gao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Jiangsu Key Lab of Zoonosis, Yangzhou, 225009 Jiangsu Province, People's Republic of China
| | - Mianzhi Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Jiangsu Key Lab of Zoonosis, Yangzhou, 225009 Jiangsu Province, People's Republic of China
| | - Yuan Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Jiangsu Key Lab of Zoonosis, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
| | - Fulin Wang
- Department of Pathogen Biology, School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 Jiangsu Province, People's Republic of China
| | - Jing Shi
- Department of Pathogen Biology, School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 Jiangsu Province, People's Republic of China
| | - Zhiqiang Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Jiangsu Key Lab of Zoonosis, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Institute of Agricultural Science and Technology Development, Yangzhou, 225009 Jiangsu Province, People's Republic of China
| | - Ruichao Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Jiangsu Key Lab of Zoonosis, Yangzhou, 225009 Jiangsu Province, People's Republic of China
- Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009 Jiangsu Province, People's Republic of China
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3
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Ryan ME, Damke PP, Shaffer CL. DNA Transport through the Dynamic Type IV Secretion System. Infect Immun 2023; 91:e0043622. [PMID: 37338415 PMCID: PMC10353360 DOI: 10.1128/iai.00436-22] [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] [Indexed: 06/21/2023] Open
Abstract
The versatile type IV secretion system (T4SS) nanomachine plays a pivotal role in bacterial pathogenesis and the propagation of antibiotic resistance determinants throughout microbial populations. In addition to paradigmatic DNA conjugation machineries, diverse T4SSs enable the delivery of multifarious effector proteins to target prokaryotic and eukaryotic cells, mediate DNA export and uptake from the extracellular milieu, and in rare examples, facilitate transkingdom DNA translocation. Recent advances have identified new mechanisms underlying unilateral nucleic acid transport through the T4SS apparatus, highlighting both functional plasticity and evolutionary adaptations that enable novel capabilities. In this review, we describe the molecular mechanisms underscoring DNA translocation through diverse T4SS machineries, emphasizing the architectural features that implement DNA exchange across the bacterial membrane and license transverse DNA release across kingdom boundaries. We further detail how recent studies have addressed outstanding questions surrounding the mechanisms by which nanomachine architectures and substrate recruitment strategies contribute to T4SS functional diversity.
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Affiliation(s)
- Mackenzie E. Ryan
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Prashant P. Damke
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, USA
| | - Carrie L. Shaffer
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, USA
- Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, Kentucky, USA
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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Dhaouadi S, Romdhani A, Bouglita W, Chedli S, Chaari S, Soufi L, Cherif A, Mnif W, Abbassi MS, Elandoulsi RB. High Biofilm-Forming Ability and Clonal Dissemination among Colistin-Resistant Escherichia coli Isolates Recovered from Cows with Mastitis, Diarrheic Calves, and Chickens with Colibacillosis in Tunisia. Life (Basel) 2023; 13:life13020299. [PMID: 36836656 PMCID: PMC9959077 DOI: 10.3390/life13020299] [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: 12/07/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Escherichia coli (E. coli) is one of the main etiological agents responsible for bovine mastitis (BM), neonatal calf diarrhea (NCD), and avian colibacillosis (AC). This study aimed to assess resistance and virulence genes content, biofilm-forming ability, phylogenetic groups, and genetic relatedness in E. coli isolates recovered from clinical cases of BM, NCD, and AC. MATERIALS/METHODS A total of 120 samples including samples of milk (n = 70) and feces (n = 50) from cows with BM and calves with NCD, respectively, were collected from different farms in Northern Tunisia. Bacterial isolation and identification were performed. Then, E. coli isolates were examined by disk diffusion and broth microdilution method for their antimicrobial susceptibility and biofilm-forming ability. PCR was used to detect antimicrobial resistance genes (ARGs), virulence genes (VGs), phylogenetic groups, and Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) for their clonal relationship. RESULTS Among the 120 samples, 67 E. coli isolates (25 from BM, 22 from AC, and 20 from NCD) were collected. Overall, 83.6% of isolates were multidrug resistant. Thirty-six (53.73%) isolates were phenotypically colistin-resistant (CREC), 28.3% (19/67) were ESBL producers (ESBL-EC), and forty-nine (73.1%) formed biofilm. The blaTEM gene was found in 73.7% (14/19) of isolates from the three diseases, whilst the blaCTXM-g-1 gene was detected in 47.3% (9/19) of isolates, all from AC. The most common VG was the fimA gene (26/36, 72.2%), followed by aer (12/36, 33.3%), cnf1 (6/36, 16.6%), papC (4/36, 11.1%), and stx1 and stx2 genes (2/36; 5.5% for each). Phylogenetic analysis showed that isolates belonged to three groups: A (20/36; 55.5%), B2 (7/36; 19.4%), and D (6/36; 16.6%). Molecular typing by ERIC-PCR showed high genetic diversity of CREC and ESBL E. coli isolates from the three animal diseases and gave evidence of their clonal dissemination within farms in Tunisia. CONCLUSION The present study sheds new light on the biofilm-forming ability and clonality within CREC and ESBL-EC isolated from three different animal diseases in Tunisian farm animals.
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Affiliation(s)
- Sana Dhaouadi
- ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
| | - Amel Romdhani
- ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
| | - Wafa Bouglita
- Institut Supérieur de Biotechnologie de Sidi Thabet, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
| | - Salsabil Chedli
- ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
| | - Soufiene Chaari
- MEDIVET, Immeuble les Mimosas, 159 Avenue de l’UMA, La Soukra 2036, Tunisia
| | - Leila Soufi
- ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
| | - Ameur Cherif
- ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
| | - Wissem Mnif
- Department of Chemistry, Faculty of Sciences and Arts in Balgarn, University of Bisha, P.O. Box 199, Bisha 61922, Saudi Arabia
- Correspondence: (W.M.); (R.B.E.)
| | - Mohamed Salah Abbassi
- Institute of Veterinary Research of Tunisia, University of Tunis El Manar, Tunis 1006, Tunisia
- Laboratory of Bacteriological Research, Tunis 1006, Tunisia
| | - Ramzi Boubaker Elandoulsi
- ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, University of Manouba, Ariana 2020, Tunisia
- Correspondence: (W.M.); (R.B.E.)
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Al Mamun AAM, Kissoon K, Kishida K, Shropshire WC, Hanson B, Christie PJ. IncFV plasmid pED208: Sequence analysis and evidence for translocation of maintenance/leading region proteins through diverse type IV secretion systems. Plasmid 2022; 123-124:102652. [PMID: 36228885 PMCID: PMC10018792 DOI: 10.1016/j.plasmid.2022.102652] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/02/2022] [Accepted: 10/04/2022] [Indexed: 12/04/2022]
Abstract
Two phylogenetically distantly-related IncF plasmids, F and pED208, serve as important models for mechanistic and structural studies of F-like type IV secretion systems (T4SSFs) and F pili. Here, we present the pED208 sequence and compare it to F and pUMNF18, the closest match to pED208 in the NCBI database. As expected, gene content of the three cargo regions varies extensively, although the maintenance/leading regions (MLRs) and transfer (Tra) regions also carry novel genes or motifs with predicted modulatory effects on plasmid stability, dissemination and host range. By use of a Cre recombinase assay for translocation (CRAfT), we recently reported that pED208-carrying donors translocate several products of the MLR (ParA, ParB1, ParB2, SSB, PsiB, PsiA) intercellularly through the T4SSF. Here, we extend these findings by reporting that pED208-carrying donors translocate 10 additional MLR proteins during conjugation. In contrast, two F plasmid-encoded toxin components of toxin-antitoxin (TA) modules, CcdB and SrnB, were not translocated at detectable levels through the T4SSF. Remarkably, most or all of the pED208-encoded MLR proteins and CcdB and SrnB were translocated through heterologous T4SSs encoded by IncN and IncP plasmids pKM101 and RP4, respectively. Together, our sequence analyses underscore the genomic diversity of the F plasmid superfamily, and our experimental data demonstrate the promiscuous nature of conjugation machines for protein translocation. Our findings raise intriguing questions about the nature of T4SS translocation signals and of the biological and evolutionary consequences of conjugative protein transfer.
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Affiliation(s)
- Abu Amar M Al Mamun
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, McGovern School of Medicine, Fannin St, Houston, TX 77030, United States of America.
| | - Kimberly Kissoon
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, McGovern School of Medicine, Fannin St, Houston, TX 77030, United States of America
| | - Kouhei Kishida
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, McGovern School of Medicine, Fannin St, Houston, TX 77030, United States of America
| | - William C Shropshire
- Center for Antimicrobial Resistance and Microbial Genomics, University of Texas Health Science Center, McGovern School of Medicine, Houston, TX, USA; Center for Infectious Diseases, University of Texas Health Science Center, School of Public Health, Houston, TX, USA
| | - Blake Hanson
- Center for Antimicrobial Resistance and Microbial Genomics, University of Texas Health Science Center, McGovern School of Medicine, Houston, TX, USA; Center for Infectious Diseases, University of Texas Health Science Center, School of Public Health, Houston, TX, USA
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, McGovern School of Medicine, Fannin St, Houston, TX 77030, United States of America.
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6
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Characterization of the DNA Binding Domain of StbA, A Key Protein of A New Type of DNA Segregation System. J Mol Biol 2022; 434:167752. [PMID: 35868361 DOI: 10.1016/j.jmb.2022.167752] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 11/21/2022]
Abstract
Low-copy-number plasmids require sophisticated genetic devices to achieve efficient segregation of plasmid copies during cell division. Plasmid R388 uses a unique segregation mechanism, based on StbA, a small multifunctional protein. StbA is the key protein in a segregation system not involving a plasmid-encoded NTPase partner, it regulates the expression of several plasmid operons, and it is the main regulator of plasmid conjugation. The mechanisms by which StbA, together with the centromere-like sequence stbS, achieves segregation, is largely uncharacterized. To better understand the molecular basis of R388 segregation, we determined the crystal structure of the conserved N-terminal domain of StbA to 1.9 Å resolution. It folds into an HTH DNA-binding domain, structurally related to that of the PadR subfamily II of transcriptional regulators. StbA is organized in two domains. Its N-terminal domain carries the specific stbS DNA binding activity. A truncated version of StbA, deleted of its C-terminal domain, displays only partial activities in vivo, indicating that the non-conserved C-terminal domain is required for efficient segregation and subcellular plasmid positioning. The structure of StbA DNA-binding domain also provides some insight into how StbA monomers cooperate to repress transcription by binding to the stbDR and to form the segregation complex with stbS.
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7
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Light Regulates Acinetobacter baumannii Chromosomal and pAB3 Plasmid Genes at 37°C. J Bacteriol 2022; 204:e0003222. [PMID: 35604222 DOI: 10.1128/jb.00032-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The opportunistic pathogen A. baumannii has a remarkable capacity to persist in the hospital environment and cause devastating human infections. This capacity can be attributed partly to the sensing and regulatory systems that enable this pathogen to modify its physiology based on environmental cues. One of the signals that A. baumannii senses and responds to is light through the sensing and regulatory roles of the BlsA photoreceptor protein in cells cultured at temperatures below 30°C. This report presents evidence that a light stimulon is operational at 37°C, a condition at which the BlsA production and activity are drastically impaired. Global transcriptional analysis showed that the 37°C light stimulon includes the differential expression of chromosomal genes encoding a wide range of functions that are known to be involved in the adaptation to different metabolic conditions, as well as virulence and persistence in the host and the medical environment. Unexpectedly, the 37°C light stimulon also includes the differential expression of conjugation functions encoded by pAB3 plasmid genes. Our work further demonstrates that the TetR1 and H-NS regulators encoded by this conjugative plasmid control the expression of H2O2 resistance and surface motility, respectively. Furthermore, our data showed that pAB3 has an overall negative effect on the expression of these phenotypes and plays no significant virulence role. Although the nature of the bacterial factors and the mechanisms by which the regulation is attained at 37°C remain unknown, taken together, our work expands the current knowledge about light sensing and gene regulation in A. baumannii. IMPORTANCE As a facultative pathogen, Acinetobacter baumannii persists in various environments by sensing different environmental cues, including light. This report provides evidence of light-dependent regulation at 37°C of the expression of genes coding for a wide range of functions, including those involved in the conjugation of the pAB3 plasmid. Although this plasmid affects the expression of virulence traits when tested under laboratory conditions, it does not have a significant impact when tested using ex vivo and in vivo experimental models. These findings provide a better understanding of the interplay between light regulation and plasmid persistence in the pathobiology of A. baumannii.
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8
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Kishida K, Bosserman RE, Harb L, Khara P, Song L, Hu B, Zeng L, Christie PJ. Contributions of F‐specific Subunits to the F
Plasmid‐Encoded
Type
IV
Secretion System and F pilus. Mol Microbiol 2022; 117:1275-1290. [DOI: 10.1111/mmi.14908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/26/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Kouhei Kishida
- Department of Microbiology and Molecular Genetics McGovern Medical School 6431 Fannin St, Houston, Texas 77030
| | - Rachel E. Bosserman
- Department of Microbiology and Molecular Genetics McGovern Medical School 6431 Fannin St, Houston, Texas 77030
- Current address: Department of Medicine, Division of Infectious Diseases Washington School of Medicine St. Louis, MO, 63110
| | - Laith Harb
- Department of Biochemistry and Biophysics, Texas A&M University College Station TX, 77843 USA
- Center for Phage Technology, Texas A&M University College Station TX, 77843 USA
| | - Pratick Khara
- Department of Microbiology and Molecular Genetics McGovern Medical School 6431 Fannin St, Houston, Texas 77030
| | - Liqiang Song
- Department of Microbiology and Molecular Genetics McGovern Medical School 6431 Fannin St, Houston, Texas 77030
| | - Bo Hu
- Department of Microbiology and Molecular Genetics McGovern Medical School 6431 Fannin St, Houston, Texas 77030
| | - Lanying Zeng
- Department of Biochemistry and Biophysics, Texas A&M University College Station TX, 77843 USA
- Center for Phage Technology, Texas A&M University College Station TX, 77843 USA
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics McGovern Medical School 6431 Fannin St, Houston, Texas 77030
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9
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Callaghan MM, Koch B, Hackett KT, Klimowicz AK, Schaub RE, Krasnogor N, Dillard JP. Expression, Localization, and Protein Interactions of the Partitioning Proteins in the Gonococcal Type IV Secretion System. Front Microbiol 2021; 12:784483. [PMID: 34975804 PMCID: PMC8716806 DOI: 10.3389/fmicb.2021.784483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/24/2021] [Indexed: 11/13/2022] Open
Abstract
Partitioning proteins are well studied as molecular organizers of chromosome and plasmid segregation during division, however little is known about the roles partitioning proteins can play within type IV secretion systems. The single-stranded DNA (ssDNA)-secreting gonococcal T4SS has two partitioning proteins, ParA and ParB. These proteins work in collaboration with the relaxase TraI as essential facilitators of type IV secretion. Bacterial two-hybrid experiments identified interactions between each partitioning protein and the relaxase. Subcellular fractionation demonstrated that ParA is found in the cellular membrane, whereas ParB is primarily in the membrane, but some of the protein is in the soluble fraction. Since TraI is known to be membrane-associated, these data suggest that the gonococcal relaxosome is a membrane-associated complex. In addition, we found that translation of ParA and ParB is controlled by an RNA switch. Different mutations within the stem-loop sequence predicted to alter folding of this RNA structure greatly increased or decreased levels of the partitioning proteins.
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Affiliation(s)
- Melanie M. Callaghan
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
| | - Birgit Koch
- Interdisciplinary Computing and Complex BioSystems (ICOS), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Kathleen T. Hackett
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
| | - Amy K. Klimowicz
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
| | - Ryan E. Schaub
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
| | - Natalio Krasnogor
- Interdisciplinary Computing and Complex BioSystems (ICOS), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Joseph P. Dillard
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
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10
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Javed S, Mirani ZA, Pirzada ZA. Phylogenetic Group B2 Expressed Significant Biofilm Formation among Drug Resistant Uropathogenic Escherichia coli. Libyan J Med 2021; 16:1845444. [PMID: 33170767 PMCID: PMC7671661 DOI: 10.1080/19932820.2020.1845444] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/29/2020] [Indexed: 10/31/2022] Open
Abstract
Biofilm is an important virulent marker attributed to the development of urinary tract infections (UTIs) by uropathogenic E. coli (UPEC). Drug-resistant and biofilm-producing UPEC are highly problematic causing catheter-associated or recurrent UTIs with significant morbidity and mortality. The aim of the current study was to investigate the prevalence of biofilm formation and phylogenetic groups in drug-resistant UPEC to predict their ability to cause disease. This prospective study was conducted at the Department of Microbiology, University of Karachi from January to June 2019. A total of 50 highly drug-resistant UPEC were selected for this study. UPEC isolates were screened to form biofilm by Congo-red agar (CRA) and microtiter plate (MTP) technique. The representative biofilm-producing isolates were analysed by scanning electron microscopy (SEM) monitoring. Phylogenetic analysis was done by PCR method based on two preserved genes; chuA, yjaA and TspE4-C2 DNA fragment. On CRA 34 (68%) UPEC were slime producers, while on MTP 20 (40%) were strong biofilm producers, 19 (38%) moderate and 11 (22%) were low to negligible biofilm producers. Molecular typing confirmed that phylogenetic group B2 was prevalent in drug resistant UPEC strains. Pathogenic strains belonged to phylogenetic group B2 and D were found to have greater biofilm forming ability as compare to non-pathogenic commensal strains that belonged to phylogenetic group A. Our results indicate that biofilm formation vary in drug resistant UPEC belonged to different phylogenetic groups. This study indicates possible link between in vitro biofilm formation and phylogenetic groups of UPEC, therefore this knowledge might be helpful to predict the pathogenic potential of UPEC and help design strategies for controlling UTIs.
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Affiliation(s)
- Saima Javed
- Department of Microbiology, University of Karachi, Karachi, Pakistan
| | - Zulfiqar Ali Mirani
- Pakistan Council of Scientific and Industrial Research Laboratories Complex, Karachi, Pakistan
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11
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Wongpayak P, Meesungnoen O, Saejang S, Subsoontorn P. A highly effective and self-transmissible CRISPR antimicrobial for elimination of target plasmids without antibiotic selection. PeerJ 2021; 9:e11996. [PMID: 34567840 PMCID: PMC8428258 DOI: 10.7717/peerj.11996] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/27/2021] [Indexed: 01/21/2023] Open
Abstract
The use of CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein) for sequence-specific elimination of bacteria or resistance genes is a powerful tool for combating antibiotic resistance. However, this approach requires efficient delivery of CRISPR/Cas DNA cassette(s) into the targeted bacterial population. Compared to phage transduction, plasmid conjugation can deliver DNA to a broader host range but often suffers from low delivery efficiency. Here, we developed multi-plasmid conjugation systems for efficient CRISPR/Cas delivery, target DNA elimination and plasmid replacement. The CRISPR/Cas system, delivered via a broad-host-range R1162 mobilizable plasmid, specifically eliminated the targeted plasmid in recipient cells. A self-transmissible RK2 helper plasmid facilitated the spread of mobilizable CRISPR/Cas. The replacement of the target plasmid with another plasmid from the same compatibility group helped speed up target plasmid elimination especially when the target plasmid was also mobilizable. Together, we showed that up to 100% of target plasmid from the entire recipient population could be replaced even at a low (1:180) donor-to-recipient ratio and in the absence of transconjugant selection. Such an ability to modify genetic content of microbiota efficiently in the absence of selection will be critical for future development of CRISPR antimicrobials as well as genetic tools for in situ microbiome engineering.
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Affiliation(s)
- Panjaporn Wongpayak
- Department of Biochemistry, Faculty of Medical Science, Naresuan University, Muang Phitsanulok, Phitsanulok, Thailand
| | | | - Somchai Saejang
- Department of Biochemistry, Faculty of Medical Science, Naresuan University, Muang Phitsanulok, Phitsanulok, Thailand
| | - Pakpoom Subsoontorn
- Department of Biochemistry, Faculty of Medical Science, Naresuan University, Muang Phitsanulok, Phitsanulok, Thailand
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12
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Huang CJ, Wu TL, Zheng PX, Ou JY, Ni HF, Lin YC. Comparative Genomic Analysis Uncovered Evolution of Pathogenicity Factors, Horizontal Gene Transfer Events, and Heavy Metal Resistance Traits in Citrus Canker Bacterium Xanthomonas citri subsp. citri. Front Microbiol 2021; 12:731711. [PMID: 34557177 PMCID: PMC8453159 DOI: 10.3389/fmicb.2021.731711] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/18/2021] [Indexed: 12/30/2022] Open
Abstract
Background: Worldwide citrus production is severely threatened by Asiatic citrus canker which is caused by the proteobacterium Xanthomonas citri subsp. citri. Foliar sprays of copper-based bactericides are frequently used to control plant bacterial diseases. Despite the sequencing of many X. citri strains, the genome diversity and distribution of genes responsible for metal resistance in X. citri subsp. citri strains from orchards with different management practices in Taiwan are not well understood. Results: The genomes of three X. citri subsp. citri strains including one copper-resistant strain collected from farms with different management regimes in Taiwan were sequenced by Illumina and Nanopore sequencing and assembled into complete circular chromosomes and plasmids. CRISPR spoligotyping and phylogenomic analysis indicated that the three strains were located in the same phylogenetic lineages and shared ∼3,000 core-genes with published X. citri subsp. citri strains. These strains differed mainly in the CRISPR repeats and pathogenicity-related plasmid-borne transcription activator-like effector (TALE)-encoding pthA genes. The copper-resistant strain has a unique, large copper resistance plasmid due to an unusual ∼40 kbp inverted repeat. Each repeat contains a complete set of the gene cluster responsible for copper and heavy metal resistance. Conversely, the copper sensitive strains carry no metal resistance genes in the plasmid. Through comparative analysis, the origin and evolution of the metal resistance clusters was resolved. Conclusion: Chromosomes remained constant among three strains collected in Taiwan, but plasmids likely played an important role in maintaining pathogenicity and developing bacterial fitness in the field. The evolution of pathogenicity factors and horizontal gene transfer events were observed in the three strains. These data suggest that agricultural management practices could be a potential trigger for the evolution of citrus canker pathogens. The decrease in the number of CRISPR repeats and pthA genes might be the result of adaptation to a less stressful environment. The metal resistance genes in the copper resistant X. citri strain likely originated from the Mauritian strain not the local copper-resistant X. euvesicatoria strain. This study highlights the importance of plasmids as 'vehicles' for exchanging genetic elements between plant pathogenic bacteria and contributing to bacterial adaptation to the environment.
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Affiliation(s)
- Chien-Jui Huang
- Department of Plant Medicine, National Chiayi University, Chiayi, Taiwan
| | - Ting-Li Wu
- Biotechnology Center in Southern Taiwan, Agricultural Biotechnology Research Center, Academia Sinica, Tainan, Taiwan
| | - Po-Xing Zheng
- Biotechnology Center in Southern Taiwan, Agricultural Biotechnology Research Center, Academia Sinica, Tainan, Taiwan
| | - Jheng-Yang Ou
- Biotechnology Center in Southern Taiwan, Agricultural Biotechnology Research Center, Academia Sinica, Tainan, Taiwan
| | - Hui-Fang Ni
- Department of Plant Protection, Chiayi Agricultural Experiment Station, Taiwan Agricultural Research Institute, Chiayi, Taiwan
| | - Yao-Cheng Lin
- Biotechnology Center in Southern Taiwan, Agricultural Biotechnology Research Center, Academia Sinica, Tainan, Taiwan
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13
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Protein Transfer through an F Plasmid-Encoded Type IV Secretion System Suppresses the Mating-Induced SOS Response. mBio 2021; 12:e0162921. [PMID: 34253063 PMCID: PMC8406263 DOI: 10.1128/mbio.01629-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Bacterial type IV secretion systems (T4SSs) mediate the conjugative transfer of mobile genetic elements (MGEs) and their cargoes of antibiotic resistance and virulence genes. Here, we report that the pED208-encoded T4SS (TrapED208) translocates not only this F plasmid but several plasmid-encoded proteins, including ParA, ParB1, single-stranded DNA-binding protein SSB, ParB2, PsiB, and PsiA, to recipient cells. Conjugative protein translocation through the TrapED208 T4SS required engagement of the pED208 relaxosome with the TraD substrate receptor or coupling protein. T4SSs translocate MGEs as single-stranded DNA intermediates (T-strands), which triggers the SOS response in recipient cells. Transfer of pED208 deleted of psiB or ssb, which, respectively, encode the SOS inhibitor protein PsiB and single-stranded DNA-binding protein SSB, elicited a significantly stronger SOS response than pED208 or mutant plasmids deleted of psiA, parA, parB1, or parB2. Conversely, translocation of PsiB or SSB, but not PsiA, through the TrapED208 T4SS suppressed the mating-induced SOS response. Our findings expand the repertoire of known substrates of conjugation systems to include proteins with functions associated with plasmid maintenance. Furthermore, for this and other F-encoded Tra systems, docking of the DNA substrate with the TraD receptor appears to serve as a critical activating signal for protein translocation. Finally, the observed effects of PsiB and SSB on suppression of the mating-induced SOS response establishes a novel biological function for conjugative protein translocation and suggests the potential for interbacterial protein translocation to manifest in diverse outcomes influencing bacterial communication, physiology, and evolution.
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14
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Mitura M, Lewicka E, Godziszewska J, Adamczyk M, Jagura-Burdzy G. Alpha-Helical Protein KfrC Acts as a Switch between the Lateral and Vertical Modes of Dissemination of Broad-Host-Range RA3 Plasmid from IncU (IncP-6) Incompatibility Group. Int J Mol Sci 2021; 22:4880. [PMID: 34063039 PMCID: PMC8124265 DOI: 10.3390/ijms22094880] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/27/2021] [Accepted: 05/03/2021] [Indexed: 12/24/2022] Open
Abstract
KfrC proteins are encoded by the conjugative broad-host-range plasmids that also encode alpha-helical filament-forming KfrA proteins as exemplified by the RA3 plasmid from the IncU incompatibility group. The RA3 variants impaired in kfrA, kfrC, or both affected the host's growth and demonstrated the altered stability in a species-specific manner. In a search for partners of the alpha-helical KfrC protein, the host's membrane proteins and four RA3-encoded proteins were found, including the filamentous KfrA protein, segrosome protein KorB, and the T4SS proteins, the coupling protein VirD4 and ATPase VirB4. The C-terminal, 112-residue dimerization domain of KfrC was involved in the interactions with KorB, the master player of the active partition, and VirD4, a key component of the conjugative transfer process. In Pseudomonas putida, but not in Escherichia coli, the lack of KfrC decreased the stability but improved the transfer ability. We showed that KfrC and KfrA were involved in the plasmid maintenance and conjugative transfer and that KfrC may play a species-dependent role of a switch between vertical and horizontal modes of RA3 spreading.
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Affiliation(s)
- Monika Mitura
- Laboratory of DNA Segregation and Cell Cycle of Proteobacteria, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; (M.M.); (E.L.); (J.G.)
| | - Ewa Lewicka
- Laboratory of DNA Segregation and Cell Cycle of Proteobacteria, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; (M.M.); (E.L.); (J.G.)
| | - Jolanta Godziszewska
- Laboratory of DNA Segregation and Cell Cycle of Proteobacteria, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; (M.M.); (E.L.); (J.G.)
| | - Malgorzata Adamczyk
- Faculty of Chemistry, Chair of Drug and Cosmetics Biotechnology, Warsaw University of Technology, 00-664 Warsaw, Poland;
| | - Grazyna Jagura-Burdzy
- Laboratory of DNA Segregation and Cell Cycle of Proteobacteria, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; (M.M.); (E.L.); (J.G.)
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15
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Abstract
The bacterial type IV secretion systems (T4SSs) are a functionally diverse superfamily of secretion systems found in many species of bacteria. Collectively, the T4SSs translocate DNA and monomeric and multimeric protein substrates to bacterial and eukaryotic cell types. T4SSs are composed of two large subfamilies, the conjugation machines and the effector translocators that transmit their cargoes through establishment of direct donor-target cell contacts, and a third small subfamily capable of importing or exporting substrates from or to the milieu. This review summarizes recent mechanistic and structural findings that are shedding new light on how T4SSs have evolved such functional diversity. Translocation signals are now known to be located C terminally or embedded internally in structural folds; these signals in combination with substrate-associated adaptor proteins mediate the docking of specific substrate repertoires to cognate VirD4-like receptors. For the Legionella pneumophila Dot/Icm system, recent work has elucidated the structural basis for adaptor-dependent substrate loading onto the VirD4-like DotL receptor. Advances in definition of T4SS machine structures now allow for detailed comparisons of nanomachines closely related to the Agrobacterium tumefaciens VirB/VirD4 T4SS with those more distantly related, e.g., the Dot/Icm and Helicobacter pylori Cag T4SSs. Finally, it is increasingly evident that T4SSs have evolved a variety of mechanisms dependent on elaboration of conjugative pili, membrane tubes, or surface adhesins to establish productive contacts with target cells. T4SSs thus have evolved extreme functional diversity through a plethora of adaptations impacting substrate selection, machine architecture, and target cell binding.
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16
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Ramalingam V, Raja S, Sundaramahalingam S, Rajaram R. Chemical fabrication of graphene oxide nanosheets attenuates biofilm formation of human clinical pathogens. Bioorg Chem 2018; 83:326-335. [PMID: 30396117 DOI: 10.1016/j.bioorg.2018.10.052] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 10/03/2018] [Accepted: 10/26/2018] [Indexed: 11/17/2022]
Abstract
Graphene oxide (GO) has been recently attracted considerable interest for its potential applications in physical, chemical and biological properties. In the present study, the GO nanosheets were prepared by a chemical exfoliation technique using a modified Hummers method. Initially, the prepared GO nanosheets were confirmed by UV-vis spectroscopy and further characterized by FE-SEM, Edax, HR-TEM and SAED that demonstrated the formation of GO nanosheets with few layers flat sheet structure with hexagonal lattice crystalline nature. The FTIR spectra revealed the presence of various oxygen containing functional groups has been produced from graphite plane by exfoliation technique. The prepared GO nanosheets showed excellent antibiotic resistant activity against planktonic bacteria and more effective to damage the established biofilms and inhibits the biofilm formation of human clinical pathogens like E. coli and P. aeruginosa. Further, the GO nanosheets were found to be non-toxic to normal mammalian cells and there are no apparent morphological changes were observed in control and treated cells. In conclusion, GO nanosheets were effectively preventing the formation of biofilms and kills the represent bacteria that suggested the GO nanosheets could be used for the prevention and treatment of biofilm-related infections.
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Affiliation(s)
- Vaikundamoorthy Ramalingam
- DNA Barcoding and Marine Genomics Laboratory, Department of Marine Science, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India
| | - Sakthivel Raja
- Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India
| | - Subramaniam Sundaramahalingam
- Department of Electrical and Electronics Engineering, Mepco Schlenk Engineering College, Sivakasi, Tamil Nadu, India
| | - Rajendran Rajaram
- DNA Barcoding and Marine Genomics Laboratory, Department of Marine Science, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India.
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17
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Zhao H, Chen W, Xu X, Zhou X, Shi C. Transmissible ST3-IncHI2 Plasmids Are Predominant Carriers of Diverse Complex IS 26-Class 1 Integron Arrangements in Multidrug-Resistant Salmonella. Front Microbiol 2018; 9:2492. [PMID: 30405560 PMCID: PMC6206278 DOI: 10.3389/fmicb.2018.02492] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 09/28/2018] [Indexed: 12/14/2022] Open
Abstract
Diverse mobile genetic elements (MGEs) including plasmids, insertion sequences, and integrons play an important role in the occurrence and spread of multidrug resistance (MDR) in bacteria. It was found in previous studies that IS26 and class 1 integrons integrated on plasmids to speed the dissemination of antibiotic-resistance genes in Salmonella. It is aimed to figure out the patterns of specific genetic arrangements between IS26 and class 1 integrons located in plasmids in MDR Salmonella in this study. A total of 74 plasmid-harboring Salmonella isolates were screened for the presence of IS26 by PCR amplification, and 39 were IS26-positive. Among them, 37 isolates were resistant to at least one antibiotic. The thirty-seven antibiotic-resistant isolates were further involved in PCR detection of class 1 integrons and variable regions, and all were positive for class 1 integrons. Six IS26-class 1 integron arrangements with IS26 inserted into the upstream or downstream of class 1 integrons were characterized. Eight combinations of these IS26-class 1 integron arrangements were identified among 31 antibiotic-resistant isolates. Multidrug-resistance plasmids of the IncHI2 incompatibility group were dominant, which all belonged to ST3 by plasmid double locus sequence typing. These 21 IncHI2-positive isolates harbored six complex IS26-class 1 integron arrangement patterns. Conjugation assays and Southern blot hybridizations confirmed that conjugative multidrug-resistance IncHI2 plasmids harbored the different complex IS26-class 1 integron arrangements. The conjugation frequency of IncHI2 plasmids transferring alone was 10−5-10−6, reflecting that different complex IS26-class 1 integron arrangement patterns didn't significantly affect conjugation frequency (P > 0.05). These data suggested that class 1 integrons represent the hot spot for IS26 insertion, forming diverse MDR loci. And ST3-IncHI2 was the major plasmid lineage contributing to the horizontal transfer of composite IS26-class 1 integron MDR elements in Salmonella.
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Affiliation(s)
- Hang Zhao
- State Key Laboratory of Microbial Metabolism, MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Wenyao Chen
- State Key Laboratory of Microbial Metabolism, MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Xuebin Xu
- Shanghai Municipal Center for Disease Control & Prevention, Shanghai, China
| | - Xiujuan Zhou
- State Key Laboratory of Microbial Metabolism, MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Chunlei Shi
- State Key Laboratory of Microbial Metabolism, MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
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18
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Grohmann E, Christie PJ, Waksman G, Backert S. Type IV secretion in Gram-negative and Gram-positive bacteria. Mol Microbiol 2018; 107:455-471. [PMID: 29235173 PMCID: PMC5796862 DOI: 10.1111/mmi.13896] [Citation(s) in RCA: 225] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/07/2017] [Accepted: 12/09/2017] [Indexed: 02/06/2023]
Abstract
Type IV secretion systems (T4SSs) are versatile multiprotein nanomachines spanning the entire cell envelope in Gram-negative and Gram-positive bacteria. They play important roles through the contact-dependent secretion of effector molecules into eukaryotic hosts and conjugative transfer of mobile DNA elements as well as contact-independent exchange of DNA with the extracellular milieu. In the last few years, many details on the molecular mechanisms of T4SSs have been elucidated. Exciting structures of T4SS complexes from Escherichia coli plasmids R388 and pKM101, Helicobacter pylori and Legionella pneumophila have been solved. The structure of the F-pilus was also reported and surprisingly revealed a filament composed of pilin subunits in 1:1 stoichiometry with phospholipid molecules. Many new T4SSs have been identified and characterized, underscoring the structural and functional diversity of this secretion superfamily. Complex regulatory circuits also have been shown to control T4SS machine production in response to host cell physiological status or a quorum of bacterial recipient cells in the vicinity. Here, we summarize recent advances in our knowledge of 'paradigmatic' and emerging systems, and further explore how new basic insights are aiding in the design of strategies aimed at suppressing T4SS functions in bacterial infections and spread of antimicrobial resistances.
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Affiliation(s)
- Elisabeth Grohmann
- Beuth University of Applied Sciences Berlin, Life Sciences and Technology, D-13347 Berlin, Germany
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, The University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, USA
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 7HX, United Kingdom
| | - Steffen Backert
- Friedrich Alexander University Erlangen-Nuremberg, Department of Biology, Division of Microbiology, Staudtstrasse 5, D-91058 Erlangen, Germany
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19
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Sprenger H, Kienesberger S, Pertschy B, Pöltl L, Konrad B, Bhutada P, Vorkapic D, Atzmüller D, Feist F, Högenauer C, Gorkiewicz G, Zechner EL. Fic Proteins of Campylobacter fetus subsp. venerealis Form a Network of Functional Toxin-Antitoxin Systems. Front Microbiol 2017; 8:1965. [PMID: 29089929 PMCID: PMC5651007 DOI: 10.3389/fmicb.2017.01965] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 09/25/2017] [Indexed: 01/02/2023] Open
Abstract
Enzymes containing the FIC (filamentation induced by cyclic AMP) domain catalyze post-translational modifications of target proteins. In bacteria the activity of some Fic proteins resembles classical toxin–antitoxin (TA) systems. An excess of toxin over neutralizing antitoxin can enable bacteria to survive some stress conditions by slowing metabolic processes and promoting dormancy. The cell can return to normal growth when sufficient antitoxin is present to block toxin activity. Fic genes of the human and animal pathogen Campylobacter fetus are significantly associated with just one subspecies, which is specifically adapted to the urogenital tract. Here, we demonstrate that the fic genes of virulent isolate C. fetus subsp. venerealis 84-112 form multiple TA systems. Expression of the toxins in Escherichia coli caused filamentation and growth inhibition phenotypes reversible by concomitant antitoxin expression. Key active site residues involved in adenylylation by Fic proteins are conserved in Fic1, Fic3 and Fic4, but degenerated in Fic2. We show that both Fic3 and the non-canonical Fic2 disrupt assembly and function of E. coli ribosomes when expressed independently of a trans-acting antitoxin. Toxicity of the Fic proteins is controlled by different mechanisms. The first involves intramolecular regulation by an inhibitory helix typical for Fic proteins. The second is an unusual neutralization by heterologous Fic–Fic protein interactions. Moreover, a small interacting antitoxin called Fic inhibitory protein 3, which appears unrelated to known Fic antitoxins, has the novel capacity to bind and neutralize Fic toxins encoded in cis and at distant sites. These findings reveal a remarkable system of functional crosstalk occurring between Fic proteins expressed from chromosomal and extrachromosomal modules. Conservation of fic genes in other bacteria that either inhabit or establish pathology in the urogenital tract of humans and animals underscores the significance of these factors for niche-specific adaptation and virulence.
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Affiliation(s)
- Hanna Sprenger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,Institute of Pathology, Medical University of Graz, Graz, Austria.,Division of Gastroenterology and Hepatology, Medical University of Graz, Graz, Austria
| | - Sabine Kienesberger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,Institute of Pathology, Medical University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Brigitte Pertschy
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Lisa Pöltl
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Bettina Konrad
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Priya Bhutada
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Dina Vorkapic
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Denise Atzmüller
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Florian Feist
- Vehicle Safety Institute, Graz University of Technology, Graz, Austria
| | - Christoph Högenauer
- Division of Gastroenterology and Hepatology, Medical University of Graz, Graz, Austria
| | - Gregor Gorkiewicz
- Institute of Pathology, Medical University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Ellen L Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
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20
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Lorenzo-Díaz F, Fernández-López C, Lurz R, Bravo A, Espinosa M. Crosstalk between vertical and horizontal gene transfer: plasmid replication control by a conjugative relaxase. Nucleic Acids Res 2017; 45:7774-7785. [PMID: 28525572 PMCID: PMC5737340 DOI: 10.1093/nar/gkx450] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/25/2017] [Accepted: 05/09/2017] [Indexed: 01/09/2023] Open
Abstract
Horizontal gene transfer is a key process in the evolution of bacteria and also represents a source of genetic variation in eukaryotes. Among elements participating in gene transfer, thousands of small (<10 kb) mobile bacterial plasmids that replicate by the rolling circle mechanism represent a driving force in the spread of antibiotic resistances. In general, these plasmids are built as genetic modules that encode a replicase, an antibiotic-resistance determinant, and a relaxase that participates in their conjugative mobilization. Further, they control their relatively high copy number (∼30 copies per genome equivalent) by antisense RNAs alone or combined with a repressor protein. We report here that the MobM conjugative relaxase encoded by the promiscuous plasmid pMV158 participates in regulation of the plasmid copy number by transcriptional repression of the antisense RNA, thus increasing the number of plasmid molecules ready to be horizontally transferred (mobilization) and/or vertically inherited (replication). This type of crosstalk between genetic modules involved in vertical and horizontal gene flow has not been reported before.
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MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Binding Sites
- Conjugation, Genetic
- DNA Copy Number Variations
- DNA Replication
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Superhelical/chemistry
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- Drug Resistance, Bacterial/genetics
- Endodeoxyribonucleases/genetics
- Endodeoxyribonucleases/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Evolution, Molecular
- Gene Flow
- Gene Transfer, Horizontal
- Microscopy, Electron
- Models, Biological
- Plasmids/genetics
- Promoter Regions, Genetic
- Replicon
- Streptococcus pneumoniae/genetics
- Streptococcus pneumoniae/metabolism
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna. Av. Astrofísico Francisco Sánchez s/n, 38071 Santa Cruz de Tenerife, Spain
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain
| | - Cris Fernández-López
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Rudi Lurz
- Max-Plank Institut für molekulare Genetik, Ihnestrasse 63-73, D-14195 Berlin, Germany
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
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21
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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.
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22
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Abstract
Type IV coupling proteins (T4CPs) are essential constituents of most type IV secretion systems (T4SSs), and probably the most intriguing component in terms of their evolutionary origin and functional role. Coupling proteins have coevolved with their cognate secretion system and translocated substrates. They are present in all conjugative systems, leading to the suggestion that they play a specific role in DNA transfer. However, they are also part of many T4SSs involved in bacterial virulence, where they are required for protein translocation, with no apparent involvement in DNA secretion. Their name reflects genetic and biochemical evidence of a connecting role between the substrate and the T4SS, thus probably playing a major role in substrate recruitment. Increasing evidence supports also a role in signal transmission leading to activation of secretion. Most studies have addressed conjugative coupling proteins of the VirD4-like protein family. Their conserved features include a nucleotide-binding domain, essential for substrate translocation, a C-terminal domain involved in substrate interactions, and a transmembrane domain anchoring them to the inner membrane, which is an important regulator of protein function. Purified soluble deletion mutants display ATP hydrolysis activity and unspecific DNA binding. Elucidation of the 3D structure of the soluble deletion mutant of the conjugative coupling protein TrwB, TrwBΔN70, provided the basis for further mutagenesis studies rendering interesting insights into the structure-function of these proteins. Their key role as couplers between substrate and transporter provides biotechnological potential as targets for anti-virulence strategies, as well as for customization of substrate delivery through heterologous secretion systems.
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Affiliation(s)
- Matxalen Llosa
- Departamento de Biología Molecular, Universidad de Cantabria (UC), and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), UC-CSIC-SODERCAN, C/Albert Einstein 22, 39011, Santander, Spain.
| | - Itziar Alkorta
- Departamento de Bioquímica y Biología Molecular (UPV/EHU), Instituto Biofisika (UPV/EHU, CSIC), Barrio Sarriena S/N, 48940, Leioa, Spain
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Gibert M, Paytubi S, Beltrán S, Juárez A, Balsalobre C, Madrid C. Growth phase-dependent control of R27 conjugation is mediated by the interplay between the plasmid-encoded regulatory circuit TrhR/TrhY-HtdA and the cAMP regulon. Environ Microbiol 2016; 18:5277-5287. [PMID: 27768816 DOI: 10.1111/1462-2920.13579] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 10/14/2016] [Indexed: 01/06/2023]
Abstract
Plasmids of the incompatibility group HI1 (IncHI1) have been isolated from several Gram-negative pathogens and are associated with the spread of multidrug resistance. Their conjugation is tightly regulated and it is inhibited at temperatures higher than 30°C, indicating that conjugation occurs outside warm-blooded hosts. Using R27, the prototype of IncHI1 plasmids, we report that plasmid transfer efficiency in E. coli strongly depends on the physiological state of the donor cells. Conjugation frequency is high when cells are actively growing, dropping sharply when cells enter the stationary phase of growth. Accordingly, our transcriptomic assays show significant downregulation of numerous R27 genes during the stationary phase, including several tra (transfer) genes. Growth phase-dependent regulation of tra genes transcription is independent of H-NS, a silencer of horizontal gene transfer, and ppGpp and RpoS, regulators of the stationary phase, but highly dependent on the plasmid-encoded regulatory circuit TrhR/TrhY-HtdA. The metabolic sensor cAMP, whose synthesis is chromosomally encoded, is also involved in the growth phase regulation of R27 conjugation by modulating htdA expression. Our data suggest that the involvement of regulators encoded by both chromosome and plasmid are required for efficient physiological control of IncHI1 plasmid conjugation.
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Affiliation(s)
- Marta Gibert
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Sonia Paytubi
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Sergi Beltrán
- Centre Nacional d'Anàlisi Genòmica (CNAG), Parc Científic de Barcelona, Baldiri Reixac 4, Barcelona, 08028, Spain
| | - Antonio Juárez
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.,Institut de Bioenginyeria de Catalunya (IBEC), Parc Científic de Barcelona, Baldiri Reixac 10, Barcelona, 08028, Spain
| | - Carlos Balsalobre
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Cristina Madrid
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
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