1
|
Urbanowicz P, Izdebski R, Biedrzycka M, Gniadkowski M. VIM-type metallo-β-lactamase (MBL)-encoding genomic islands in Pseudomonas spp. in Poland: predominance of clc-like integrative and conjugative elements (ICEs). J Antimicrob Chemother 2024; 79:1030-1037. [PMID: 38488311 DOI: 10.1093/jac/dkae068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/23/2024] [Indexed: 05/03/2024] Open
Abstract
OBJECTIVES To characterize VIM-type metallo-β-lactamase (MBL)-encoding genomic islands (GIs) in Pseudomonas aeruginosa and P. putida group isolates from Polish hospitals from 2001-2015/16. METHODS Twelve P. aeruginosa and 20 P. putida group isolates producing VIM-like MBLs were selected from a large collection of these based on epidemiological and typing data. The organisms represented all major epidemic genotypes of these species spread in Poland with chromosomally located blaVIM gene-carrying integrons. The previously determined short-read sequences were complemented by long-read sequencing in this study. The comparative structural analysis of the GIs used a variety of bioinformatic tools. RESULTS Thirty different GIs with blaVIM integrons were identified in the 32 isolates, of which 24 GIs from 26 isolates were integrative and conjugative elements (ICEs) of the clc family. These in turn were dominated by 21 variants of the GI2/ICE6441 subfamily with a total of 19 VIM integrons, each inserted in the same position within the ICE's Tn21-like transposon Tn4380. The three other ICEs formed a novel ICE6705 subfamily, lacking Tn4380 and having different VIM integrons located in another site of the elements. The remaining six non-ICE GIs represented miscellaneous structures. The presence of various integrons in the same ICE sublineage, and of the same integron in different GIs, indicated circulation and recombination of the integron-carrying genetic platforms across Pseudomonas species/genotypes. CONCLUSIONS Despite the general diversity of the blaVIM-carrying GIs in Pseudomonas spp. in Poland, a clear predominance of broadly spread and rapidly evolving clc-type ICEs was documented, confirming their significant role in antimicrobial resistance epidemiology.
Collapse
Affiliation(s)
- P Urbanowicz
- Department of Molecular Microbiology, National Medicines Institute, Chełmska 30/34, Warsaw 00-725, Poland
| | - R Izdebski
- Department of Molecular Microbiology, National Medicines Institute, Chełmska 30/34, Warsaw 00-725, Poland
| | - M Biedrzycka
- Department of Molecular Microbiology, National Medicines Institute, Chełmska 30/34, Warsaw 00-725, Poland
| | - M Gniadkowski
- Department of Molecular Microbiology, National Medicines Institute, Chełmska 30/34, Warsaw 00-725, Poland
| |
Collapse
|
2
|
Benigno V, Carraro N, Sarton-Lohéac G, Romano-Bertrand S, Blanc DS, van der Meer JR. Diversity and evolution of an abundant ICE clc family of integrative and conjugative elements in Pseudomonas aeruginosa. mSphere 2023; 8:e0051723. [PMID: 37902330 PMCID: PMC10732049 DOI: 10.1128/msphere.00517-23] [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: 09/08/2023] [Accepted: 09/24/2023] [Indexed: 10/31/2023] Open
Abstract
IMPORTANCE Microbial populations swiftly adapt to changing environments through horizontal gene transfer. While the mechanisms of gene transfer are well known, the impact of environmental conditions on the selection of transferred gene functions remains less clear. We investigated ICEs, specifically the ICEclc-type, in Pseudomonas aeruginosa clinical isolates. Our findings revealed co-evolution between ICEs and their hosts, with ICE transfers occurring within strains. Gene functions carried by ICEs are positively selected, including potential virulence factors and heavy metal resistance. Comparison to publicly available P. aeruginosa genomes unveiled widespread antibiotic-resistance determinants within ICEclc clades. Thus, the ubiquitous ICEclc family significantly contributes to P. aeruginosa's adaptation and fitness in diverse environments.
Collapse
Affiliation(s)
- Valentina Benigno
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Carraro
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Garance Sarton-Lohéac
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Sara Romano-Bertrand
- Hydrosciences Montpellier, IRD, CNRS, University of Montpellier, Hospital Hygiene and Infection Control Team, University Hospital of Montpellier, Montpellier, France
| | - Dominique S. Blanc
- Prevention and Infection Control Unit, Infectious Diseases Service, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | | |
Collapse
|
3
|
Ivanovski I, Zylstra GJ. Genetic and Functional Characterization of a Salicylate 1-monooxygenase Located on an Integrative and Conjugative Element (ICE) in Pseudomonas stutzeri AJR13. J Microbiol 2023; 61:1025-1032. [PMID: 38100000 DOI: 10.1007/s12275-023-00093-x] [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: 06/29/2023] [Revised: 11/02/2023] [Accepted: 11/05/2023] [Indexed: 01/11/2024]
Abstract
Pseudomonas stutzeri strain AJR13 was isolated for growth on the related compounds biphenyl (BPH) and diphenylmethane (DPM). The BPH and DPM degradative pathway genes are present on an integrative and conjugative element (ICE) in the chromosome. Examination of the genome sequence of AJR13 revealed a gene encoding a salicylate 1-monooxygenase (salA) associated with the ICE even though AJR13 did not grow on salicylate. Transfer of the ICE to the well-studied Pseudomonas putida KT2440 resulted in a KT2440 strain that could grow on salicylate. Knockout mutagenesis of the salA gene on the ICE in KT2440 eliminated the ability to grow on salicylate. Complementation of the knockout with the cloned salA gene restored growth on salicylate. Transfer of the cloned salA gene under control of the lac promoter to KT2440 resulted in a strain that could grow on salicylate. Heterologous expression of the salA gene in E. coli BL21 DE3 resulted in the production of catechol from salicylate, confirming that it is indeed a salicylate 1-monooxygenase. Interestingly, transfer of the cloned salA gene under control of the lac promoter to AJR13 resulted in a strain that could now grow on salicylate, suggesting that gene expression for the downstream catechol pathway is intact.
Collapse
Affiliation(s)
- Igor Ivanovski
- Department of Biology, St. Joseph's University, Patchogue, NY, 11772, USA.
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ, 08901, USA.
| | - Gerben J Zylstra
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| |
Collapse
|
4
|
Iasakov T. Evolution End Classification of tfd Gene Clusters Mediating Bacterial Degradation of 2,4-Dichlorophenoxyacetic Acid (2,4-D). Int J Mol Sci 2023; 24:14370. [PMID: 37762674 PMCID: PMC10531765 DOI: 10.3390/ijms241814370] [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: 07/30/2023] [Revised: 09/11/2023] [Accepted: 09/16/2023] [Indexed: 09/29/2023] Open
Abstract
The tfd (tfdI and tfdII) are gene clusters originally discovered in plasmid pJP4 which are involved in the bacterial degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) via the ortho-cleavage pathway of chlorinated catechols. They share this activity, with respect to substituted catechols, with clusters tcb and clc. Although great effort has been devoted over nearly forty years to exploring the structural diversity of these clusters, their evolution has been poorly resolved to date, and their classification is clearly obsolete. Employing comparative genomic and phylogenetic approaches has revealed that all tfd clusters can be classified as one of four different types. The following four-type classification and new nomenclature are proposed: tfdI, tfdII, tfdIII and tfdIV(A,B,C). Horizontal gene transfer between Burkholderiales and Sphingomonadales provides phenomenal linkage between tfdI, tfdII, tfdIII and tfdIV type clusters and their mosaic nature. It is hypothesized that the evolution of tfd gene clusters proceeded within first (tcb, clc and tfdI), second (tfdII and tfdIII) and third (tfdIV(A,B,C)) evolutionary lineages, in each of which, the genes were clustered in specific combinations. Their clustering is discussed through the prism of hot spots and driving forces of various models, theories, and hypotheses of cluster and operon formation. Two hypotheses about series of gene deletions and displacements are also proposed to explain the structural variations across members of clusters tfdII and tfdIII, respectively. Taking everything into account, these findings reconstruct the phylogeny of tfd clusters, have delineated their evolutionary trajectories, and allow the contribution of various evolutionary processes to be assessed.
Collapse
Affiliation(s)
- Timur Iasakov
- Ufa Institute of Biology, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 69, 450054 Ufa, Russia
| |
Collapse
|
5
|
Chang MX, Zhang J, Zhang JF, Ding XM, Lu Y, Zhang J, Li R, Jiang HX. Formation, Transmission, and Dynamic Evolution of a Multidrug-Resistant Chromosomally Integrated Plasmid in Salmonella Spp. Front Microbiol 2022; 13:846954. [PMID: 35464949 PMCID: PMC9019673 DOI: 10.3389/fmicb.2022.846954] [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: 12/31/2021] [Accepted: 02/17/2022] [Indexed: 11/24/2022] Open
Abstract
IncHI2 plasmids, possessing high flexibility and genetic plasticity, play a vital role in the acquisition and transmission of resistance determinants. Polymorphic mobile genetic elements (MGEs) generated by a chromosomally integrated IncHI2 plasmid in an individual Salmonella isolate have not yet been detected, and the mechanisms of the formation, excision, and dynamic evolution of a multidrug-resistant chromosomally integrated plasmid (MRCP) have remained obscure. Herein, we identified a 260-kb blaCTX–M–55-qnrS1-bearing IncHI2 plasmid within a Salmonella Muenster strain. Plenty of heterogeneous MGEs (new Escherichia coli chromosomally integrated plasmid or circular plasmids with different profiles) were yielded when this MRCP was conjugated into E. coli J53 with a transfer frequency of 10–4–10–5 transconjugants per donor. A bioinformatic analysis indicated that replicative transposition and homologous recombination of IS26 elements were particularly active, and the truncated Tn1721 also played a vital role in the formation of MRCP offspring. More importantly, when released from the chromosome, MRCP could capture and co-transfer adjacent chromosomal segments to form larger plasmid progeny than itself. Stability and growth kinetics assays showed that the biological characteristics of MRCP progeny were differentiated. This study provides an insight into a flexible existence of MRCP. The conversion between vertical and horizontal transmission endowed MRCP with genetic stability as a chromosomal coding structure and transferability as extra-chromosomal elements. This alternation may accelerate the acquisition and persistence of antibiotic resistance of clinical pathogens and enhance their ability to respond to adverse environments, which poses a great challenge to the traditional antibiotic treatment.
Collapse
Affiliation(s)
- Man-Xia Chang
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Jing Zhang
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Jin-Fei Zhang
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Xiao-Min Ding
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Yang Lu
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Jie Zhang
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Ruichao Li
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Hong-Xia Jiang
- Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| |
Collapse
|
6
|
Cai H, Zhu Y, Hu D, Li Y, Leptihn S, Loh B, Hua X, Yu Y. Co-harboring of Novel bla KPC-2 Plasmid and Integrative and Conjugative Element Carrying Tn 6203 in Multidrug-Resistant Pseudomonas aeruginosa. Front Microbiol 2021; 12:674974. [PMID: 34290680 PMCID: PMC8287167 DOI: 10.3389/fmicb.2021.674974] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/31/2021] [Indexed: 11/18/2022] Open
Abstract
Many strains of the opportunistic pathogen Pseudomonas aeruginosa have acquired resistance to multiple antibiotics. Carbapenem-resistant P. aeruginosa poses a global healthcare problem due to limited therapeutic options for the treatment of infections. Plasmids and integrative and conjugative elements (ICEs) are the major vectors of antibiotic-resistance gene transfer. In our study, four carbapenem-resistant strains of P. aeruginosa were isolated from the same patient in a tertiary referral hospital in China, one of these was resistant to gentamicin and tobramycin. In this strain P33, we observed a non-transferable plasmid, pP33-2, carrying a novel blaKPC−2 gene segment (ISKpn27-blaKPC−2-ISKpn6-korC-ORF-klcA-IS26), which we concluded to have been formed by IS26-mediated gene cluster translocation. In addition, by comparing the chromosomes of the P. aeruginosa strains that belong to the same sequence type, we identified an ICE, ICEP33, adjacent to a prophage. The attL site of ICEP33 is identical to the terminal part of the attR site of the prophage. The ICEP33 element contains the transposon Tn6203, which encodes antibiotic and metal resistance genes. The insertion of ICEP33 in the chromosome mediates resistance to multiple antibiotics. Our study contributes to the understanding of the acquisition of antibiotic resistance in P. aeruginosa facilitated by mobile genetic elements.
Collapse
Affiliation(s)
- Heng Cai
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yiwei Zhu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Dandan Hu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yue Li
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Sebastian Leptihn
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Zhejiang University-University of Edinburgh Institute, Zhejiang University, Haining, China
| | - Belinda Loh
- Zhejiang University-University of Edinburgh Institute, Zhejiang University, Haining, China
| | - Xiaoting Hua
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yunsong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
7
|
IHF stabilizes pathogenicity island I of uropathogenic Escherichia coli strain 536 by attenuating integrase I promoter activity. Sci Rep 2020; 10:9397. [PMID: 32523028 PMCID: PMC7286903 DOI: 10.1038/s41598-020-66215-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/12/2020] [Indexed: 11/19/2022] Open
Abstract
Pathogenicity islands (PAIs) represent horizontally acquired chromosomal regions and encode their cognate integrase, which mediates chromosomal integration and excision of the island. These site-specific recombination reactions have to be tightly controlled to maintain genomic stability, and their directionality depends on accessory proteins. The integration host factor (IHF) and the factor for inversion stimulation (Fis) are often involved in recombinogenic complex formation and controlling the directionality of the recombination reaction. We investigated the role of the accessory host factors IHF and Fis in controlling the stability of six PAIs in uropathogenic Escherichia coli strain 536. By comparing the loss of individual PAIs in the presence or absence of IHF or Fis, we showed that IHF specifically stabilized PAI I536 and that in particular the IHFB subunit seems to be important for this function. We employed complex genetic studies to address the role of IHF in PAI I536-encoded integrase (IntI) expression. Based on different YFP-reporter constructs and electrophoretic mobility shift assays we demonstrated that IntI acts a strong repressor of its own synthesis, and that IHF binding to the intI promoter region reduces the probability of intI promoter activation. Our results extend the current knowledge of the role of IHF in controlling directionality of site specific recombination reactions and thus PAI stability.
Collapse
|
8
|
Emergence of a Plasmid-Encoded Resistance-Nodulation-Division Efflux Pump Conferring Resistance to Multiple Drugs, Including Tigecycline, in Klebsiella pneumoniae. mBio 2020; 11:mBio.02930-19. [PMID: 32127452 PMCID: PMC7064769 DOI: 10.1128/mbio.02930-19] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In an era of increasing concerns about antimicrobial resistance, tigecycline is likely to have a critically important role in the treatment of carbapenem-resistant Enterobacteriaceae, the most problematic pathogens in human clinical settings—especially carbapenem-resistant K.pneumoniae. Here, we identified a new plasmid-borne RND-type tigecycline resistance determinant, TMexCD1-TOprJ1, which is widespread among K. pneumoniae isolates from food animals. tmexCD1-toprJ1 appears to have originated from the chromosome of a Pseudomonas species and may have been transferred onto plasmids by adjacent site-specific integrases. Although tmexCD1-toprJ1 still appears to be rare in human clinical isolates, considering the transferability of the tmexCD1-toprJ1 gene cluster and the broad substrate spectrum of TMexCD1-TOprJ1, further dissemination of this mobile tigecycline resistance determinant is possible. Therefore, from a “One Health” perspective, measures are urgently needed to monitor and control its further spread. The current low prevalence in human clinical isolates provides a precious time window to design and implement measures to tackle this. Transporters belonging to the chromosomally encoded resistance-nodulation-division (RND) superfamily mediate multidrug resistance in Gram-negative bacteria. However, the cotransfer of large gene clusters encoding RND-type pumps from the chromosome to a plasmid appears infrequent, and no plasmid-mediated RND efflux pump gene cluster has yet been found to confer resistance to tigecycline. Here, we identified a novel RND efflux pump gene cluster, designated tmexCD1-toprJ1, on plasmids from five pandrug-resistant Klebsiella pneumoniae isolates of animal origin. TMexCD1-TOprJ1 increased (by 4- to 32-fold) the MICs of tetracyclines (including tigecycline and eravacycline), quinolones, cephalosporins, and aminoglycosides for K.pneumoniae, Escherichia coli, and Salmonella. TMexCD1-TOprJ1 is closely related (64.5% to 77.8% amino acid identity) to the MexCD-OprJ efflux pump encoded on the chromosome of Pseudomonas aeruginosa. In an IncFIA plasmid, pHNAH8I, the tmexCD1-toprJ1 gene cluster lies adjacent to two genes encoding site-specific integrases, which may have been responsible for its acquisition. Expression of TMexCD1-TOprJ1 in E. coli resulted in increased tigecycline efflux and in K. pneumoniae negated the efficacy of tigecycline in an in vivo infection model. Expression of TMexCD1-TOprJ1 reduced the growth of E. coli and Salmonella but not K. pneumoniae. tmexCD1-toprJ1-positive Enterobacteriaceae isolates were rare in humans (0.08%) but more common in chicken fecal (14.3%) and retail meat (3.4%) samples. Plasmid-borne tmexCD1-toprJ1-like gene clusters were identified in sequences in GenBank from Enterobacteriaceae and Pseudomonas strains from multiple continents. The possibility of further global dissemination of the tmexCD1-toprJ1 gene cluster and its analogues in Enterobacteriaceae via plasmids may be an important consideration for public health planning.
Collapse
|
9
|
Takano S, Fukuda K, Koto A, Miyazaki R. A novel system of bacterial cell division arrest implicated in horizontal transmission of an integrative and conjugative element. PLoS Genet 2019; 15:e1008445. [PMID: 31609967 PMCID: PMC6812849 DOI: 10.1371/journal.pgen.1008445] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/24/2019] [Accepted: 09/24/2019] [Indexed: 11/19/2022] Open
Abstract
Integrative and conjugative elements (ICEs) are widespread mobile DNA elements in the prokaryotic world. ICEs are usually retained within the bacterial chromosome, but can be excised and transferred from a donor to a new recipient cell, even of another species. Horizontal transmission of ICEclc, a prevalent ICE in proteobacteria, only occurs from developed specialized transfer competent (tc) cells in the donor population. tc cells become entirely dedicated to the ICE transmission at the cost of cell proliferation. The cell growth impairment is mediated by two ICEclc located genes, parA and shi, but the mechanistic and dynamic details of this process are unknown. To better understand the function of ParA and Shi, we followed their intracellular behavior from fluorescent protein fusions, and studied host cell division at single-cell level. Superresolution imaging revealed that ParA-mCherry colocalized with the host nucleoid while Shi-GFP was enriched at the membrane during the growth impairment. Despite being enriched at different cellular locations, the two proteins showed in vivo interactions, and mutations in the Walker A motif of ParA dislocalized both ParA and Shi. In addition, ParA mutations in the ATPase motif abolished the growth arrest on the host cell. Time-lapse microscopy revealed that ParA and Shi initially delay cell division, suggesting an extension of the S phase of cells, but eventually completely inhibit cell elongation. The parA-shi locus is highly conserved in other ICEclc-related elements, and expressing ParA-Shi from ICEclc in other proteobacterial species caused similar growth arrest, suggesting that the system functions similarly across hosts. The results of our study provide mechanistic insight into the novel and unique system on ICEs and help to understand such epistatic interaction between ICE genes and host physiology that entails efficient horizontal gene transfer.
Collapse
Affiliation(s)
- Sotaro Takano
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Kohei Fukuda
- Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, Hamamatsu, Japan
| | - Akiko Koto
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Computational Bio Big Data Open Innovation Laboratory (CBBD-OIL), AIST, Tokyo, Japan
| | - Ryo Miyazaki
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Computational Bio Big Data Open Innovation Laboratory (CBBD-OIL), AIST, Tokyo, Japan
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
- * E-mail:
| |
Collapse
|
10
|
Sub-Inhibitory concentrations of SOS-Response inducing antibiotics stimulate integrase expression and excision of pathogenicity islands in uropathogenic Escherichia coli strain 536. Int J Med Microbiol 2019; 310:151361. [PMID: 31640923 DOI: 10.1016/j.ijmm.2019.151361] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/26/2019] [Accepted: 09/29/2019] [Indexed: 01/24/2023] Open
Abstract
Urinary tract infections are one of the most common bacterial infections and a major public health problem. The predominant causative agents are uropathogenic Escherichia coli. These strains differ from commensal E. coli by the presence of additional horizontally acquired chromosomal material, so-called pathogenicity islands, which encode traits that promote efficient bacterial colonization of the urinary tract. Uropathogenic model strain E. coli 536 possesses six archetypal pathogenicity islands. Bacteriophage-like integrases encoded by each pathogenicity island contribute to island instability. To learn more about the stability of these six islands and factors controlling their stability we constructed two chromosomal reporter systems for the measurement of island loss, as well as for the measurement of the promoter activity of the six island-associated integrase genes at the population level. We used these reporter gene modules to analyze the role of SOS response in island instability. Tests with subinhibitory concentrations of different antibiotics, including many drugs commonly used for the treatment of urinary tract infection, indicated that only SOS response-inducing antibiotics led to an increased loss of islands which was always associated with an increase in the bacterial subpopulations showing high integrase promoter activity. This suggests that island excision correlates with the expression of the cognate integrase. Our reporter modules are valuable tools to investigate the impact of various growth conditions on genome plasticity. Furthermore, a better understanding of the conditions, which affect bacterial integrase expression may open ways to specifically manipulate the genome content of bacterial pathogens by increasing pathogenicity island deletion rates in infecting or colonizing bacteria, thus leading to the attenuation of bacterial pathogens.
Collapse
|
11
|
Verdonk CJ, Sullivan JT, Williman KM, Nicholson L, Bastholm TR, Hynes MF, Ronson CW, Bond CS, Ramsay JP. Delineation of the integrase-attachment and origin-of-transfer regions of the symbiosis island ICEMlSymR7A. Plasmid 2019; 104:102416. [DOI: 10.1016/j.plasmid.2019.102416] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/12/2019] [Accepted: 05/07/2019] [Indexed: 12/12/2022]
|
12
|
Nonaka L, Yamamoto T, Maruyama F, Hirose Y, Onishi Y, Kobayashi T, Suzuki S, Nomura N, Masuda M, Yano H. Interplay of a non-conjugative integrative element and a conjugative plasmid in the spread of antibiotic resistance via suicidal plasmid transfer from an aquaculture Vibrio isolate. PLoS One 2018; 13:e0198613. [PMID: 29879198 PMCID: PMC5991714 DOI: 10.1371/journal.pone.0198613] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 05/22/2018] [Indexed: 12/01/2022] Open
Abstract
The capture of antimicrobial resistance genes (ARGs) by mobile genetic elements (MGEs) plays a critical role in resistance acquisition for human-associated bacteria. Although aquaculture environments are recognized as important reservoirs of ARGs, intra- and intercellular mobility of MGEs discovered in marine organisms is poorly characterized. Here, we show a new pattern of interspecies ARGs transfer involving a 'non-conjugative' integrative element. To identify active MGEs in a Vibrio ponticus isolate, we conducted whole-genome sequencing of a transconjugant obtained by mating between Escherichia coli and Vibrio ponticus. This revealed integration of a plasmid (designated pSEA1) into the chromosome, consisting of a self-transmissible plasmid backbone of the MOBH group, ARGs, and a 13.8-kb integrative element Tn6283. Molecular genetics analysis suggested a two-step gene transfer model. First, Tn6283 integrates into the recipient chromosome during suicidal plasmid transfer, followed by homologous recombination between the Tn6283 copy in the chromosome and that in the newly transferred pSEA1. Tn6283 is unusual among integrative elements in that it apparently does not encode transfer function and its excision barely generates unoccupied donor sites. Thus, its movement is analogous to the transposition of insertion sequences rather than to that of canonical integrative and conjugative elements. Overall, this study reveals the presence of a previously unrecognized type of MGE in a marine organism, highlighting diversity in the mode of interspecies gene transfer.
Collapse
Affiliation(s)
- Lisa Nonaka
- Department of Microbiology, Dokkyo Medical University School of Medicine, Mibu, Tochigi, Japan
| | - Tatsuya Yamamoto
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
| | | | - Yuu Hirose
- Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku, Toyohashi, Aichi, Japan
| | - Yuki Onishi
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Ehime, Japan
| | | | - Satoru Suzuki
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Ehime, Japan
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Michiaki Masuda
- Department of Microbiology, Dokkyo Medical University School of Medicine, Mibu, Tochigi, Japan
| | - Hirokazu Yano
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
| |
Collapse
|
13
|
Delavat F, Miyazaki R, Carraro N, Pradervand N, van der Meer JR. The hidden life of integrative and conjugative elements. FEMS Microbiol Rev 2017; 41:512-537. [PMID: 28369623 PMCID: PMC5812530 DOI: 10.1093/femsre/fux008] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/20/2017] [Indexed: 01/01/2023] Open
Abstract
Integrative and conjugative elements (ICEs) are widespread mobile DNA that transmit both vertically, in a host-integrated state, and horizontally, through excision and transfer to new recipients. Different families of ICEs have been discovered with more or less restricted host ranges, which operate by similar mechanisms but differ in regulatory networks, evolutionary origin and the types of variable genes they contribute to the host. Based on reviewing recent experimental data, we propose a general model of ICE life style that explains the transition between vertical and horizontal transmission as a result of a bistable decision in the ICE-host partnership. In the large majority of cells, the ICE remains silent and integrated, but hidden at low to very low frequencies in the population specialized host cells appear in which the ICE starts its process of horizontal transmission. This bistable process leads to host cell differentiation, ICE excision and transfer, when suitable recipients are present. The ratio of ICE bistability (i.e. ratio of horizontal to vertical transmission) is the outcome of a balance between fitness costs imposed by the ICE horizontal transmission process on the host cell, and selection for ICE distribution (i.e. ICE 'fitness'). From this emerges a picture of ICEs as elements that have adapted to a mostly confined life style within their host, but with a very effective and dynamic transfer from a subpopulation of dedicated cells.
Collapse
Affiliation(s)
- François Delavat
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne Switzerland
| | - Ryo Miyazaki
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8566, Japan
| | - Nicolas Carraro
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne Switzerland
| | - Nicolas Pradervand
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne Switzerland
| | | |
Collapse
|
14
|
Highly variable individual donor cell fates characterize robust horizontal gene transfer of an integrative and conjugative element. Proc Natl Acad Sci U S A 2016; 113:E3375-83. [PMID: 27247406 DOI: 10.1073/pnas.1604479113] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Horizontal gene transfer is an important evolutionary mechanism for bacterial adaptation. However, given the typical low transfer frequencies in a bacterial population, little is known about the fate and interplay of donor cells and the mobilized DNA during transfer. Here we study transfer of an integrative and conjugative element (ICE) among individual live bacterial cells. ICEs are widely distributed mobile DNA elements that are different than plasmids because they reside silent in the host chromosome and are maintained through vertical descent. Occasionally, ICEs become active, excise, and transmit their DNA to a new recipient, where it is reintegrated. We develop a fluorescent tool to differentiate excision, transfer, and reintegration of a model ICE named ICEclc (for carrying the clc genes for chlorocatechol metabolism) among single Pseudomonas cells by using time-lapse microscopy. We find that ICEclc activation is initiated in stationary phase cells, but excision and transfer predominantly occur only when such cells have been presented with new nutrients. Donors with activated ICE develop a number of different states, characterized by reduced cell division rates or growth arrest, persistence, or lysis, concomitant with ICE excision, and likely, ICE loss or replication. The donor cell state transitions can be described by using a stochastic model, which predicts that ICE fitness is optimal at low initiation rates in stationary phase. Despite highly variable donor cell fates, ICE transfer is remarkably robust overall, with 75% success after excision. Our results help to better understand ICE behavior and shed a new light on bacterial cellular differentiation during horizontal gene transfer.
Collapse
|
15
|
Vanga BR, Ramakrishnan P, Butler RC, Toth IK, Ronson CW, Jacobs JME, Pitman AR. Mobilization of horizontally acquired island 2 is induced in planta in the phytopathogen Pectobacterium atrosepticum SCRI1043 and involves the putative relaxase ECA0613 and quorum sensing. Environ Microbiol 2015; 17:4730-44. [PMID: 26271942 DOI: 10.1111/1462-2920.13024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 01/30/2023]
Abstract
Integrative and conjugative elements (ICEs) contribute to the rapid evolution of bacterial pathogens via horizontal gene transfer of virulence determinants. ICEs have common mechanisms for transmission, yet the cues triggering this process under natural environmental or physiological conditions are largely unknown. In this study, mobilization of the putative ICE horizontally acquired island 2 (HAI2), present in the chromosome of the phytopathogen Pectobacterium atrosepticum SCRI1043, was examined during infection of the host plant potato. Under these conditions, mobilization of HAI2 increased markedly compared with in vitro cultures. In planta-induced mobilization of HAI2 was regulated by quorum sensing and involved the putative ICE-encoded relaxase ECA0613. Disruption of ECA0613 also reduced transcription of genes involved in production of coronafacic acid (Cfa), the major virulence factor harboured on HAI2, whereas their expression was unaffected in the quorum-sensing (expI) mutant. Thus, suppression of cfa gene expression was not regulated by the mobilization of the ICE per se, but was due directly to inactivation of the relaxase. The identification of genetic factors associated solely with in planta mobilization of an ICE demonstrates that this process is highly adapted to the natural environment of the bacterial host and can influence the expression of virulence determinants.
Collapse
Affiliation(s)
- Bhanupratap R Vanga
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand.,Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Pavithra Ramakrishnan
- Bioprotection Research Centre, Lincoln University, PO Box 84, Canterbury, 7647, New Zealand
| | - Ruth C Butler
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand
| | - Ian K Toth
- James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Clive W Ronson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Jeanne M E Jacobs
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand.,Bioprotection Research Centre, Lincoln University, PO Box 84, Canterbury, 7647, New Zealand
| | - Andrew R Pitman
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand.,Bioprotection Research Centre, Lincoln University, PO Box 84, Canterbury, 7647, New Zealand
| |
Collapse
|
16
|
Shetty AR, de Gannes V, Obi CC, Lucas S, Lapidus A, Cheng JF, Goodwin LA, Pitluck S, Peters L, Mikhailova N, Teshima H, Han C, Tapia R, Land M, Hauser LJ, Kyrpides N, Ivanova N, Pagani I, Chain PSG, Denef VJ, Woyke T, Hickey WJ. Complete genome sequence of the phenanthrene-degrading soil bacterium Delftia acidovorans Cs1-4. Stand Genomic Sci 2015; 10:55. [PMID: 26380642 PMCID: PMC4572682 DOI: 10.1186/s40793-015-0041-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 07/15/2015] [Indexed: 11/23/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants and microbial biodegradation is an important means of remediation of PAH-contaminated soil. Delftia acidovorans Cs1-4 (formerly Delftia sp. Cs1-4) was isolated by using phenanthrene as the sole carbon source from PAH contaminated soil in Wisconsin. Its full genome sequence was determined to gain insights into a mechanisms underlying biodegradation of PAH. Three genomic libraries were constructed and sequenced: an Illumina GAii shotgun library (916,416,493 reads), a 454 Titanium standard library (770,171 reads) and one paired-end 454 library (average insert size of 8 kb, 508,092 reads). The initial assembly contained 40 contigs in two scaffolds. The 454 Titanium standard data and the 454 paired end data were assembled together and the consensus sequences were computationally shredded into 2 kb overlapping shreds. Illumina sequencing data was assembled, and the consensus sequence was computationally shredded into 1.5 kb overlapping shreds. Gaps between contigs were closed by editing in Consed, by PCR and by Bubble PCR primer walks. A total of 182 additional reactions were needed to close gaps and to raise the quality of the finished sequence. The final assembly is based on 253.3 Mb of 454 draft data (averaging 38.4 X coverage) and 590.2 Mb of Illumina draft data (averaging 89.4 X coverage). The genome of strain Cs1-4 consists of a single circular chromosome of 6,685,842 bp (66.7 %G+C) containing 6,028 predicted genes; 5,931 of these genes were protein-encoding and 4,425 gene products were assigned to a putative function. Genes encoding phenanthrene degradation were localized to a 232 kb genomic island (termed the phn island), which contained near its 3' end a bacteriophage P4-like integrase, an enzyme often associated with chromosomal integration of mobile genetic elements. Other biodegradation pathways reconstructed from the genome sequence included: benzoate (by the acetyl-CoA pathway), styrene, nicotinic acid (by the maleamate pathway) and the pesticides Dicamba and Fenitrothion. Determination of the complete genome sequence of D. acidovorans Cs1-4 has provided new insights the microbial mechanisms of PAH biodegradation that may shape the process in the environment.
Collapse
Affiliation(s)
- Ameesha R. Shetty
- />O.N. Allen Laboratory for Soil Microbiology, Department of Soil Science, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - Vidya de Gannes
- />Department of Food Production, University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Chioma C. Obi
- />Department of Microbiology, University of Lagos, Lagos, Nigeria
| | - Susan Lucas
- />DOE Joint Genome Institute, Walnut Creek, CA USA
| | - Alla Lapidus
- />Algorithmic Biology Lab, St. Petersburg Academic University, St.Petersburg, Russia
| | | | - Lynne A. Goodwin
- />Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM USA
| | | | - Linda Peters
- />DOE Joint Genome Institute, Walnut Creek, CA USA
| | | | - Hazuki Teshima
- />Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM USA
| | - Cliff Han
- />Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM USA
| | - Roxanne Tapia
- />Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM USA
| | - Miriam Land
- />Oak Ridge National Laboratory, Oak Ridge, TN USA
| | | | | | | | | | | | - Vincent J Denef
- />Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI USA
| | - Tanya Woyke
- />DOE Joint Genome Institute, Walnut Creek, CA USA
| | - William J. Hickey
- />O.N. Allen Laboratory for Soil Microbiology, Department of Soil Science, University of Wisconsin-Madison, Madison, WI 53706 USA
| |
Collapse
|
17
|
Fogg PCM, Colloms S, Rosser S, Stark M, Smith MCM. New applications for phage integrases. J Mol Biol 2014; 426:2703-16. [PMID: 24857859 PMCID: PMC4111918 DOI: 10.1016/j.jmb.2014.05.014] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 05/09/2014] [Accepted: 05/16/2014] [Indexed: 11/28/2022]
Abstract
Within the last 25 years, bacteriophage integrases have rapidly risen to prominence as genetic tools for a wide range of applications from basic cloning to genome engineering. Serine integrases such as that from ϕC31 and its relatives have found an especially wide range of applications within diverse micro-organisms right through to multi-cellular eukaryotes. Here, we review the mechanisms of the two major families of integrases, the tyrosine and serine integrases, and the advantages and disadvantages of each type as they are applied in genome engineering and synthetic biology. In particular, we focus on the new areas of metabolic pathway construction and optimization, biocomputing, heterologous expression and multiplexed assembly techniques. Integrases are versatile and efficient tools that can be used in conjunction with the various extant molecular biology tools to streamline the synthetic biology production line. Phage integrases are site-specific recombinases that mediate controlled and precise DNA integration and excision. The serine integrases, such as ϕC31 integrase, can be used for efficient recombination in heterologous hosts as they use short recombination substrates, they are directional and they do not require host factors. Both serine and tyrosine integrases, such as λ integrase, are versatile tools for DNA cloning and assembly in vivo and in vitro. Controlled expression of orthologous serine integrases and their cognate recombination directionality factors can be used to generate living biocomputers. Serine integrases are increasingly being exploited for synthetic biology applications.
Collapse
Affiliation(s)
- Paul C M Fogg
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK
| | - Sean Colloms
- Institute of Molecular Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - Susan Rosser
- School of Biological Sciences, University of Edinburgh, King's Building, Edinburgh EH9 3JR, UK
| | - Marshall Stark
- Institute of Molecular Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - Margaret C M Smith
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
| |
Collapse
|
18
|
Paliwal V, Raju SC, Modak A, Phale PS, Purohit HJ. Pseudomonas putida CSV86: a candidate genome for genetic bioaugmentation. PLoS One 2014; 9:e84000. [PMID: 24475028 PMCID: PMC3901652 DOI: 10.1371/journal.pone.0084000] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 11/11/2013] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas putida CSV86, a plasmid-free strain possessing capability to transfer the naphthalene degradation property, has been explored for its metabolic diversity through genome sequencing. The analysis of draft genome sequence of CSV86 (6.4 Mb) revealed the presence of genes involved in the degradation of naphthalene, salicylate, benzoate, benzylalcohol, p-hydroxybenzoate, phenylacetate and p-hydroxyphenylacetate on the chromosome thus ensuring the stability of the catabolic potential. Moreover, genes involved in the metabolism of phenylpropanoid and homogentisate, as well as heavy metal resistance, were additionally identified. Ability to grow on vanillin, veratraldehyde and ferulic acid, detection of inducible homogentisate dioxygenase and growth on aromatic compounds in the presence of heavy metals like copper, cadmium, cobalt and arsenic confirm in silico observations reflecting the metabolic versatility. In silico analysis revealed the arrangement of genes in the order: tRNAGly, integrase followed by nah operon, supporting earlier hypothesis of existence of a genomic island (GI) for naphthalene degradation. Deciphering the genomic architecture of CSV86 for aromatic degradation pathways and identification of elements responsible for horizontal gene transfer (HGT) suggests that genetic bioaugmentation strategies could be planned using CSV86 for effective bioremediation.
Collapse
Affiliation(s)
- Vasundhara Paliwal
- Environmental Genomics Division, CSIR-National Environmental Engineering Research Institute, Nagpur, India
| | - Sajan C Raju
- MEM-Group, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Arnab Modak
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai, India
| | - Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai, India
| | - Hemant J Purohit
- Environmental Genomics Division, CSIR-National Environmental Engineering Research Institute, Nagpur, India
| |
Collapse
|
19
|
Reinhard F, van der Meer JR. Improved statistical analysis of low abundance phenomena in bimodal bacterial populations. PLoS One 2013; 8:e78288. [PMID: 24205184 PMCID: PMC3813492 DOI: 10.1371/journal.pone.0078288] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 09/10/2013] [Indexed: 01/10/2023] Open
Abstract
Accurate detection of subpopulation size determinations in bimodal populations remains problematic yet it represents a powerful way by which cellular heterogeneity under different environmental conditions can be compared. So far, most studies have relied on qualitative descriptions of population distribution patterns, on population-independent descriptors, or on arbitrary placement of thresholds distinguishing biological ON from OFF states. We found that all these methods fall short of accurately describing small population sizes in bimodal populations. Here we propose a simple, statistics-based method for the analysis of small subpopulation sizes for use in the free software environment R and test this method on real as well as simulated data. Four so-called population splitting methods were designed with different algorithms that can estimate subpopulation sizes from bimodal populations. All four methods proved more precise than previously used methods when analyzing subpopulation sizes of transfer competent cells arising in populations of the bacterium Pseudomonas knackmussii B13. The methods’ resolving powers were further explored by bootstrapping and simulations. Two of the methods were not severely limited by the proportions of subpopulations they could estimate correctly, but the two others only allowed accurate subpopulation quantification when this amounted to less than 25% of the total population. In contrast, only one method was still sufficiently accurate with subpopulations smaller than 1% of the total population. This study proposes a number of rational approximations to quantifying small subpopulations and offers an easy-to-use protocol for their implementation in the open source statistical software environment R.
Collapse
Affiliation(s)
- Friedrich Reinhard
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Jan Roelof van der Meer
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
- * E-mail:
| |
Collapse
|
20
|
A new large-DNA-fragment delivery system based on integrase activity from an integrative and conjugative element. Appl Environ Microbiol 2013; 79:4440-7. [PMID: 23686268 DOI: 10.1128/aem.00711-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
During the past few decades, numerous plasmid vectors have been developed for cloning, gene expression analysis, and genetic engineering. Cloning procedures typically rely on PCR amplification, DNA fragment restriction digestion, recovery, and ligation, but increasingly, procedures are being developed to assemble large synthetic DNAs. In this study, we developed a new gene delivery system using the integrase activity of an integrative and conjugative element (ICE). The advantage of the integrase-based delivery is that it can stably introduce a large DNA fragment (at least 75 kb) into one or more specific sites (the gene for glycine-accepting tRNA) on a target chromosome. Integrase recombination activity in Escherichia coli is kept low by using a synthetic hybrid promoter, which, however, is unleashed in the final target host, forcing the integration of the construct. Upon integration, the system is again silenced. Two variants with different genetic features were produced, one in the form of a cloning vector in E. coli and the other as a mini-transposable element by which large DNA constructs assembled in E. coli can be tagged with the integrase gene. We confirmed that the system could successfully introduce cosmid and bacterial artificial chromosome (BAC) DNAs from E. coli into the chromosome of Pseudomonas putida in a site-specific manner. The integrase delivery system works in concert with existing vector systems and could thus be a powerful tool for synthetic constructions of new metabolic pathways in a variety of host bacteria.
Collapse
|
21
|
Bi D, Xu Z, Harrison EM, Tai C, Wei Y, He X, Jia S, Deng Z, Rajakumar K, Ou HY. ICEberg: a web-based resource for integrative and conjugative elements found in Bacteria. Nucleic Acids Res 2011; 40:D621-6. [PMID: 22009673 PMCID: PMC3244999 DOI: 10.1093/nar/gkr846] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
ICEberg (http://db-mml.sjtu.edu.cn/ICEberg/) is an integrated database that provides comprehensive information about integrative and conjugative elements (ICEs) found in bacteria. ICEs are conjugative self-transmissible elements that can integrate into and excise from a host chromosome. An ICE contains three typical modules, integration and excision, conjugation, and regulation modules, that collectively promote vertical inheritance and periodic lateral gene flow. Many ICEs carry likely virulence determinants, antibiotic-resistant factors and/or genes coding for other beneficial traits. ICEberg offers a unique, highly organized, readily explorable archive of both predicted and experimentally supported ICE-relevant data. It currently contains details of 428 ICEs found in representatives of 124 bacterial species, and a collection of >400 directly related references. A broad range of similarity search, sequence alignment, genome context browser, phylogenetic and other functional analysis tools are readily accessible via ICEberg. We propose that ICEberg will facilitate efficient, multi-disciplinary and innovative exploration of bacterial ICEs and be of particular interest to researchers in the broad fields of prokaryotic evolution, pathogenesis, biotechnology and metabolism. The ICEberg database will be maintained, updated and improved regularly to ensure its ongoing maximum utility to the research community.
Collapse
Affiliation(s)
- Dexi Bi
- State Key Laboratory of Microbial Metabolism and School of Life Sciences & Biotechnology, Shanghai Jiaotong University, Shanghai 200030, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Toleman MA, Walsh TR. Combinatorial events of insertion sequences and ICE in Gram-negative bacteria. FEMS Microbiol Rev 2011; 35:912-35. [DOI: 10.1111/j.1574-6976.2011.00294.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
23
|
The repertoire of ICE in prokaryotes underscores the unity, diversity, and ubiquity of conjugation. PLoS Genet 2011; 7:e1002222. [PMID: 21876676 PMCID: PMC3158045 DOI: 10.1371/journal.pgen.1002222] [Citation(s) in RCA: 258] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 06/02/2011] [Indexed: 11/19/2022] Open
Abstract
Horizontal gene transfer shapes the genomes of prokaryotes by allowing rapid acquisition of novel adaptive functions. Conjugation allows the broadest range and the highest gene transfer input per transfer event. While conjugative plasmids have been studied for decades, the number and diversity of integrative conjugative elements (ICE) in prokaryotes remained unknown. We defined a large set of protein profiles of the conjugation machinery to scan over 1,000 genomes of prokaryotes. We found 682 putative conjugative systems among all major phylogenetic clades and showed that ICEs are the most abundant conjugative elements in prokaryotes. Nearly half of the genomes contain a type IV secretion system (T4SS), with larger genomes encoding more conjugative systems. Surprisingly, almost half of the chromosomal T4SS lack co-localized relaxases and, consequently, might be devoted to protein transport instead of conjugation. This class of elements is preponderant among small genomes, is less commonly associated with integrases, and is rarer in plasmids. ICEs and conjugative plasmids in proteobacteria have different preferences for each type of T4SS, but all types exist in both chromosomes and plasmids. Mobilizable elements outnumber self-conjugative elements in both ICEs and plasmids, which suggests an extensive use of T4SS in trans. Our evolutionary analysis indicates that switch of plasmids to and from ICEs were frequent and that extant elements began to differentiate only relatively recently. According to the present results, ICEs are the most abundant conjugative elements in practically all prokaryotic clades and might be far more frequently domesticated into non-conjugative protein transport systems than previously thought. While conjugative plasmids and ICEs have different means of genomic stabilization, their mechanisms of mobility by conjugation show strikingly conserved patterns, arguing for a unitary view of conjugation in shaping the genomes of prokaryotes by horizontal gene transfer. Some mobile genetic elements spread genetic information horizontally between prokaryotes by conjugation, a mechanism by which DNA is transferred directly from one cell to the other. Among the processes allowing genetic transfer between cells, conjugation is the one allowing the simultaneous transfer of larger amounts of DNA and between the least related cells. As such, conjugative systems are key players in horizontal transfer, including the transfer of antibiotic resistance to and between many human pathogens. Conjugative systems are encoded both in plasmids and in chromosomes. The latter are called Integrative Conjugative Elements (ICE); and their number, identity, and mechanism of conjugation were poorly known. We have developed an approach to identify and characterize these elements and found more ICEs than conjugative plasmids in genomes. While both ICEs and plasmids use similar conjugative systems, there are remarkable preferences for some systems in some elements. Our evolutionary analysis shows that plasmid conjugative systems have often given rise to ICEs and vice versa. Therefore, ICEs and conjugative plasmids should be regarded as one and the same, the differences in their means of existence in cells probably the result of different requirements for stabilization and/or transmissibility of the genetic information they contain.
Collapse
|
24
|
Abstract
Pseudomonas aeruginosa strains exhibit significant variability in pathogenicity and ecological flexibility. Such interstrain differences reflect the dynamic nature of the P. aeruginosa genome, which is composed of a relatively invariable "core genome" and a highly variable "accessory genome." Here we review the major classes of genetic elements comprising the P. aeruginosa accessory genome and highlight emerging themes in the acquisition and functional importance of these elements. Although the precise phenotypes endowed by the majority of the P. aeruginosa accessory genome have yet to be determined, rapid progress is being made, and a clearer understanding of the role of the P. aeruginosa accessory genome in ecology and infection is emerging.
Collapse
|
25
|
Miyazaki R, van der Meer JR. A dual functional origin of transfer in the ICEclc genomic island of Pseudomonas knackmussii B13. Mol Microbiol 2010; 79:743-58. [DOI: 10.1111/j.1365-2958.2010.07484.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
26
|
ICEEc2, a new integrative and conjugative element belonging to the pKLC102/PAGI-2 family, identified in Escherichia coli strain BEN374. J Bacteriol 2010; 192:5026-36. [PMID: 20675467 DOI: 10.1128/jb.00609-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The diversity of the Escherichia coli species is in part due to the large number of mobile genetic elements that are exchanged between strains. We report here the identification of a new integrative and conjugative element (ICE) of the pKLC102/PAGI-2 family located downstream of the tRNA gene pheU in the E. coli strain BEN374. Indeed, this new region, which we called ICEEc2, can be transferred by conjugation from strain BEN374 to the E. coli strain C600. We were also able to transfer this region into a Salmonella enterica serovar Typhimurium strain and into a Yersinia pseudotuberculosis strain. This transfer was then followed by the integration of ICEEc2 into the host chromosome downstream of a phe tRNA gene. Our data indicated that this transfer involved a set of three genes encoding DNA mobility enzymes and a type IV pilus encoded by genes present on ICEEc2. Given the wide distribution of members of this family, these mobile genetic elements are likely to play an important role in the diversification of bacteria.
Collapse
|
27
|
Wozniak RAF, Waldor MK. Integrative and conjugative elements: mosaic mobile genetic elements enabling dynamic lateral gene flow. Nat Rev Microbiol 2010; 8:552-63. [PMID: 20601965 DOI: 10.1038/nrmicro2382] [Citation(s) in RCA: 525] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Integrative and conjugative elements (ICEs) are a diverse group of mobile genetic elements found in both Gram-positive and Gram-negative bacteria. These elements primarily reside in a host chromosome but retain the ability to excise and to transfer by conjugation. Although ICEs use a range of mechanisms to promote their core functions of integration, excision, transfer and regulation, there are common features that unify the group. This Review compares and contrasts the core functions for some of the well-studied ICEs and discusses them in the broader context of mobile-element and genome evolution.
Collapse
|
28
|
Gaillard M, Pradervand N, Minoia M, Sentchilo V, Johnson DR, van der Meer JR. Transcriptome analysis of the mobile genome ICEclc in Pseudomonas knackmussii B13. BMC Microbiol 2010; 10:153. [PMID: 20504315 PMCID: PMC2892462 DOI: 10.1186/1471-2180-10-153] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 05/26/2010] [Indexed: 11/28/2022] Open
Abstract
Background Integrative and conjugative elements (ICE) form a diverse group of DNA elements that are integrated in the chromosome of the bacterial host, but can occasionally excise and horizontally transfer to a new host cell. ICE come in different families, typically with a conserved core for functions controlling the element's behavior and a variable region providing auxiliary functions to the host. The ICEclc element of Pseudomonas knackmussii strain B13 is representative for a large family of chromosomal islands detected by genome sequencing approaches. It provides the host with the capacity to degrade chloroaromatics and 2-aminophenol. Results Here we study the transcriptional organization of the ICEclc core region. By northern hybridizations, reverse-transcriptase polymerase chain reaction (RT-PCR) and Rapid Amplification of cDNA Ends (5'-RACE) fifteen transcripts were mapped in the core region. The occurrence and location of those transcripts were further confirmed by hybridizing labeled cDNA to a semi-tiling micro-array probing both strands of the ICEclc core region. Dot blot and semi-tiling array hybridizations demonstrated most of the core transcripts to be upregulated during stationary phase on 3-chlorobenzoate, but not on succinate or glucose. Conclusions The transcription analysis of the ICEclc core region provides detailed insights in the mode of regulatory organization and will help to further understand the complex mode of behavior of this class of mobile elements. We conclude that ICEclc core transcription is concerted at a global level, more reminiscent of a phage program than of plasmid conjugation.
Collapse
Affiliation(s)
- Muriel Gaillard
- Department of Fundamental Microbiology, University of Lausanne, Switzerland
| | | | | | | | | | | |
Collapse
|
29
|
Sentchilo V, Czechowska K, Pradervand N, Minoia M, Miyazaki R, van der Meer JR. Intracellular excision and reintegration dynamics of the ICEclcgenomic island ofPseudomonas knackmussiisp. strain B13. Mol Microbiol 2009; 72:1293-306. [DOI: 10.1111/j.1365-2958.2009.06726.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
30
|
Stochasticity and bistability in horizontal transfer control of a genomic island in Pseudomonas. Proc Natl Acad Sci U S A 2008; 105:20792-7. [PMID: 19098098 DOI: 10.1073/pnas.0806164106] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Genomic islands (GEI) comprise a recently recognized large family of potentially mobile DNA elements and play an important role in the rapid differentiation and adaptation of bacteria. Most importantly, GEIs have been implicated in the acquisition of virulence factors, antibiotic resistances or toxic compound metabolism. Despite detailed information on coding capacities of GEIs, little is known about the regulatory decisions in individual cells controlling GEI transfer. Here, we show how self-transfer of ICEclc, a GEI in Pseudomonas knackmussii B13 is controlled by a series of stochastic processes, the result of which is that only a few percent of cells in a population will excise ICEclc and launch transfer. Stochastic processes have been implicated before in producing bistable phenotypic transitions, such as sporulation and competence development, but never before in horizontal gene transfer (HGT). Bistability is instigated during stationary phase at the level of expression of an activator protein InrR that lays encoded on ICEclc, and then faithfully propagated to a bistable expression of the IntB13 integrase, the enzyme responsible for excision and integration of the ICEclc. Our results demonstrate how GEI of a very widespread family are likely to control their transfer rates. Furthermore, they help to explain why HGT is typically confined to few members within a population of cells. The finding that, despite apparent stochasticity, HGT rates can be modulated by external environmental conditions provides an explanation as to why selective conditions can promote DNA exchange.
Collapse
|
31
|
Juhas M, van der Meer JR, Gaillard M, Harding RM, Hood DW, Crook DW. Genomic islands: tools of bacterial horizontal gene transfer and evolution. FEMS Microbiol Rev 2008; 33:376-93. [PMID: 19178566 PMCID: PMC2704930 DOI: 10.1111/j.1574-6976.2008.00136.x] [Citation(s) in RCA: 578] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bacterial genomes evolve through mutations, rearrangements or horizontal gene transfer. Besides the core genes encoding essential metabolic functions, bacterial genomes also harbour a number of accessory genes acquired by horizontal gene transfer that might be beneficial under certain environmental conditions. The horizontal gene transfer contributes to the diversification and adaptation of microorganisms, thus having an impact on the genome plasticity. A significant part of the horizontal gene transfer is or has been facilitated by genomic islands (GEIs). GEIs are discrete DNA segments, some of which are mobile and others which are not, or are no longer mobile, which differ among closely related strains. A number of GEIs are capable of integration into the chromosome of the host, excision, and transfer to a new host by transformation, conjugation or transduction. GEIs play a crucial role in the evolution of a broad spectrum of bacteria as they are involved in the dissemination of variable genes, including antibiotic resistance and virulence genes leading to generation of hospital ‘superbugs’, as well as catabolic genes leading to formation of new metabolic pathways. Depending on the composition of gene modules, the same type of GEIs can promote survival of pathogenic as well as environmental bacteria.
Collapse
Affiliation(s)
- Mario Juhas
- Clinical Microbiology and Infectious Diseases, Nuffield Department of Clinical Laboratory Sciences, University of Oxford, Oxford, UK.
| | | | | | | | | | | |
Collapse
|
32
|
Gross R, Guzman CA, Sebaihia M, dos Santos VAPM, Pieper DH, Koebnik R, Lechner M, Bartels D, Buhrmester J, Choudhuri JV, Ebensen T, Gaigalat L, Herrmann S, Khachane AN, Larisch C, Link S, Linke B, Meyer F, Mormann S, Nakunst D, Rückert C, Schneiker-Bekel S, Schulze K, Vorhölter FJ, Yevsa T, Engle JT, Goldman WE, Pühler A, Göbel UB, Goesmann A, Blöcker H, Kaiser O, Martinez-Arias R. The missing link: Bordetella petrii is endowed with both the metabolic versatility of environmental bacteria and virulence traits of pathogenic Bordetellae. BMC Genomics 2008; 9:449. [PMID: 18826580 PMCID: PMC2572626 DOI: 10.1186/1471-2164-9-449] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2008] [Accepted: 09/30/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bordetella petrii is the only environmental species hitherto found among the otherwise host-restricted and pathogenic members of the genus Bordetella. Phylogenetically, it connects the pathogenic Bordetellae and environmental bacteria of the genera Achromobacter and Alcaligenes, which are opportunistic pathogens. B. petrii strains have been isolated from very different environmental niches, including river sediment, polluted soil, marine sponges and a grass root. Recently, clinical isolates associated with bone degenerative disease or cystic fibrosis have also been described. RESULTS In this manuscript we present the results of the analysis of the completely annotated genome sequence of the B. petrii strain DSMZ12804. B. petrii has a mosaic genome of 5,287,950 bp harboring numerous mobile genetic elements, including seven large genomic islands. Four of them are highly related to the clc element of Pseudomonas knackmussii B13, which encodes genes involved in the degradation of aromatics. Though being an environmental isolate, the sequenced B. petrii strain also encodes proteins related to virulence factors of the pathogenic Bordetellae, including the filamentous hemagglutinin, which is a major colonization factor of B. pertussis, and the master virulence regulator BvgAS. However, it lacks all known toxins of the pathogenic Bordetellae. CONCLUSION The genomic analysis suggests that B. petrii represents an evolutionary link between free-living environmental bacteria and the host-restricted obligate pathogenic Bordetellae. Its remarkable metabolic versatility may enable B. petrii to thrive in very different ecological niches.
Collapse
Affiliation(s)
- Roy Gross
- Chair of Microbiology, Biocenter, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Host and invader impact of transfer of the clc genomic island into Pseudomonas aeruginosa PAO1. Proc Natl Acad Sci U S A 2008; 105:7058-63. [PMID: 18448680 DOI: 10.1073/pnas.0801269105] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genomic islands, large potentially mobile regions of bacterial chromosomes, are a major contributor to bacteria evolution. Here, we investigated the fitness cost and phenotypic differences between the bacterium Pseudomonas aeruginosa PAO1 and a derivative carrying one integrated copy of the clc element, a 103-kb genomic island [and integrative and conjugative element (ICE)] originating in Pseudomonas sp. strain B13 and a close relative of genomic islands found in clinical and environmental isolates of P. aeruginosa. By using a combination of whole genome transcriptome profiling, phenotypic arrays, competition experiments, and biofilm formation studies, only few differences became apparent, such as reduced biofilm growth and fourfold stationary phase repression of genes involved in acetoin metabolism in PAO1 containing the clc element. In contrast, PAO1 carrying the clc element acquired the capacity to grow on 3-chlorobenzoate and 2-aminophenol as sole carbon and energy substrates. No fitness loss >1% was detectable in competition experiments between PAO1 and PAO1 carrying the clc element. The genes from the clc element were not silent in PAO1, and excision was observed, although transfer of clc from PAO1 to other recipient bacteria was reduced by two orders of magnitude. Our results indicate that newly acquired mobile DNA not necessarily invoke an important fitness cost on their host. Absence of immediate detriment to the host may have contributed to the wide distribution of genomic islands like clc in bacterial genomes.
Collapse
|
34
|
Serra-Moreno R, Jofre J, Muniesa M. Insertion site occupancy by stx2 bacteriophages depends on the locus availability of the host strain chromosome. J Bacteriol 2007; 189:6645-54. [PMID: 17644594 PMCID: PMC2045183 DOI: 10.1128/jb.00466-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is an emergent pathogen characterized by the expression of Shiga toxins, which are encoded in the genomes of lambdoid phages. These phages are infectious for other members of the Enterobacteriaceae and establish lysogeny when they integrate into the host chromosome. Five insertion sites, used mainly by these prophages, have been described to date. In the present study, the insertion of stx(2) prophages in these sites was analyzed in 168 STEC strains isolated from cattle. Additionally, insertion sites were determined for stx(2) phages which (i) converted diverse laboratory host strains, (ii) coexisted with another stx(2) prophage, and (iii) infected a recombinant host strain lacking the most commonly used insertion site. Results show that depending on the host strain, phages preferentially use one insertion site. For the most part, yehV is occupied in STEC strains while wrbA is preferentially selected by the same stx phages in E. coli laboratory strains. If this primary insertion site is unavailable, then a secondary insertion site is selected. It can be concluded that insertion site occupancy by stx phages depends on the host strain and on the availability of the preferred locus in the host strain.
Collapse
|
35
|
Le Bourgeois P, Bugarel M, Campo N, Daveran-Mingot ML, Labonté J, Lanfranchi D, Lautier T, Pagès C, Ritzenthaler P. The unconventional Xer recombination machinery of Streptococci/Lactococci. PLoS Genet 2007; 3:e117. [PMID: 17630835 PMCID: PMC1914069 DOI: 10.1371/journal.pgen.0030117] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 06/04/2007] [Indexed: 11/19/2022] Open
Abstract
Homologous recombination between circular sister chromosomes during DNA replication in bacteria can generate chromosome dimers that must be resolved into monomers prior to cell division. In Escherichia coli, dimer resolution is achieved by site-specific recombination, Xer recombination, involving two paralogous tyrosine recombinases, XerC and XerD, and a 28-bp recombination site (dif) located at the junction of the two replication arms. Xer recombination is tightly controlled by the septal protein FtsK. XerCD recombinases and FtsK are found on most sequenced eubacterial genomes, suggesting that the Xer recombination system as described in E. coli is highly conserved among prokaryotes. We show here that Streptococci and Lactococci carry an alternative Xer recombination machinery, organized in a single recombination module. This corresponds to an atypical 31-bp recombination site (dif(SL)) associated with a dedicated tyrosine recombinase (XerS). In contrast to the E. coli Xer system, only a single recombinase is required to recombine dif(SL), suggesting a different mechanism in the recombination process. Despite this important difference, XerS can only perform efficient recombination when dif(SL) sites are located on chromosome dimers. Moreover, the XerS/dif(SL) recombination requires the streptococcal protein FtsK(SL), probably without the need for direct protein-protein interaction, which we demonstrated to be located at the division septum of Lactococcus lactis. Acquisition of the XerS recombination module can be considered as a landmark of the separation of Streptococci/Lactococci from other firmicutes and support the view that Xer recombination is a conserved cellular function in bacteria, but that can be achieved by functional analogs.
Collapse
Affiliation(s)
- Pascal Le Bourgeois
- Laboratoire de Microbiologie et Génétique Microbienne, CNRS, Université Paul Sabatier, Toulouse, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Klockgether J, Würdemann D, Reva O, Wiehlmann L, Tümmler B. Diversity of the abundant pKLC102/PAGI-2 family of genomic islands in Pseudomonas aeruginosa. J Bacteriol 2007; 189:2443-59. [PMID: 17194795 PMCID: PMC1899365 DOI: 10.1128/jb.01688-06] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Accepted: 01/08/2007] [Indexed: 12/27/2022] Open
Abstract
The known genomic islands of Pseudomonas aeruginosa clone C strains are integrated into tRNA(Lys) (pKLC102) or tRNA(Gly) (PAGI-2 and PAGI-3) genes and differ from their core genomes by distinctive tetranucleotide usage patterns. pKLC102 and the related island PAPI-1 from P. aeruginosa PA14 were spontaneously mobilized from their host chromosomes at frequencies of 10% and 0.3%, making pKLC102 the most mobile genomic island known with a copy number of 30 episomal circular pKLC102 molecules per cell. The incidence of islands of the pKLC102/PAGI-2 type was investigated in 71 unrelated P. aeruginosa strains from diverse habitats and geographic origins. pKLC102- and PAGI-2-like islands were identified in 50 and 31 strains, respectively, and 15 and 10 subtypes were differentiated by hybridization on pKLC102 and PAGI-2 macroarrays. The diversity of PAGI-2-type islands was mainly caused by one large block of strain-specific genes, whereas the diversity of pKLC102-type islands was primarily generated by subtype-specific combination of gene cassettes. Chromosomal loss of PAGI-2 could be documented in sequential P. aeruginosa isolates from individuals with cystic fibrosis. PAGI-2 was present in most tested Cupriavidus metallidurans and Cupriavidus campinensis isolates from polluted environments, demonstrating the spread of PAGI-2 across habitats and species barriers. The pKLC102/PAGI-2 family is prevalent in numerous beta- and gammaproteobacteria and is characterized by high asymmetry of the cDNA strands. This evolutionarily ancient family of genomic islands retained its oligonucleotide signature during horizontal spread within and among taxa.
Collapse
Affiliation(s)
- Jens Klockgether
- Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | | | | | | | | |
Collapse
|
37
|
Ramsay JP, Sullivan JT, Stuart GS, Lamont IL, Ronson CW. Excision and transfer of the Mesorhizobium loti R7A symbiosis island requires an integrase IntS, a novel recombination directionality factor RdfS, and a putative relaxase RlxS. Mol Microbiol 2007; 62:723-34. [PMID: 17076666 DOI: 10.1111/j.1365-2958.2006.05396.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Mesorhizobium loti strain R7A symbiosis island is an Integrative Conjugative Element (ICE), herein termed ICEMlSymR7A, which integrates into a phetRNA gene. Integration reconstructs the phetRNA gene at one junction with the core chromosome, and a direct repeat of the 3-prime 17 bp of the gene is formed at the other junction. We show that the ICEMlSymR7AintS gene, which encodes an integrase of the phage P4 family, is required for integration and excision of the island. Excision also depended on a novel recombination directionality factor encoded by msi109 (rdfS). Constitutive expression of rdfS resulted in curing of ICEMlSymR7A. The rdfS gene is part of an operon with genes required for conjugative transfer, allowing co-ordinate regulation of ICEMlSymR7A excision and transfer. The excised form of ICEMlSymR7A was detectable during exponential growth but occurred at higher frequency during stationary phase. ICEMlSymR7A encodes homologues of the traR and traI genes of Agrobacterium tumefaciens that regulate Ti plasmid transfer via quorum sensing. The presence of a plasmid with cloned island traR traI2 genes resulted in excision of ICEMlSymR7A in all cells regardless of culture density, indicating that excision may be similarly regulated. Maintenance of ICEMlSymR7A in these cells depended on msi106 (rlxS) that encodes a putative relaxase. Transfer of the island to non-symbiotic mesorhizobia required intS, rlxS and rdfS. The rdfS and rlxS genes are conserved across a diverse range of alpha-, beta- and gamma-proteobacteria and identify a large family of genomic islands with a common transfer mechanism.
Collapse
Affiliation(s)
- Joshua P Ramsay
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | | | | | | | | |
Collapse
|
38
|
Qiu X, Gurkar AU, Lory S. Interstrain transfer of the large pathogenicity island (PAPI-1) of Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2006; 103:19830-5. [PMID: 17179047 PMCID: PMC1750864 DOI: 10.1073/pnas.0606810104] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The large Pseudomonas aeruginosa pathogenicity island PAPI-1 of strain PA14 is a cluster of 108 genes that encode a number of virulence features. We demonstrate that, in a subpopulation of cells, PAPI-1 can exist in an extrachromosomal circular form after precise excision from its integration site within the 3' terminus of the tRNA(Lys) gene. Circular PAPI-1 can reintegrate into either of the two tRNA(Lys) genes, including the one that was used for integration of small pathogenicity island PAPI-2 in strain PA14. The excision requires PAPI-1-encoded integrase, a member of the tyrosine recombinase family. PAPI-1 Soj contains the conserved domains of proteins that are related to chromosome and plasmid partition. soj plays a role in maintaining PAPI-1 and mutations in soj result in the loss of PAPI-1 from P. aeruginosa. We further demonstrate that, during coculture, the PAPI-1-containing strains are able to transfer it into P. aeruginosa recipient strains that do not harbor this island naturally. After transfer, PAPI-1 integrates into either of the two tRNA(Lys) genes. PAPI-1 encompasses many features of mobile elements, including mobilization and maintenance modules. Together with the virulence determinants, PAPI-1 plays an important role in the evolution of P. aeruginosa, by expanding its natural habitat from soil and water to animal and human infections.
Collapse
Affiliation(s)
- Xiaoyun Qiu
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | - Aditi U. Gurkar
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | - Stephen Lory
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
- *To whom correspondence should be addressed. E-mail:
| |
Collapse
|
39
|
Pitman AR, Jackson RW, Mansfield JW, Kaitell V, Thwaites R, Arnold DL. Exposure to host resistance mechanisms drives evolution of bacterial virulence in plants. Curr Biol 2006; 15:2230-5. [PMID: 16360685 DOI: 10.1016/j.cub.2005.10.074] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 10/21/2005] [Accepted: 10/21/2005] [Indexed: 12/26/2022]
Abstract
Bacterial pathogenicity to plants and animals has evolved through an arms race of attack and defense. Key players are bacterial effector proteins, which are delivered through the type III secretion system and suppress basal defenses . In plants, varietal resistance to disease is based on recognition of effectors by the products of resistance (R) genes . When recognized, the effector or in this scenario, avirulence (Avr) protein triggers the hypersensitive resistance reaction (HR), which generates antimicrobial conditions . Unfortunately, such gene-for-gene-based resistance commonly fails because of the emergence of virulent strains of the pathogen that no longer trigger the HR . We have followed the emergence of a new virulent pathotype of the halo-blight pathogen Pseudomonas syringae pv. phaseolicola within leaves of a resistant variety of bean. Exposure to the HR led to the selection of strains lacking the avirulence (effector) gene avrPphB (or hopAR1), which triggers defense in varieties with the matching R3 resistance gene. Loss of avrPphB was through deletion of a 106 kb genomic island (PPHGI-1) that shares features with integrative and conjugative elements (ICElands) and also pathogenicity islands (PAIs) in diverse bacteria . We provide a molecular explanation of how exposure to resistance mechanisms in plants drives the evolution of new virulent forms of pathogens.
Collapse
Affiliation(s)
- Andrew R Pitman
- Centre for Research in Plant Science, University of the West of England, Bristol, BS16 1QY, United Kingdom
| | | | | | | | | | | |
Collapse
|
40
|
Muniesa M, Schembri MA, Hauf N, Chakraborty T. Active genetic elements present in the locus of enterocyte effacement in Escherichia coli O26 and their role in mobility. Infect Immun 2006; 74:4190-9. [PMID: 16790794 PMCID: PMC1489727 DOI: 10.1128/iai.00926-05] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The locus of enterocyte effacement (LEE) is a large multigene chromosomal segment encoding gene products responsible for the generation of attaching and effacing lesions in many diarrheagenic Escherichia coli strains. A recently sequenced LEE harboring a pathogenicity island (PAI) from a Shiga toxin E. coli serotype O26 strain revealed a LEE PAI (designated LEE O26) almost identical to that obtained from a rabbit-specific enteropathogenic O15:H- strain. LEE O26 comprises 59,540 bp and is inserted at 94 min within the mature pheU tRNA locus. The LEE O26 PAI is flanked by two direct repeats of 137 and 136 bp (DR1 and DR2), as well as a gene encoding an integrase belonging to the P4 integrase family. We examined LEE O26 for horizontal gene transfer. By generating mini-LEE plasmids harboring only DR1 or DR2 with or without the integrase-like gene, we devised a simple assay to examine recombination processes between these sequences. Recombination was shown to be integrase dependent in a DeltarecA E. coli K-12 strain background. Recombinant plasmids harboring a single direct repeat cloned either with or without the LEE O26 integrase gene were found to insert within the chromosomal pheU locus of E. coli K-12 strains with equal efficiency, suggesting that an endogenous P4-like integrase can substitute for this activity. An integrase with strong homology to the LEE O26 integrase was detected on the K-12 chromosome associated with the leuX tRNA locus at 97 min. Strains deleted for this integrase demonstrated a reduction in the insertion frequency of plasmids harboring only the DR into the pheU locus. These results provide strong evidence that LEE-harboring elements are indeed mobile and suggest that closely related integrases present on the chromosome of E. coli strains contribute to the dynamics of PAI mobility.
Collapse
Affiliation(s)
- Maite Muniesa
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | | | | | | |
Collapse
|
41
|
Gaillard M, Vallaeys T, Vorhölter FJ, Minoia M, Werlen C, Sentchilo V, Pühler A, van der Meer JR. The clc element of Pseudomonas sp. strain B13, a genomic island with various catabolic properties. J Bacteriol 2006; 188:1999-2013. [PMID: 16484212 PMCID: PMC1426575 DOI: 10.1128/jb.188.5.1999-2013.2006] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Pseudomonas sp. strain B13 is a bacterium known to degrade chloroaromatic compounds. The properties to use 3- and 4-chlorocatechol are determined by a self-transferable DNA element, the clc element, which normally resides at two locations in the cell's chromosome. Here we report the complete nucleotide sequence of the clc element, demonstrating the unique catabolic properties while showing its relatedness to genomic islands and integrative and conjugative elements rather than to other known catabolic plasmids. As far as catabolic functions, the clc element harbored, in addition to the genes for chlorocatechol degradation, a complete functional operon for 2-aminophenol degradation and genes for a putative aromatic compound transport protein and for a multicomponent aromatic ring dioxygenase similar to anthranilate hydroxylase. The genes for catabolic functions were inducible under various conditions, suggesting a network of catabolic pathway induction. For about half of the open reading frames (ORFs) on the clc element, no clear functional prediction could be given, although some indications were found for functions that were similar to plasmid conjugation. The region in which these ORFs were situated displayed a high overall conservation of nucleotide sequence and gene order to genomic regions in other recently completed bacterial genomes or to other genomic islands. Most notably, except for two discrete regions, the clc element was almost 100% identical over the whole length to a chromosomal region in Burkholderia xenovorans LB400. This indicates the dynamic evolution of this type of element and the continued transition between elements with a more pathogenic character and those with catabolic properties.
Collapse
Affiliation(s)
- Muriel Gaillard
- Department of Fundamental Microbiology, Bātiment Biophore, University of Lausanne, CH-1015 Lausanne, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Liu S, Ogawa N, Senda T, Hasebe A, Miyashita K. Amino acids in positions 48, 52, and 73 differentiate the substrate specificities of the highly homologous chlorocatechol 1,2-dioxygenases CbnA and TcbC. J Bacteriol 2005; 187:5427-36. [PMID: 16030237 PMCID: PMC1196051 DOI: 10.1128/jb.187.15.5427-5436.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chlorocatechol 1,2-dioxygenase (CCD) is the first-step enzyme of the chlorocatechol ortho-cleavage pathway, which plays a central role in the degradation of various chloroaromatic compounds. Two CCDs, CbnA from the 3-chlorobenzoate-degrader Ralstonia eutropha NH9 and TcbC from the 1,2,4-trichlorobenzene-degrader Pseudomonas sp. strain P51, are highly homologous, having only 12 different amino acid residues out of identical lengths of 251 amino acids. But CbnA and TcbC are different in substrate specificities against dichlorocatechols, favoring 3,5-dichlorocatechol (3,5-DC) and 3,4-dichlorocatechol (3,4-DC), respectively. A study of chimeric mutants constructed from the two CCDs indicated that the N-terminal parts of the enzymes were responsible for the difference in the substrate specificities. Site-directed mutagenesis studies further identified the amino acid in position 48 (Leu in CbnA and Val in TcbC) as critical in differentiating the substrate specificities of the enzymes, which agreed well with molecular modeling of the two enzymes. Mutagenesis studies also demonstrated that Ile-73 of CbnA and Ala-52 of TcbC were important for their high levels of activity towards 3,5-DC and 3,4-DC, respectively. The importance of Ile-73 for 3,5-DC specificity determination was also shown with other CCDs such as TfdC from Burkholderia sp. NK8 and TfdC from Alcaligenes sp. CSV90 (identical to TfdC from R. eutropha JMP134), which convert 3,5-DC preferentially. Together with amino acid sequence comparisons indicating high conservation of Leu-48 and Ile-73 among CCDs, these results suggested that TcbC of strain P51 had diverged from other CCDs to be adapted to conversion of 3,4-DC.
Collapse
Affiliation(s)
- Shenghao Liu
- National Institute for Agro-Environmental Sciences, 3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan
| | | | | | | | | |
Collapse
|
43
|
Lang GH, Ogawa N, Tanaka Y, Fujii T, Fulthorpe RR, Fukuda M, Miyashita K. Two kinds of chlorocatechol 1,2-dioxygenase from 2,4-dichlorophenoxyacetate-degrading Sphingomonas sp. strain TFD44. Biochem Biophys Res Commun 2005; 332:941-8. [PMID: 15916749 DOI: 10.1016/j.bbrc.2005.05.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Accepted: 05/10/2005] [Indexed: 11/23/2022]
Abstract
Two kinds of chlorocatechol 1,2-dioxygenase (CCD), TfdC and TfdC2 were detected in Sphingomonas sp. strain TFD44. These two CCDs could be simultaneously synthesized in TFD44 during its growth with 2,4-D as the sole carbon and energy sources. The apparent subunit molecular masses of TfdC and TfdC2 estimated by SDS-PAGE analysis were 33.8 and 33.1 kDa, respectively. The genes encoding the two CCDs were cloned and expressed in Escherichia coli. The two purified CCDs showed broad substrate specificities but had different specificity patterns. TfdC showed the highest specificity constant for 3-chlorocatechol and TfdC2 showed the highest specificity constant for 3,5-dichlorocatechol. The substrate specificity difference seemed to correlate with the alternation of amino acid supposed to be involved in the interaction with substrates. Whereas phylogenetic analysis indicated that the CCDs of Sphingomonas constitute a distinctive group among Gram-negative bacteria, TfdC and TfdC2 of TFD44 have divergently evolved in terms of their substrate specificity.
Collapse
Affiliation(s)
- Gang-hua Lang
- National Institute for Agro-Environmental Sciences, 3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan
| | | | | | | | | | | | | |
Collapse
|
44
|
Tropel D, van der Meer JR. Characterization of HbpR binding by site-directed mutagenesis of its DNA-binding site and by deletion of the effector domain. FEBS J 2005; 272:1756-66. [PMID: 15794762 DOI: 10.1111/j.1742-4658.2005.04607.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the presence of 2-hydroxybiphenyl, the enhancer binding protein, HbpR, activates the sigma54-dependent P(hbpC) promoter and controls the initial steps of 2-hydroxybiphenyl degradation in Pseudomonas azelaica. In the activation process, an oligomeric HbpR complex of unknown subunit composition binds to an operator region containing two imperfect palindromic sequences. Here, the HbpR-DNA binding interactions were investigated by site-directed mutagenesis of the operator region and by DNA-binding assays using purified HbpR. Mutations that disrupted the twofold symmetry in the palindromes did not affect the binding affinity of HbpR, but various mutations along a 60 bp region, and also outside the direct palindromic sequences, decreased the binding affinity. Footprints of HbpR on mutant operator fragments showed that a partial loss of binding contacts occurs, suggesting that the binding of one HbpR 'protomer' in the oligomeric complex is impaired whilst leaving the other contacts intact. An HbpR variant, devoid of its N-terminal sensing A-domain, was unable to activate transcription from the hbpC promoter while maintaining protection of the operator DNA in footprints. Wild-type HbpR was unable to activate transcription from the hbpC promoter when delta A-HbpR was expressed in the same cell, suggesting the formation of (repressing) hetero-oligomers. This model implies that HbpR can self-associate on its operator DNA without effector recognition or ATP binding. Furthermore, our findings suggest that the N-terminal sensing domain of HbpR is needed to activate the central ATPase domain rather than to repress a constitutively active C domain, as is the case for the related regulatory protein XylR.
Collapse
Affiliation(s)
- David Tropel
- Process of Environmental Microbiology and Molecular Ecotoxicology, Swiss Federal Institute for Environmental Science and Technology (EAWAG), Dübendorf, Switzerland
| | | |
Collapse
|
45
|
Tropel D, Bähler A, Globig K, van der Meer JR. Design of new promoters and of a dual-bioreporter based on cross-activation by the two regulatory proteins XylR and HbpR. Environ Microbiol 2005; 6:1186-96. [PMID: 15479251 DOI: 10.1111/j.1462-2920.2004.00645.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The HbpR protein is the sigma54-dependent transcription activator for 2-hydroxybiphenyl degradation in Pseudomonas azelaica. The ability of HbpR and XylR, which share 35% amino acid sequence identity, to cross-activate the PhbpC and Pu promoters was investigated by determining HbpR- or XylR-mediated luciferase expression and by DNA binding assays. XylR measurably activated the PhbpC promoter in the presence of the effector m-xylene, both in Escherichia coli and Pseudomonas putida. HbpR weakly stimulated the Pu promoter in E. coli but not in P. azelaica. Poor HbpR-dependent activation from Pu was caused by a weak binding to the operator region. To create promoters efficiently activated by both regulators, the HbpR binding sites on PhbpC were gradually changed into the XylR binding sites of Pu by site-directed mutagenesis. Inducible luciferase expression from mutated promoters was tested in E. coli on a two plasmid system, and from mono copy gene fusions in P. azelaica and P. putida. Some mutants were efficiently activated by both HbpR and XylR, showing that promoters can be created which are permissive for both regulators. Others achieved a higher XylR-dependent transcription than from Pu itself. Mutants were also obtained which displayed a tenfold lower uninduced expression level by HbpR than the wild-type PhbpC, while keeping the same maximal induction level. On the basis of these results, a dual-responsive bioreporter strain of P. azelaica was created, containing both XylR and HbpR, and activating luciferase expression from the same single promoter independently with m-xylene and 2-hydroxybiphenyl.
Collapse
Affiliation(s)
- David Tropel
- Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH-8600 Dübendorf, Switzerland
| | | | | | | |
Collapse
|
46
|
Pieper DH. Aerobic degradation of polychlorinated biphenyls. Appl Microbiol Biotechnol 2004; 67:170-91. [PMID: 15614564 DOI: 10.1007/s00253-004-1810-4] [Citation(s) in RCA: 226] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 10/10/2004] [Accepted: 10/19/2004] [Indexed: 10/26/2022]
Abstract
The microbial degradation of polychlorinated biphenyls (PCBs) has been extensively studied in recent years. The genetic organization of biphenyl catabolic genes has been elucidated in various groups of microorganisms, their structures have been analyzed with respect to their evolutionary relationships, and new information on mobile elements has become available. Key enzymes, specifically biphenyl 2,3-dioxygenases, have been intensively characterized, structure/sequence relationships have been determined and enzymes optimized for PCB transformation. However, due to the complex metabolic network responsible for PCB degradation, optimizing degradation by single bacterial species is necessarily limited. As PCBs are usually not mineralized by biphenyl-degrading organisms, and cometabolism can result in the formation of toxic metabolites, the degradation of chlorobenzoates has received special attention. A broad set of bacterial strategies to degrade chlorobenzoates has recently been elucidated, including new pathways for the degradation of chlorocatechols as central intermediates of various chloroaromatic catabolic pathways. To optimize PCB degradation in the environment beyond these metabolic limitations, enhancing degradation in the rhizosphere has been suggested, in addition to the application of surfactants to overcome bioavailability barriers. However, further research is necessary to understand the complex interactions between soil/sediment, pollutant, surfactant and microorganisms in different environments.
Collapse
Affiliation(s)
- Dietmar H Pieper
- Department of Environmental Microbiology, German Research Center for Biotechnology, Mascheroder Weg 1, 38124, Braunschweig, Germany.
| |
Collapse
|
47
|
Mohd-Zain Z, Turner SL, Cerdeño-Tárraga AM, Lilley AK, Inzana TJ, Duncan AJ, Harding RM, Hood DW, Peto TE, Crook DW. Transferable antibiotic resistance elements in Haemophilus influenzae share a common evolutionary origin with a diverse family of syntenic genomic islands. J Bacteriol 2004; 186:8114-22. [PMID: 15547285 PMCID: PMC529066 DOI: 10.1128/jb.186.23.8114-8122.2004] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Transferable antibiotic resistance in Haemophilus influenzae was first detected in the early 1970s. After this, resistance spread rapidly worldwide and was shown to be transferred by a large 40- to 60-kb conjugative element. Bioinformatics analysis of the complete sequence of a typical H. influenzae conjugative resistance element, ICEHin1056, revealed the shared evolutionary origin of this element. ICEHin1056 has homology to 20 contiguous sequences in the National Center for Biotechnology Information database. Systematic comparison of these homologous sequences resulted in identification of a conserved syntenic genomic island consisting of up to 33 core genes in 16 beta- and gamma-Proteobacteria. These diverse genomic islands shared a common evolutionary origin, insert into tRNA genes, and have diverged widely, with G+C contents ranging from 40 to 70% and amino acid homologies as low as 20 to 25% for shared core genes. These core genes are likely to account for the conjugative transfer of the genomic islands and may even encode autonomous replication. Accessory gene clusters were nestled among the core genes and encode the following diverse major attributes: antibiotic, metal, and antiseptic resistance; degradation of chemicals; type IV secretion systems; two-component signaling systems; Vi antigen capsule synthesis; toxin production; and a wide range of metabolic functions. These related genomic islands include the following well-characterized structures: SPI-7, found in Salmonella enterica serovar Typhi; PAP1 or pKLC102, found in Pseudomonas aeruginosa; and the clc element, found in Pseudomonas sp. strain B13. This is the first report of a diverse family of related syntenic genomic islands with a deep evolutionary origin, and our findings challenge the view that genomic islands consist only of independently evolving modules.
Collapse
Affiliation(s)
- Zaini Mohd-Zain
- Infectious Diseases and Clinical Microbiology, John Radcliffe Hospital, University of Oxford, Headington, Oxford, OX3 9DU, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Burrus V, Waldor MK. Shaping bacterial genomes with integrative and conjugative elements. Res Microbiol 2004; 155:376-86. [PMID: 15207870 DOI: 10.1016/j.resmic.2004.01.012] [Citation(s) in RCA: 296] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Accepted: 01/20/2004] [Indexed: 11/30/2022]
Abstract
Integrative and conjugative elements (ICEs) are self-transmissible mobile genetic elements that are increasingly recognized to contribute to lateral gene flow in prokaryotes. ICEs, like most temperate bacteriophages integrate into the genome and like conjugative plasmids disseminate by conjugative transfer to new hosts. Thought of schematically, the structure of ICEs is similar to that of other types of the mobile elements; ICEs have a backbone composed of three modules ensuring maintenance, dissemination and regulation. This backbone can acquire additional functions probably through the action of insertion sequences, transposons and specific recombinases. Previously, ICEs were thought of as only vectors for transfer of antibiotic resistance genes, but it is now evident that ICEs can mediate the transfer of a very diverse set of functions. ICEs allow bacteria to rapidly adapt to new environmental conditions and to colonize new niches. Like phages and conjugative plasmids they also likely mediate the transfer of virulence determinants. ICEs shape the bacterial genome, promoting variability between strains of the same species and distributing genes between unrelated bacterial genera. Finally, we propose that by utilizing conserved integration sites, ICEs may promote the mobilization of genomic islands.
Collapse
Affiliation(s)
- Vincent Burrus
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, and Howard Hughes Medical Institute, 136 Harrison Avenue, Boston, MA 02111, USA.
| | | |
Collapse
|
49
|
McGrath BM, Pembroke J. Detailed analysis of the insertion site of the mobile elements R997, pMERPH, R392, R705 and R391 inE. coliK12. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09673.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
|
50
|
Phoenix P, Keane A, Patel A, Bergeron H, Ghoshal S, Lau PCK. Characterization of a new solvent-responsive gene locus in Pseudomonas putida F1 and its functionalization as a versatile biosensor. Environ Microbiol 2004; 5:1309-27. [PMID: 14641576 DOI: 10.1111/j.1462-2920.2003.00426.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A new gene cluster, designated sepABC and a divergently transcribed sepR, was found downstream of the two-component todST phosphorelay system that regulates toluene degradation (the tod pathway) in Pseudomonas putida F1 (PpF1). The deduced amino acid sequences encoded by sepABC show a high homology to bacterial proteins known to be involved in solvent efflux or multidrug pumps. SepA, SepB and SepC are referred to be periplasmic, inner membrane and outer membrane efflux proteins respectively. Effects on growth of various PpF1 mutants compared to that of the wild type in the presence of toluene indicated a possible protective role of the solvent efflux system in a solvent-stressed environment. Growth tests with the complemented mutants confirmed the involvement of the Sep proteins in conferring solvent tolerance. The sepR gene encodes a 260-residue polypeptide that is a member of the E. coli IclR repressor protein family. The repressor role of SepR was established by conducting tests with a sep-lacZ transcriptional fusion in Escherichia coli and PpF1, expression of SepR as a maltose-binding fusion protein in a DNA binding assay, and mRNA analysis. Southern hybridization experiments and analysis of the P. putida KT2440 genome sequence indicated that sepR is a relatively rare commodity compared to homologues of the sepABC genes. We developed a whole-cell bioluminescent biosensor, PpF1G4, which contains a chromosomally based sep-lux transcriptional fusion. The biosensor showed significant induction of the sepABC genes by a wide variety of aromatic molecules, including benzene, toluene, ethylbenzene, and all three isomers of xylene (BTEX), naphthalene, and complex mixtures of aliphatic and aromatic hydrocarbons. PpF1G4 represents a second-generation biosensor that is not based on a catabolic promoter but is nonetheless inducible by aromatic pollutants and moreover functional under nutrient-rich conditions.
Collapse
MESH Headings
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Base Sequence
- Biosensing Techniques
- DNA, Bacterial/chemistry
- DNA, Bacterial/isolation & purification
- Environmental Pollutants/analysis
- Environmental Pollutants/metabolism
- Gene Deletion
- Gene Expression Regulation, Bacterial
- Genes, Bacterial
- Genes, Reporter
- Genetic Complementation Test
- Hydrocarbons, Aromatic/analysis
- Hydrocarbons, Aromatic/metabolism
- Hydrocarbons, Aromatic/pharmacology
- Lac Operon
- Luminescent Measurements
- Membrane Transport Proteins/genetics
- Membrane Transport Proteins/metabolism
- Molecular Sequence Data
- Promoter Regions, Genetic
- Pseudomonas putida/genetics
- Pseudomonas putida/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Sequence Analysis, DNA
- Sequence Homology
- Solvents/analysis
- Solvents/metabolism
- Solvents/pharmacology
- Toluene/metabolism
- Toluene/pharmacology
- beta-Galactosidase/metabolism
Collapse
Affiliation(s)
- P Phoenix
- Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Ave., Montreal, Quebec, Canada H4P 2R2
| | | | | | | | | | | |
Collapse
|