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Isenberg RY, Holschbach CS, Gao J, Mandel MJ. Functional analysis of cyclic diguanylate-modulating proteins in Vibrio fischeri. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.24.550417. [PMID: 37546929 PMCID: PMC10402110 DOI: 10.1101/2023.07.24.550417] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
As bacterial symbionts transition from a motile free-living state to a sessile biofilm state, they must coordinate behavior changes suitable to each lifestyle. Cyclic diguanylate (c-di-GMP) is an intracellular signaling molecule that can regulate this transition, and it is synthesized by diguanylate cyclase (DGC) enzymes and degraded by phosphodiesterase (PDE) enzymes. Generally, c-di-GMP inhibits motility and promotes biofilm formation. While c-di-GMP and the enzymes that contribute to its metabolism have been well-studied in pathogens, considerably less focus has been placed on c-di-GMP regulation in beneficial symbionts. Vibrio fischeri is the sole beneficial symbiont of the Hawaiian bobtail squid ( Euprymna scolopes ) light organ, and the bacterium requires both motility and biofilm formation to efficiently colonize. C-di-GMP regulates swimming motility and cellulose exopolysaccharide production in V. fischeri . The genome encodes 50 DGCs and PDEs, and while a few of these proteins have been characterized, the majority have not undergone comprehensive characterization. In this study, we use protein overexpression to systematically characterize the functional potential of all 50 V. fischeri proteins. All 28 predicted DGCs and 14 predicted PDEs displayed at least one phenotype consistent with their predicted function, and a majority of each displayed multiple phenotypes. Finally, active site mutant analysis of proteins with the potential for both DGC and PDE activities revealed potential activities for these proteins. This work presents a systems-level functional analysis of a family of signaling proteins in a tractable animal symbiont and will inform future efforts to characterize the roles of individual proteins during lifestyle transitions.
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Affiliation(s)
- Ruth Y. Isenberg
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI USA
- Current address: Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN USA
| | - Chandler S. Holschbach
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
| | - Jing Gao
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL USA
| | - Mark J. Mandel
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI USA
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2
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Zhu W, Liu J, Zhang Y, Zhao D, Li S, Dou H, Wang H, Xia X. The role of rcpA gene in regulating biofilm formation and virulence in Vibrio parahaemolyticus. Int J Food Microbiol 2024; 418:110714. [PMID: 38677238 DOI: 10.1016/j.ijfoodmicro.2024.110714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 04/14/2024] [Accepted: 04/18/2024] [Indexed: 04/29/2024]
Abstract
Vibrio parahaemolyticus (V. parahaemolyticus) is a common seafood-borne pathogen that can colonize the intestine of host and cause gastroenteritis. Biofilm formation by V. parahaemolyticus enhances its persistence in various environments, which poses a series of threats to food safety. This work aims to investigate the function of rcpA gene in biofilm formation and virulence of V. parahaemolyticus. Deletion of rcpA significantly reduced motility, biofilm biomass, and extracellular polymeric substances, and inhibited biofilm formation on a variety of food and food contact surfaces. In mice infection model, mice infected with ∆rcpA strain exhibited a decreased rate of pathogen colonization, a lower level of inflammatory cytokines, and less tissue damage when compared to mice infected with wild type strain. RNA-seq analysis revealed that 374 genes were differentially expressed in the rcpA deletion mutant, which include genes related to quorum sensing, flagellar system, ribosome, type VI secretion system, biotin metabolism and transcriptional regulation. In conclusion, rcpA plays a role in determining biofilm formation and virulence of V. parahaemolyticus and further research is necessitated to fully understand its function in V. parahaemolyticus.
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Affiliation(s)
- Wenxiu Zhu
- State Key Laboratory of Marine Food Processing and Safety Control, National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Jiaxiu Liu
- State Key Laboratory of Marine Food Processing and Safety Control, National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Yingying Zhang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Dongyun Zhao
- State Key Laboratory of Marine Food Processing and Safety Control, National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Shugang Li
- State Key Laboratory of Marine Food Processing and Safety Control, National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Hanzheng Dou
- State Key Laboratory of Marine Food Processing and Safety Control, National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Haisong Wang
- Liaoning Key Lab of Lignocellulose Chemistry and BioMaterials, Liaoning Collaborative Innovation Center for Lignocellulosic Biorefinery, College of Light Industry and Chemical Engineering, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Xiaodong Xia
- State Key Laboratory of Marine Food Processing and Safety Control, National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China.
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3
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McCaughey C, Trebino MA, McAtamney A, Isenberg RY, Mandel MJ, Yildiz FH, Sanchez LM. A Label-Free Approach for Relative Spatial Quantitation of c-di-GMP in Microbial Biofilms. Anal Chem 2024; 96:8308-8316. [PMID: 38752543 PMCID: PMC11140670 DOI: 10.1021/acs.analchem.3c04687] [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: 10/17/2023] [Revised: 04/27/2024] [Accepted: 05/07/2024] [Indexed: 05/19/2024]
Abstract
Microbial biofilms represent an important lifestyle for bacteria and are dynamic three-dimensional structures. Cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous signaling molecule that is known to be tightly regulated with biofilm processes. While measurements of global levels of c-di-GMP have proven valuable toward understanding the genetic control of c-di-GMP production, there is a need for tools to observe the local changes of c-di-GMP production in biofilm processes. We have developed a label-free method for the direct detection of c-di-GMP in microbial colony biofilms using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). We applied this method to the enteric pathogen Vibrio cholerae, the marine symbiont V. fischeri, and the opportunistic pathogen Pseudomonas aeruginosa PA14 and detected spatial and temporal changes in c-di-GMP signal that accompanied genetic alterations in factors that synthesize and degrade the compound. We further demonstrated how this method can be simultaneously applied to detect additional metabolites of interest from a single sample.
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Affiliation(s)
- Catherine
S. McCaughey
- Department
of Chemistry and Biochemistry, University
of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Michael A. Trebino
- Department
of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Allyson McAtamney
- Department
of Chemistry and Biochemistry, University
of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Ruth Y. Isenberg
- Department
of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Microbiology
Doctoral Training Program, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Mark J. Mandel
- Department
of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Microbiology
Doctoral Training Program, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Fitnat H. Yildiz
- Department
of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Laura M. Sanchez
- Department
of Chemistry and Biochemistry, University
of California, Santa Cruz, Santa Cruz, California 95064, United States
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4
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Shao L, Shen Z, Li M, Guan C, Fan B, Chai Y, Zhao Y. ccdC Regulates Biofilm Dispersal in Bacillus velezensis FZB42. Int J Mol Sci 2024; 25:5201. [PMID: 38791239 PMCID: PMC11120784 DOI: 10.3390/ijms25105201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/30/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024] Open
Abstract
Bacillus velezensis FZB42 is a plant growth-promoting rhizobacterium (PGPR) and a model microorganism for biofilm studies. Biofilms are required for the colonization and promotion of plant growth in the rhizosphere. However, little is known about how the final stage of the biofilm life cycle is regulated, when cells regain their motility and escape the mature biofilm to spread and colonize new niches. In this study, the non-annotated gene ccdC was found to be involved in the process of biofilm dispersion. We found that the ccdC-deficient strain maintained a wrinkled state at the late stage of biofilm formation in the liquid-gas interface culture, and the bottom solution showed a clear state, indicating that no bacterial cells actively escaped, which was further evidenced by the formation of a cellular ring (biofilm pellicle) located on top of the preformed biofilm. It can be concluded that dispersal, a biofilm property that relies on motility proficiency, is also positively affected by the unannotated gene ccdC. Furthermore, we found that the level of cyclic diguanylate (c-di-GMP) in the ccdC-deficient strain was significantly greater than that in the wild-type strain, suggesting that B. velezensis exhibits a similar mechanism by regulating the level of c-di-GMP, the master regulator of biofilm formation, dispersal, and cell motility, which controls the fitness of biofilms in Pseudomonas aeruginosain. In this study, we investigated the mechanism regulating biofilm dispersion in PGPR.
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Affiliation(s)
- Lin Shao
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
- College of Life Science, Nanjing Forestry University, Nanjing 210037, China
| | - Zizhu Shen
- College of Life Science, Nanjing Forestry University, Nanjing 210037, China
| | - Meiju Li
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
| | - Chenyun Guan
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
| | - Ben Fan
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
- College of Life Science, Nanjing Forestry University, Nanjing 210037, China
| | - Yunrong Chai
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Yinjuan Zhao
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
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5
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Coppinger MN, Laramore K, Popham DL, Stabb EV. A prototrophic suppressor of a Vibrio fischeri D-glutamate auxotroph reveals a member of the periplasmic broad-spectrum racemase family (BsrF). J Bacteriol 2024; 206:e0033323. [PMID: 38411059 PMCID: PMC10955857 DOI: 10.1128/jb.00333-23] [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: 12/08/2023] [Accepted: 02/04/2024] [Indexed: 02/28/2024] Open
Abstract
Although bacterial peptidoglycan (PG) is highly conserved, some natural variations in PG biosynthesis and structure have evolved. Understanding the mechanisms and limits of such variation will inform our understanding of antibiotic resistance, innate immunity, and the evolution of bacteria. We have explored the constraints on PG evolution by blocking essential steps in PG biosynthesis in Vibrio fischeri and then selecting mutants with restored prototrophy. Here, we attempted to select prototrophic suppressors of a D-glutamate auxotrophic murI racD mutant. No suppressors were isolated on unsupplemented lysogeny broth salts (LBS), despite plating >1011 cells, nor were any suppressors generated through mutagenesis with ethyl methanesulfonate. A single suppressor was isolated on LBS supplemented with iso-D-gln, although the iso-D-gln subsequently appeared irrelevant. This suppressor has a genomic amplification formed by the creation of a novel junction that fuses proB to a gene encoding a putative broad-spectrum racemase of V. fischeri, bsrF. An engineered bsrF allele lacking the putative secretion signal (ΔSS-bsrF) also suppressed D-glu auxotrophy, resulting in PG that was indistinguishable from the wild type. The ΔSS-bsrF allele similarly suppressed the D-alanine auxotrophy of an alr mutant and restored prototrophy to a murI alr double mutant auxotrophic for both D-ala and D-glu. The ΔSS-bsrF allele increased resistance to D-cycloserine but had no effect on sensitivity to PG-targeting antibiotics penicillin, ampicillin, or vancomycin. Our work helps define constraints on PG evolution and reveals a periplasmic broad-spectrum racemase in V. fischeri that can be co-opted for PG biosynthesis, with concomitant D-cycloserine resistance. IMPORTANCE D-Amino acids are used and produced by organisms across all domains of life, but often, their origins and roles are not well understood. In bacteria, D-ala and D-glu are structural components of the canonical peptidoglycan cell wall and are generated by dedicated racemases Alr and MurI, respectively. The more recent discovery of additional bacterial racemases is broadening our view and deepening our understanding of D-amino acid metabolism. Here, while exploring alternative PG biosynthetic pathways in Vibrio fischeri, we unexpectedly shed light on an unusual racemase, BsrF. Our results illustrate a novel mechanism for the evolution of antibiotic resistance and provide a new avenue for exploring the roles of non-canonical racemases and D-amino acids in bacteria.
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Affiliation(s)
- Macey N. Coppinger
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
- Department of Biological Sciences, University of Illinois, Chicago, Illinois, USA
| | - Kathrin Laramore
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - David L. Popham
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Eric V. Stabb
- Department of Biological Sciences, University of Illinois, Chicago, Illinois, USA
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6
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Fung BL, Esin JJ, Visick KL. Vibrio fischeri: a model for host-associated biofilm formation. J Bacteriol 2024; 206:e0037023. [PMID: 38270381 PMCID: PMC10882983 DOI: 10.1128/jb.00370-23] [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] [Indexed: 01/26/2024] Open
Abstract
Multicellular communities of adherent bacteria known as biofilms are often detrimental in the context of a human host, making it important to study their formation and dispersal, especially in animal models. One such model is the symbiosis between the squid Euprymna scolopes and the bacterium Vibrio fischeri. Juvenile squid hatch aposymbiotically and selectively acquire their symbiont from natural seawater containing diverse environmental microbes. Successful pairing is facilitated by ciliary movements that direct bacteria to quiet zones on the surface of the squid's symbiotic light organ where V. fischeri forms a small aggregate or biofilm. Subsequently, the bacteria disperse from that aggregate to enter the organ, ultimately reaching and colonizing deep crypt spaces. Although transient, aggregate formation is critical for optimal colonization and is tightly controlled. In vitro studies have identified a variety of polysaccharides and proteins that comprise the extracellular matrix. Some of the most well-characterized matrix factors include the symbiosis polysaccharide (SYP), cellulose polysaccharide, and LapV adhesin. In this review, we discuss these components, their regulation, and other less understood V. fischeri biofilm contributors. We also highlight what is currently known about dispersal from these aggregates and host cues that may promote it. Finally, we briefly describe discoveries gleaned from the study of other V. fischeri isolates. By unraveling the complexities involved in V. fischeri's control over matrix components, we may begin to understand how the host environment triggers transient biofilm formation and dispersal to promote this unique symbiotic relationship.
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Affiliation(s)
- Brittany L. Fung
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jeremy J. Esin
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Karen L. Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
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Benhadda F, Zykwinska A, Colliec-Jouault S, Sinquin C, Thollas B, Courtois A, Fuzzati N, Toribio A, Delbarre-Ladrat C. Marine versus Non-Marine Bacterial Exopolysaccharides and Their Skincare Applications. Mar Drugs 2023; 21:582. [PMID: 37999406 PMCID: PMC10672628 DOI: 10.3390/md21110582] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/02/2023] [Accepted: 11/05/2023] [Indexed: 11/25/2023] Open
Abstract
Bacteria are well-known to synthesize high molecular weight polysaccharides excreted in extracellular domain, which constitute their protective microenvironment. Several bacterial exopolysaccharides (EPS) are commercially available for skincare applications in cosmetic products due to their unique structural features, conferring valuable biological and/or textural properties. This review aims to give an overview of bacterial EPS, an important group of macromolecules used in cosmetics as actives and functional ingredients. For this purpose, the main chemical characteristics of EPS are firstly described, followed by the basics of the development of cosmetic ingredients. Then, a focus on EPS production, including upstream and downstream processes, is provided. The diversity of EPS used in the cosmetic industry, and more specifically of marine-derived EPS is highlighted. Marine bacteria isolated from extreme environments are known to produce EPS. However, their production processes are highly challenging due to high or low temperatures; yield must be improved to reach economically viable ingredients. The biological properties of marine-derived EPS are then reviewed, resulting in the highlight of the challenges in this field.
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Affiliation(s)
- Fanny Benhadda
- Ifremer, MASAE Microbiologie Aliment Santé Environnement, F-44000 Nantes, France; (F.B.); (S.C.-J.); (C.S.); (C.D.-L.)
- CHANEL Fragrance and Beauty, F-93500 Pantin, France; (N.F.); (A.T.)
| | - Agata Zykwinska
- Ifremer, MASAE Microbiologie Aliment Santé Environnement, F-44000 Nantes, France; (F.B.); (S.C.-J.); (C.S.); (C.D.-L.)
| | - Sylvia Colliec-Jouault
- Ifremer, MASAE Microbiologie Aliment Santé Environnement, F-44000 Nantes, France; (F.B.); (S.C.-J.); (C.S.); (C.D.-L.)
| | - Corinne Sinquin
- Ifremer, MASAE Microbiologie Aliment Santé Environnement, F-44000 Nantes, France; (F.B.); (S.C.-J.); (C.S.); (C.D.-L.)
| | | | | | - Nicola Fuzzati
- CHANEL Fragrance and Beauty, F-93500 Pantin, France; (N.F.); (A.T.)
| | - Alix Toribio
- CHANEL Fragrance and Beauty, F-93500 Pantin, France; (N.F.); (A.T.)
| | - Christine Delbarre-Ladrat
- Ifremer, MASAE Microbiologie Aliment Santé Environnement, F-44000 Nantes, France; (F.B.); (S.C.-J.); (C.S.); (C.D.-L.)
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McCaughey CS, Trebino MA, McAtamney A, Isenberg R, Mandel MJ, Yildiz FH, Sanchez LM. A label-free approach for relative spatial quantitation of c-di-GMP in microbial biofilms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.10.561783. [PMID: 37873360 PMCID: PMC10592747 DOI: 10.1101/2023.10.10.561783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Microbial biofilms represent an important lifestyle for bacteria and are dynamic three dimensional structures. Cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous signaling molecule that is known to be tightly regulated with biofilm processes. While measurements of global levels of c-di-GMP have proven valuable towards understanding the genetic control of c-di-GMP production, there is a need for tools to observe the local changes of c-di-GMP production in biofilm processes. We have developed a label-free method for the direct detection of c-di-GMP in microbial colony biofilms using matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI). We applied this method to the enteric pathogen Vibrio cholerae, the marine symbiont V. fischeri, and the opportunistic pathogen Pseudomonas aeruginosa PA14 and detected spatial and temporal changes in c-di-GMP signal that accompanied genetic alterations in factors that synthesize and degrade the compound. We further demonstrated how this method can be simultaneously applied to detect additional metabolites of interest in a single experiment.
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Affiliation(s)
- Catherine S McCaughey
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Michael A Trebino
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Allyson McAtamney
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Ruth Isenberg
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706
- Current Address: Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Mark J Mandel
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706
| | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Laura M Sanchez
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064
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Speare L, Jackson A, Septer AN. Calcium Promotes T6SS-Mediated Killing and Aggregation between Competing Symbionts. Microbiol Spectr 2022; 10:e0139722. [PMID: 36453912 PMCID: PMC9769598 DOI: 10.1128/spectrum.01397-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 11/05/2022] [Indexed: 12/03/2022] Open
Abstract
Bacteria use a variety of strategies to exclude competitors from accessing resources, including space within a host niche. Because these mechanisms are typically costly to deploy, they are often tightly regulated for use in environments where the benefits outweigh the energetic cost. The type VI secretion system (T6SS) is a competitive mechanism that allows inhibitors to kill competing microbes by physically puncturing and translocating cytotoxic effectors directly into neighboring competitor cells. Although T6SSs are encoded in both symbiotic and free-living taxa where they may be actively secreting into the extracellular milieu during growth in liquid culture, there is little evidence for bacteria engaging in T6SS-mediated, contact-dependent killing under low-viscosity liquid conditions. Here, we determined that calcium acts as a pH-dependent cue to activate the assembly of an antibacterial T6SS in a Vibrio fischeri light organ symbiont in a low-viscosity liquid medium. Moreover, competing V. fischeri isolates formed mixed-strain aggregates that promoted the contact necessary for T6SS-dependent elimination of a target population. Our findings expand our knowledge of V. fischeri T6SS ecology and identify a low-viscosity liquid condition where cells engage in contact-dependent killing. IMPORTANCE Microbes deploy competitive mechanisms to gain access to resources such as nutrients or space within an ecological niche. Identifying when and where these strategies are employed can be challenging given the complexity and variability of most natural systems; therefore, studies evaluating specific cues that conditionally regulate interbacterial competition can inform the ecological context for such competition. In this work, we identified a pH-dependent chemical cue in seawater, calcium, which promotes activation of a contact-dependent interbacterial weapon in the marine symbiont Vibrio fischeri. This finding underscores the importance of using ecologically relevant salts in growth media and the ability of bacterial cells to sense and integrate multiple environmental cues to assess the need for a weapon. Identification of these cues provides insight into the types of environments where employing a weapon is advantageous to the survival and propagation of a bacterial population.
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Affiliation(s)
- Lauren Speare
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA
- Department of Microbiology, Oregon State University, Corvallis, Oregon, USA
| | - Aundre Jackson
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Alecia N. Septer
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA
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10
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Conserved FimK Truncation Coincides with Increased Expression of Type 3 Fimbriae and Cultured Bladder Epithelial Cell Association in Klebsiella quasipneumoniae. J Bacteriol 2022; 204:e0017222. [PMID: 36005809 PMCID: PMC9487511 DOI: 10.1128/jb.00172-22] [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] [Indexed: 11/20/2022] Open
Abstract
Klebsiella spp. commonly cause both uncomplicated urinary tract infection (UTI) and recurrent UTI (rUTI). Klebsiella quasipneumoniae, a relatively newly defined species of Klebsiella, has been shown to be metabolically distinct from Klebsiella pneumoniae, but its type 1 and type 3 fimbriae have not been studied. K. pneumoniae uses both type 1 and type 3 fimbriae to attach to host epithelial cells. The type 1 fimbrial operon is well conserved between Escherichia coli and K. pneumoniae apart from fimK, which is unique to Klebsiella spp. FimK contains an N-terminal DNA binding domain and a C-terminal phosphodiesterase (PDE) domain that has been hypothesized to cross-regulate type 3 fimbriae expression via modulation of cellular levels of cyclic di-GMP. Here, we find that a conserved premature stop codon in K. quasipneumoniae fimK results in truncation of the C-terminal PDE domain and that K quasipneumoniae strain KqPF9 cultured bladder epithelial cell association and invasion are dependent on type 3 but not type 1 fimbriae. Further, we show that basal expression of both type 1 and type 3 fimbrial operons as well as cultured bladder epithelial cell association is elevated in KqPF9 relative to uropathogenic K. pneumoniae TOP52. Finally, we show that complementation of KqPF9ΔfimK with the TOP52 fimK allele reduced type 3 fimbrial expression and cultured bladder epithelial cell attachment. Taken together these data suggest that the C-terminal PDE of FimK can modulate type 3 fimbrial expression in K. pneumoniae and its absence in K. quasipneumoniae may lead to a loss of type 3 fimbrial cross-regulation. IMPORTANCE K. quasipneumoniae is often indicated as the cause of opportunistic infections, including urinary tract infection, which affects >50% of women worldwide. However, the virulence factors of K. quasipneumoniae remain uninvestigated. Prior to this work, K. quasipneumoniae and K. pneumoniae had only been distinguished phenotypically by metabolic differences. This work contributes to the understanding of K. quasipneumoniae by evaluating the contribution of type 1 and type 3 fimbriae, which are critical colonization factors encoded by all Klebsiella spp., to K. quasipneumoniae bladder epithelial cell attachment in vitro. We observe clear differences in bladder epithelial cell attachment and regulation of type 3 fimbriae between uropathogenic K. pneumoniae and K. quasipneumoniae that coincide with a structural difference in the fimbrial regulatory gene fimK.
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11
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Liu PX, Zhang XY, Wang Q, Li YY, Sun WD, Qi Y, Zhou K, Han XG, Chen ZG, Fang WH, Jiang W. Biological and transcriptional studies reveal VmeL is involved in motility, biofilm formation and virulence in Vibrio parahaemolyticus. Front Microbiol 2022; 13:976334. [PMID: 36016795 PMCID: PMC9397117 DOI: 10.3389/fmicb.2022.976334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 07/19/2022] [Indexed: 11/25/2022] Open
Abstract
Vibrio parahaemolyticus is a marine pathogen thought to be the leading cause of seafood-borne gastroenteritis globally, urgently requiring efficient management methods. V. parahaemolyticus encodes 12 resistance/nodulation/division (RND) efflux systems. However, research on these systems is still in its infancy. In this study, we discovered that the inactivation of VmeL, a membrane fusion protein within the RND efflux systems, led to reduction of the ability of biofilm formation. Further results displayed that the decreased capacity of Congo red binding and the colony of ΔvmeL is more translucent compared with wild type strains, suggested reduced biofilm formation due to decreased production of biofilm exopolysaccharide upon vmeL deletion. In addition, the deletion of vmeL abolished surface swarming and swimming motility of V. parahaemolyticus. Additionally, deletion of vmeL weakened the cytotoxicity of V. parahaemolyticus towards HeLa cells, and impaired its virulence in a murine intraperitoneal infection assay. Finally, through RNA-sequencing, we ascertained that there were 716 upregulated genes and 247 downregulated genes in ΔvmeL strain. KEGG enrichment analysis revealed that quorum sensing, bacterial secretion systems, ATP-binding cassette transporters, and various amino acid metabolism pathways were altered due to the inactivation of vmeL. qRT-PCR further confirmed that genes accountable to the type III secretion system (T3SS1) and lateral flagella were negatively affected by vmeL deletion. Taken together, our results suggest that VmeL plays an important role in pathogenicity, making it a good target for managing infection with V. parahaemolyticus.
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Affiliation(s)
- Peng-xuan Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xiao-yun Zhang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Quan Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Yang-yang Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Wei-dong Sun
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yu Qi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Kai Zhou
- Shenzhen Institute of Respiratory Diseases, The First Affiliated Hospital (Shenzhen People’s Hospital), Shenzhen, China
| | - Xian-gan Han
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Zhao-guo Chen
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Wei-huan Fang
- Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
| | - Wei Jiang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
- *Correspondence: Wei Jiang,
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12
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Abstract
During colonization of the Hawaiian bobtail squid (Euprymna scolopes), Vibrio fischeri bacteria undergo a lifestyle transition from a planktonic motile state in the environment to a biofilm state in host mucus. Cyclic diguanylate (c-di-GMP) is a cytoplasmic signaling molecule that is important for regulating motility-biofilm transitions in many bacterial species. V. fischeri encodes 50 proteins predicted to synthesize and/or degrade c-di-GMP, but a role for c-di-GMP regulation during host colonization has not been investigated. We examined strains exhibiting either low or high levels of c-di-GMP during squid colonization and found that while a low-c-di-GMP strain had no colonization defect, a high c-di-GMP strain was severely impaired. Expression of a heterologous c-di-GMP phosphodiesterase restored colonization, demonstrating that the effect is due to high c-di-GMP levels. In the constitutive high-c-di-GMP state, colonizing V. fischeri exhibited reduced motility, altered biofilm aggregate morphology, and a regulatory interaction where transcription of one polysaccharide locus is inhibited by the presence of the other polysaccharide. Our results highlight the importance of proper c-di-GMP regulation during beneficial animal colonization, illustrate multiple pathways regulated by c-di-GMP in the host, and uncover an interplay of multiple exopolysaccharide systems in host-associated aggregates.
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13
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Shrestha P, Razvi A, Fung BL, Eichinger SJ, Visick KL. Mutational Analysis of Vibrio fischeri c-di-GMP-Modulating Genes Reveals Complex Regulation of Motility. J Bacteriol 2022; 204:e0010922. [PMID: 35758751 PMCID: PMC9295575 DOI: 10.1128/jb.00109-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 06/04/2022] [Indexed: 12/30/2022] Open
Abstract
The symbiont Vibrio fischeri uses motility to colonize its host. In numerous bacterial species, motility is negatively controlled by cyclic-di-GMP (c-di-GMP), which is produced by diguanylate cyclases (DGCs) with GGDEF domains and degraded by phosphodiesterases with either EAL or HD-GYP domains. To begin to decode the functions of the 50 Vibrio fischeri genes with GGDEF, EAL, and/or HD-GYP domains, we deleted each gene and assessed each mutant's migration through tryptone broth salt (TBS) soft agar medium containing or lacking magnesium (Mg) and calcium (Ca), which are known to influence V. fischeri motility. We identified 6, 13, and 16 mutants with altered migration in TBS-Mg, TBS, and TBS-Ca soft agar, respectively, a result that underscores the importance of medium conditions in assessing gene function. A biosensor-based assay revealed that Mg and Ca affected c-di-GMP levels negatively and positively, respectively; the severe decrease in c-di-GMP caused by Mg addition correlates with its strong positive impact on bacterial migration. A mutant defective for VF_0494, a homolog of V. cholerae rocS, exhibited a severe defect in migration across all conditions. Motility of a VF_1603 VF_2480 double mutant was also severely defective and could be restored by expression of "c-di-GMP-blind" alleles of master flagellar regulator flrA. Together, this work sheds light on the genes and conditions that influence c-di-GMP-mediated control over motility in V. fischeri and provides a foundation for (i) assessing roles of putative c-di-GMP-binding proteins, (ii) evaluating other c-di-GMP-dependent phenotypes in V. fischeri, (iii) uncovering potential redundancy, and (iv) deciphering signal transduction mechanisms. IMPORTANCE Critical bacterial processes, including motility, are influenced by c-di-GMP, which is controlled by environment-responsive synthetic and degradative enzymes. Because bacteria such as Vibrio fischeri use motility to colonize their hosts, understanding the roles of c-di-GMP-modulating enzymes in controlling motility has the potential to inform on microbe-host interactions. We leveraged recent advances in genetic manipulation to generate 50 mutants defective for putative c-di-GMP synthetic and degradative enzymes. We then assessed the consequences on motility, manipulating levels of magnesium and calcium, which inversely influenced motility and levels of c-di-GMP. Distinct subsets of the 50 genes were required under the different conditions. Our data thus provide needed insight into the functions of these enzymes and environmental factors that influence them.
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Affiliation(s)
| | - Ali Razvi
- Loyola University Chicago, Maywood, Illinois, USA
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14
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Lamprokostopoulou A, Römling U. Yin and Yang of Biofilm Formation and Cyclic di-GMP Signaling of the Gastrointestinal Pathogen Salmonella enterica Serovar Typhimurium. J Innate Immun 2021; 14:275-292. [PMID: 34775379 PMCID: PMC9275015 DOI: 10.1159/000519573] [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: 05/17/2021] [Accepted: 08/27/2021] [Indexed: 11/24/2022] Open
Abstract
Within the last 60 years, microbiological research has challenged many dogmas such as bacteria being unicellular microorganisms directed by nutrient sources; these investigations produced new dogmas such as cyclic diguanylate monophosphate (cyclic di-GMP) second messenger signaling as a ubiquitous regulator of the fundamental sessility/motility lifestyle switch on the single-cell level. Successive investigations have not yet challenged this view; however, the complexity of cyclic di-GMP as an intracellular bacterial signal, and, less explored, as an extracellular signaling molecule in combination with the conformational flexibility of the molecule, provides endless opportunities for cross-kingdom interactions. Cyclic di-GMP-directed microbial biofilms commonly stimulate the immune system on a lower level, whereas host-sensed cyclic di-GMP broadly stimulates the innate and adaptive immune responses. Furthermore, while the intracellular second messenger cyclic di-GMP signaling promotes bacterial biofilm formation and chronic infections, oppositely, Salmonella Typhimurium cellulose biofilm inside immune cells is not endorsed. These observations only touch on the complexity of the interaction of biofilm microbial cells with its host. In this review, we describe the Yin and Yang interactive concepts of biofilm formation and cyclic di-GMP signaling using S. Typhimurium as an example.
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Affiliation(s)
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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15
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Calcium-Responsive Diguanylate Cyclase CasA Drives Cellulose-Dependent Biofilm Formation and Inhibits Motility in Vibrio fischeri. mBio 2021; 12:e0257321. [PMID: 34749532 PMCID: PMC8576532 DOI: 10.1128/mbio.02573-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The marine bacterium Vibrio fischeri colonizes its host, the Hawaiian bobtail squid, in a manner requiring both bacterial biofilm formation and motility. The decision to switch between sessile and motile states is often triggered by environmental signals and regulated by the widespread signaling molecule c-di-GMP. Calcium is an environmental signal previously shown to affect both biofilm formation and motility by V. fischeri. In this study, we investigated the link between calcium and c-di-GMP, determining that calcium increases intracellular c-di-GMP dependent on a specific diguanylate cyclase, calcium-sensing protein A (CasA). CasA is activated by calcium, dependent on residues in an N-terminal sensory domain, and synthesizes c-di-GMP through an enzymatic C-terminal domain. CasA is responsible for calcium-dependent inhibition of motility and activation of cellulose-dependent biofilm formation. Calcium regulates cellulose biofilms at the level of transcription, which also requires the transcription factor VpsR. Finally, the Vibrio cholerae CasA homolog, CdgK, is unable to complement CasA and may be inhibited by calcium. Collectively, these results identify CasA as a calcium-responsive regulator, linking an external signal to internal decisions governing behavior, and shed light on divergence between Vibrio spp.
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16
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Para-Aminobenzoic Acid, Calcium, and c-di-GMP Induce Formation of Cohesive, Syp-Polysaccharide-Dependent Biofilms in Vibrio fischeri. mBio 2021; 12:e0203421. [PMID: 34607467 PMCID: PMC8546588 DOI: 10.1128/mbio.02034-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The marine bacterium Vibrio fischeri efficiently colonizes its symbiotic squid host, Euprymna scolopes, by producing a transient biofilm dependent on the symbiosis polysaccharide (SYP). In vitro, however, wild-type strain ES114 fails to form SYP-dependent biofilms. Instead, genetically engineered strains, such as those lacking the negative regulator BinK, have been developed to study this phenomenon. Historically, V. fischeri has been grown using LBS, a complex medium containing tryptone and yeast extract; supplementation with calcium is required to induce biofilm formation by a binK mutant. Here, through our discovery that yeast extract inhibits biofilm formation, we uncover signals and underlying mechanisms that control V. fischeri biofilm formation. In contrast to its inability to form a biofilm on unsupplemented LBS, a binK mutant formed cohesive, SYP-dependent colony biofilms on tTBS, modified LBS that lacks yeast extract. Moreover, wild-type strain ES114 became proficient to form cohesive, SYP-dependent biofilms when grown in tTBS supplemented with both calcium and the vitamin para-aminobenzoic acid (pABA); neither molecule alone was sufficient, indicating that this phenotype relies on coordinating two cues. pABA/calcium supplementation also inhibited bacterial motility. Consistent with these phenotypes, cells grown in tTBS with pABA/calcium were enriched in transcripts for biofilm-related genes and predicted diguanylate cyclases, which produce the second messenger cyclic-di-GMP (c-di-GMP). They also exhibited elevated levels of c-di-GMP, which was required for the observed phenotypes, as phosphodiesterase overproduction abrogated biofilm formation and partially rescued motility. This work thus provides insight into conditions, signals, and processes that promote biofilm formation by V. fischeri.
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17
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Abidi W, Torres-Sánchez L, Siroy A, Krasteva PV. Weaving of bacterial cellulose by the Bcs secretion systems. FEMS Microbiol Rev 2021; 46:6388354. [PMID: 34634120 PMCID: PMC8892547 DOI: 10.1093/femsre/fuab051] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 10/08/2021] [Indexed: 12/13/2022] Open
Abstract
Cellulose is the most abundant biological compound on Earth and while it is the predominant building constituent of plants, it is also a key extracellular matrix component in many diverse bacterial species. While bacterial cellulose was first described in the 19th century, it was not until this last decade that a string of structural works provided insights into how the cellulose synthase BcsA, assisted by its inner-membrane partner BcsB, senses c-di-GMP to simultaneously polymerize its substrate and extrude the nascent polysaccharide across the inner bacterial membrane. It is now established that bacterial cellulose can be produced by several distinct types of cellulose secretion systems and that in addition to BcsAB, they can feature multiple accessory subunits, often indispensable for polysaccharide production. Importantly, the last years mark significant progress in our understanding not only of cellulose polymerization per se but also of the bigger picture of bacterial signaling, secretion system assembly, biofilm formation and host tissue colonization, as well as of structural and functional parallels of this dominant biosynthetic process between the bacterial and eukaryotic domains of life. Here, we review current mechanistic knowledge on bacterial cellulose secretion with focus on the structure, assembly and cooperativity of Bcs secretion system components.
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Affiliation(s)
- Wiem Abidi
- 'Structural Biology of Biofilms' group, European Institute of Chemistry and Biology (IECB), F-33600 Pessac, France.,Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.,École doctorale 'Innovation thérapeutique: du fundamental à l'appliqué' (ITFA), Université Paris-Saclay, 92296, Chatenay-Malabry, France
| | - Lucía Torres-Sánchez
- 'Structural Biology of Biofilms' group, European Institute of Chemistry and Biology (IECB), F-33600 Pessac, France.,Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.,École doctorale 'Innovation thérapeutique: du fundamental à l'appliqué' (ITFA), Université Paris-Saclay, 92296, Chatenay-Malabry, France
| | - Axel Siroy
- 'Structural Biology of Biofilms' group, European Institute of Chemistry and Biology (IECB), F-33600 Pessac, France.,Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
| | - Petya Violinova Krasteva
- 'Structural Biology of Biofilms' group, European Institute of Chemistry and Biology (IECB), F-33600 Pessac, France.,Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
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18
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Morot A, El Fekih S, Bidault A, Le Ferrand A, Jouault A, Kavousi J, Bazire A, Pichereau V, Dufour A, Paillard C, Delavat F. Virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata involves both quorum sensing and a type III secretion system. Environ Microbiol 2021; 23:5273-5288. [PMID: 33989448 DOI: 10.1111/1462-2920.15592] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/15/2021] [Accepted: 05/08/2021] [Indexed: 02/05/2023]
Abstract
Environmental Vibrio strains represent a major threat in aquaculture, but the understanding of their virulence mechanisms heavily relies on the transposition of knowledge from human-pathogen vibrios. Here, the genetic bases of the virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata were characterized. We demonstrated that luxO, encoding a major regulator of the quorum sensing system, is crucial for the virulence of this strain, and that its deletion leads to a decrease in swimming motility, biofilm formation, and exopolysaccharide production. Furthermore, the biofilm formation by V. harveyi ORM4 was increased by abalone serum, which required LuxO. The absence of LuxO in V. harveyi ORM4 yielded opposite phenotypes compared with other Vibrio species including V. campbellii (still frequently named V. harveyi). In addition, we report a full type III secretion system (T3SS) gene cluster in the V. harveyi ORM4 genome. LuxO was shown to negatively regulate the promoter activity of exsA, encoding the major regulator of the T3SS genes, and the deletion of exsA abolished the virulence of V. harveyi ORM4. These results unveil virulence mechanisms set up by this environmentally important bacterial pathogen and pave the way for a better molecular understanding of the regulation of its pathogenicity.
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Affiliation(s)
- Amandine Morot
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
- Université de Bretagne-Sud, EA 3884, LBCM, IUEM, Lorient, France
| | | | | | | | - Albane Jouault
- Université de Bretagne-Sud, EA 3884, LBCM, IUEM, Lorient, France
| | - Javid Kavousi
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
| | - Alexis Bazire
- Université de Bretagne-Sud, EA 3884, LBCM, IUEM, Lorient, France
| | | | - Alain Dufour
- Université de Bretagne-Sud, EA 3884, LBCM, IUEM, Lorient, France
| | | | - François Delavat
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
- UMR CNRS 6286 UFIP, University of Nantes, Nantes, France
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19
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Dial CN, Eichinger SJ, Foxall R, Corcoran CJ, Tischler AH, Bolz RM, Whistler CA, Visick KL. Quorum Sensing and Cyclic di-GMP Exert Control Over Motility of Vibrio fischeri KB2B1. Front Microbiol 2021; 12:690459. [PMID: 34262549 PMCID: PMC8273514 DOI: 10.3389/fmicb.2021.690459] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/28/2021] [Indexed: 11/23/2022] Open
Abstract
Bacterial motility is critical for symbiotic colonization by Vibrio fischeri of its host, the squid Euprymna scolopes, facilitating movement from surface biofilms to spaces deep inside the symbiotic organ. While colonization has been studied traditionally using strain ES114, others, including KB2B1, can outcompete ES114 for colonization for a variety of reasons, including superior biofilm formation. We report here that KB2B1 also exhibits an unusual pattern of migration through a soft agar medium: whereas ES114 migrates rapidly and steadily, KB2B1 migrates slowly and then ceases migration. To better understand this phenomenon, we isolated and sequenced five motile KB2B1 suppressor mutants. One harbored a mutation in the gene for the cAMP receptor protein (crp); because this strain also exhibited a growth defect, it was not characterized further. Two other suppressors contained mutations in the quorum sensing pathway that controls bacterial bioluminescence in response to cell density, and two had mutations in the diguanylate cyclase (DGC) gene VF_1200. Subsequent analysis indicated that (1) the quorum sensing mutations shifted KB2B1 to a perceived low cell density state and (2) the high cell density state inhibited migration via the downstream regulator LitR. Similar to the initial point mutations, deletion of the VF_1200 DGC gene increased migration. Consistent with the possibility that production of the second messenger c-di-GMP inhibited the motility of KB2B1, reporter-based measurements of c-di-GMP revealed that KB2B1 produced higher levels of c-di-GMP than ES114, and overproduction of a c-di-GMP phosphodiesterase promoted migration of KB2B1. Finally, we assessed the role of viscosity in controlling the quorum sensing pathway using polyvinylpyrrolidone and found that viscosity increased light production of KB2B1 but not ES114. Together, our data indicate that while the two strains share regulators in common, they differ in the specifics of the regulatory control over downstream phenotypes such as motility.
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Affiliation(s)
- Courtney N. Dial
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, United States
| | - Steven J. Eichinger
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, United States
| | - Randi Foxall
- Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, United States
| | - Christopher J. Corcoran
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, United States
| | - Alice H. Tischler
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, United States
| | - Robert M. Bolz
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, United States
| | - Cheryl A. Whistler
- Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, United States
| | - Karen L. Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, United States
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20
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A lasting symbiosis: how Vibrio fischeri finds a squid partner and persists within its natural host. Nat Rev Microbiol 2021; 19:654-665. [PMID: 34089008 DOI: 10.1038/s41579-021-00557-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2021] [Indexed: 01/10/2023]
Abstract
As our understanding of the human microbiome progresses, so does the need for natural experimental animal models that promote a mechanistic understanding of beneficial microorganism-host interactions. Years of research into the exclusive symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and the bioluminescent bacterium Vibrio fischeri have permitted a detailed understanding of those bacterial genes underlying signal exchange and rhythmic activities that result in a persistent, beneficial association, as well as glimpses into the evolution of symbiotic competence. Migrating from the ambient seawater to regions deep inside the light-emitting organ of the squid, V. fischeri experiences, recognizes and adjusts to the changing environmental conditions. Here, we review key advances over the past 15 years that are deepening our understanding of these events.
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21
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Fidopiastis PM, Mariscal V, McPherson JM, McAnulty S, Dunn A, Stabb EV, Visick KL. Vibrio fischeri Amidase Activity Is Required for Normal Cell Division, Motility, and Symbiotic Competence. Appl Environ Microbiol 2021; 87:e02109-20. [PMID: 33187995 PMCID: PMC7848909 DOI: 10.1128/aem.02109-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/12/2020] [Indexed: 11/20/2022] Open
Abstract
N-Acetylmuramoyl-l-alanine amidases are periplasmic hydrolases that cleave the amide bond between N-acetylmuramic acid and alanine in peptidoglycan (PG). Unlike many Gram-negative bacteria that encode redundant periplasmic amidases, Vibrio fischeri appears to encode a single protein that is homologous to AmiB of Vibrio cholerae We screened a V. fischeri transposon mutant library for strains altered in biofilm production and discovered a biofilm-overproducing strain with an insertion in amiB (VF_2326). Further characterization of biofilm enhancement suggested that this phenotype was due to the overproduction of cellulose, and it was dependent on the bcsA cellulose synthase. Additionally, the amiB mutant was nonmotile, perhaps due to defects in its ability to septate during division. The amidase mutant was unable to compete with the wild type for the colonization of V. fischeri's symbiotic host, the squid Euprymna scolopes In single-strain inoculations, host squid inoculated with the mutant eventually became colonized but with a much lower efficiency than in squid inoculated with the wild type. This observation was consistent with the pleiotropic effects of the amiB mutation and led us to speculate that motile suppressors of the amiB mutant were responsible for the partially restored colonization. In culture, motile suppressor mutants carried point mutations in a single gene (VF_1477), resulting in a partial restoration of wild-type motility. In addition, these point mutations reversed the effect of the amiB mutation on cellulosic biofilm production. These data are consistent with V. fischeri AmiB possessing amidase activity; they also suggest that AmiB suppresses cellulosic biofilm formation but promotes successful host colonization.IMPORTANCE Peptidoglycan (PG) is a critical microbe-associated molecular pattern (MAMP) that is sloughed by cells of V. fischeri during symbiotic colonization of squid. Specifically, this process induces significant remodeling of a specialized symbiotic light organ within the squid mantle cavity. This phenomenon is reminiscent of the loss of ciliated epithelium in patients with whooping cough due to the production of PG monomers by Bordetella pertussis Furthermore, PG processing machinery can influence susceptibility to antimicrobials. In this study, we report roles for the V. fischeri PG amidase AmiB, including the beneficial colonization of squid, underscoring the urgency to more deeply understand PG processing machinery and the downstream consequences of their activities.
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Affiliation(s)
| | | | | | | | - Anne Dunn
- University of Oklahoma, Norman, Oklahoma, USA
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22
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Identification of a Transcriptomic Network Underlying the Wrinkly and Smooth Phenotypes of Vibrio fischeri. J Bacteriol 2021; 203:JB.00259-20. [PMID: 33199286 PMCID: PMC7811199 DOI: 10.1128/jb.00259-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 11/04/2020] [Indexed: 01/27/2023] Open
Abstract
Vibrio fischeri is a cosmopolitan marine bacterium that oftentimes displays different colony morphologies, switching from a smooth to a wrinkly phenotype in order to adapt to changes in the environment. This wrinkly phenotype has also been associated with increased biofilm formation, an essential characteristic for V. fischeri to adhere to substrates, to suspended debris, and within the light organs of sepiolid squids. Elevated levels of biofilm formation are correlated with increased microbial survival of exposure to environmental stressors and the ability to expand niche breadth. Since V. fischeri has a biphasic life history strategy between its free-living and symbiotic states, we were interested in whether the wrinkly morphotype demonstrated differences in its expression profile in comparison to the naturally occurring and more common smooth variant. We show that genes involved in major biochemical cascades, including those involved in protein sorting, oxidative stress, and membrane transport, play a role in the wrinkly phenotype. Interestingly, only a few unique genes are specifically involved in macromolecule biosynthesis in the wrinkly phenotype, which underlies the importance of other pathways utilized for adaptation under the conditions in which Vibrio bacteria are producing this change in phenotype. These results provide the first comprehensive analysis of the complex form of genetic activation that underlies the diversity in morphologies of V. fischeri when switching between two different colony morphotypes, each representing a unique biofilm ecotype.IMPORTANCE The wrinkly bacterial colony phenotype has been associated with increased squid host colonization in V. fischeri The significance of our research is in identifying the genetic mechanisms that are responsible for heightened biofilm formation in V. fischeri This report also advances our understanding of gene regulation in V. fischeri and brings to the forefront a number of previously overlooked genetic networks. Several loci that were identified in this study were not previously known to be associated with biofilm formation in V. fischeri.
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23
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Christensen DG, Marsden AE, Hodge-Hanson K, Essock-Burns T, Visick KL. LapG mediates biofilm dispersal in Vibrio fischeri by controlling maintenance of the VCBS-containing adhesin LapV. Mol Microbiol 2020; 114:742-761. [PMID: 32654271 DOI: 10.1111/mmi.14573] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 12/18/2022]
Abstract
Efficient symbiotic colonization of the squid Euprymna scolopes by the bacterium Vibrio fischeri depends on bacterial biofilm formation on the surface of the squid's light organ. Subsequently, the bacteria disperse from the biofilm via an unknown mechanism and enter through pores to reach the interior colonization sites. Here, we identify a homolog of Pseudomonas fluorescens LapG as a dispersal factor that promotes cleavage of a biofilm-promoting adhesin, LapV. Overproduction of LapG inhibited biofilm formation and, unlike the wild-type parent, a ΔlapG mutant formed biofilms in vitro. Although V. fischeri encodes two putative large adhesins, LapI (near lapG on chromosome II) and LapV (on chromosome I), only the latter contributed to biofilm formation. Consistent with the Pseudomonas Lap system model, our data support a role for the predicted c-di-GMP-binding protein LapD in inhibiting LapG-dependent dispersal. Furthermore, we identified a phosphodiesterase, PdeV, whose loss promotes biofilm formation similar to that of the ΔlapG mutant and dependent on both LapD and LapV. Finally, we found a minor defect for a ΔlapD mutant in initiating squid colonization, indicating a role for the Lap system in a relevant environmental niche. Together, these data reveal new factors and provide important insights into biofilm dispersal by V. fischeri.
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Affiliation(s)
- David G Christensen
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Anne E Marsden
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Kelsey Hodge-Hanson
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Tara Essock-Burns
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Karen L Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
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Narváez-Barragán DA, de Sandozequi A, Rodríguez M, Estrada K, Tovar-Herrera OE, Martínez-Anaya C. Analysis of two Mexican Pectobacterium brasiliense strains reveals an inverted relationship between c-di-GMP levels with exopolysaccharide production and swarming motility. Microbiol Res 2020; 235:126427. [PMID: 32109688 DOI: 10.1016/j.micres.2020.126427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 02/01/2020] [Accepted: 02/01/2020] [Indexed: 10/25/2022]
Abstract
Pectobacterium is a diverse genus of phytopathogenic species from soil and water that cause infection either to restricted or multiple plant hosts. Phylogenetic analysis and metabolic fingerprinting of large numbers of genomes have expanded classification of Pectobacterium members. Pectobacterium brasiliense sp. nov has been elevated to the species level having detached from P. carotovorum. Here we present two P. brasiliense strains BF20 and BF45 isolated in Mexico from Opuntia and tobacco, respectively, which cluster into two different groups in whole genome comparisons with other Pectobacterium. We found that BF20 and BF45 strains are phenotypically different as BF45 showed more severe and rapid symptoms in comparison to BF20 in the host models celery and broccoli. Both strains produced similar levels of the main autoinducers, but BF45 shows an additional low abundant autoinducer compared to strain BF20. The two strains had different levels of c-di-GMP, which regulates the transition from motile to sessile lifestyle. In contrast to BF45, BF20 had the highest levels of c-di-GMP, was more motile (swarming), non-flocculant and less proficient in biofilm formation and exopolysaccharide production. Genomic comparisons revealed that differences in c-di-GMP accumulation and perhaps the associated phenotypes might be due to unique c-di-GMP metabolic genes in these two strains. Our results improve our understanding of the associations between phenotype and genotype and how this has shaped the physiology of Pectobacterium strains.
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Affiliation(s)
- Delia A Narváez-Barragán
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, México
| | - Andrés de Sandozequi
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, México
| | - Mabel Rodríguez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, México
| | - Karel Estrada
- Unidad de Secuenciación Masiva y Bioinformática. Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, México
| | - Omar E Tovar-Herrera
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, México
| | - Claudia Martínez-Anaya
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, México.
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Soto W, Travisano M, Tolleson AR, Nishiguchi MK. Symbiont evolution during the free-living phase can improve host colonization. MICROBIOLOGY-SGM 2019; 165:174-187. [PMID: 30648935 PMCID: PMC7003651 DOI: 10.1099/mic.0.000756] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
For micro-organisms cycling between free-living and host-associated stages, where reproduction occurs in both of these lifestyles, an interesting inquiry is whether evolution during the free-living stage can be positively pleiotropic to microbial fitness in a host environment. To address this topic, the squid host Euprymna tasmanica and the marine bioluminescent bacterium Vibrio fischeri were utilized. Microbial ecological diversification in static liquid microcosms was used to simulate symbiont evolution during the free-living stage. Thirteen genetically distinct V. fischeri strains from a broad diversity of ecological sources (e.g. squid light organs, fish light organs and seawater) were examined to see if the results were reproducible in many different genetic settings. Genetic backgrounds that are closely related can be predisposed to considerable differences in how they respond to similar selection pressures. For all strains examined, new mutations with striking and facilitating effects on host colonization arose quickly during microbial evolution in the free-living stage, regardless of the ecological context under consideration for a strain’s genetic background. Microbial evolution outside a host environment promoted host range expansion, improved host colonization for a micro-organism, and diminished the negative correlation between biofilm formation and motility.
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Affiliation(s)
- William Soto
- 1College of William & Mary, Department of Biology, Integrated Science Center Rm 3035, 540 Landrum Dr Williamsburg, VA 23185, USA
| | - Michael Travisano
- 2Department of Ecology, Evolution, and Behavior, University of Minnesota-Twin Cities, 100 Ecology Building, 1987 Upper Buford Circle, Saint Paul, MN 55108, USA.,3BioTechnology Institute, University of Minnesota-Twin Cities, 140 Gortner Labs, 1479 Gortner Avenue, St Paul, MN 55108, USA
| | - Alexandra Rose Tolleson
- 1College of William & Mary, Department of Biology, Integrated Science Center Rm 3035, 540 Landrum Dr Williamsburg, VA 23185, USA
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Mutagenesis of Vibrio fischeri and Other Marine Bacteria Using Hyperactive Mini-Tn5 Derivatives. Methods Mol Biol 2019; 2016:87-104. [PMID: 31197712 DOI: 10.1007/978-1-4939-9570-7_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mutagenizing bacterial genomes with selectable transposon insertions is an effective approach for identifying the genes underlying important phenotypes. Specific bacteria may require different tools and methods for effective transposon mutagenesis, and here we describe methods to mutagenize Vibrio fischeri using an engineered mini-Tn5 transposon with synthetic "mosaic" transposon ends. The transposon is delivered by conjugation on a plasmid that cannot replicate in V. fischeri and that encodes a hyperactive transposase outside the transposon itself. The chromosomal location of insertions can be readily identified by cloning and/or PCR-based methods described here. Although developed in V. fischeri, these tools and methods have proven effective in some other bacteria as well.
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Discovery of Calcium as a Biofilm-Promoting Signal for Vibrio fischeri Reveals New Phenotypes and Underlying Regulatory Complexity. J Bacteriol 2018; 200:JB.00016-18. [PMID: 29463601 DOI: 10.1128/jb.00016-18] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 02/09/2018] [Indexed: 11/20/2022] Open
Abstract
Vibrio fischeri uses biofilm formation to promote symbiotic colonization of its squid host, Euprymna scolopes Control over biofilm formation is exerted at the level of transcription of the symbiosis polysaccharide (syp) locus by a complex set of two-component regulators. Biofilm formation can be induced by overproduction of the sensor kinase RscS, which requires the activities of the hybrid sensor kinase SypF and the response regulator SypG and is negatively regulated by the sensor kinase BinK. Here, we identify calcium as a signal that promotes biofilm formation by biofilm-competent strains under conditions in which biofilms are not typically observed (growth with shaking). This was true for RscS-overproducing cells as well as for strains in which only the negative regulator binK was deleted. The latter results provided, for the first time, an opportunity to induce and evaluate biofilm formation without regulator overexpression. Using these conditions, we determined that calcium induces both syp-dependent and bacterial cellulose synthesis (bcs)-dependent biofilms at the level of transcription of these loci. The calcium-induced biofilms were dependent on SypF, but SypF's Hpt domain was sufficient for biofilm formation. These data suggested the involvement of another sensor kinase(s) and led to the discovery that both RscS and a previously uncharacterized sensor kinase, HahK, functioned in this pathway. Together, the data presented here reveal both a new signal and biofilm phenotype produced by V. fischeri cells, the coordinate production of two polysaccharides involved in distinct biofilm behaviors, and a new regulator that contributes to control over these processes.IMPORTANCE Biofilms, or communities of surface-attached microorganisms adherent via a matrix that typically includes polysaccharides, are highly resistant to environmental stresses and are thus problematic in the clinic and important to study. Vibrio fischeri forms biofilms to colonize its symbiotic host, making this organism useful for studying biofilms. Biofilm formation depends on the syp polysaccharide locus and its regulators. Here, we identify a signal, calcium, that induces both SYP-PS and cellulose-dependent biofilms. We also identify a new syp regulator, the sensor kinase HahK, and discover a mutant phenotype for the sensor kinase RscS. This work thus reveals a specific biofilm-inducing signal that coordinately controls two polysaccharides, identifies a new regulator, and clarifies the regulatory control over biofilm formation by V. fischeri.
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Tools for Rapid Genetic Engineering of Vibrio fischeri. Appl Environ Microbiol 2018; 84:AEM.00850-18. [PMID: 29776924 DOI: 10.1128/aem.00850-18] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 05/11/2018] [Indexed: 11/20/2022] Open
Abstract
Vibrio fischeri is used as a model for a number of processes, including symbiosis, quorum sensing, bioluminescence, and biofilm formation. Many of these studies depend on generating deletion mutants and complementing them. Engineering such strains, however, is a time-consuming, multistep process that relies on cloning and subcloning. Here, we describe a set of tools that can be used to rapidly engineer deletions and insertions in the V. fischeri chromosome without cloning. We developed a uniform approach for generating deletions using PCR splicing by overlap extension (SOEing) with antibiotic cassettes flanked by standardized linker sequences. PCR SOEing of the cassettes to sequences up- and downstream of the target gene generates a DNA product that can be directly introduced by natural transformation. Selection for the introduced antibiotic resistance marker yields the deletion of interest in a single step. Because these cassettes also contain FRT (FLP recognition target) sequences flanking the resistance marker, Flp recombinase can be used to generate an unmarked, in-frame deletion. We developed a similar methodology and tools for the rapid insertion of specific genes at a benign site in the chromosome for purposes such as complementation. Finally, we generated derivatives of these tools to facilitate different applications, such as inducible gene expression and assessing protein production. We demonstrated the utility of these tools by deleting and inserting genes known or predicted to be involved in motility. While developed for V. fischeri strain ES114, we anticipate that these tools can be adapted for use in other V. fischeri strains and, potentially, other microbes.IMPORTANCEVibrio fischeri is a model organism for studying a variety of important processes, including symbiosis, biofilm formation, and quorum sensing. To facilitate investigation of these biological mechanisms, we developed approaches for rapidly generating deletions and insertions and demonstrated their utility using two genes of interest. The ease, consistency, and speed of the engineering is facilitated by a set of antibiotic resistance cassettes with common linker sequences that can be amplified by PCR with universal primers and fused to adjacent sequences using splicing by overlap extension and then introduced directly into V. fischeri, eliminating the need for cloning and plasmid conjugation. The antibiotic cassettes are flanked by FRT sequences, permitting their removal using Flp recombinase. We augmented these basic tools with a family of constructs for different applications. We anticipate that these tools will greatly accelerate mechanistic studies of biological processes in V. fischeri and potentially other Vibrio species.
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Jung HI, Kim YJ, Lee YJ, Lee HS, Lee JK, Kim SK. Mutation of the cyclic di-GMP phosphodiesterase gene in Burkholderia lata SK875 attenuates virulence and enhances biofilm formation. J Microbiol 2017; 55:800-808. [PMID: 28956352 DOI: 10.1007/s12275-017-7374-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 09/14/2017] [Accepted: 09/17/2017] [Indexed: 12/11/2022]
Abstract
Burkholderia sp. is a gram-negative bacterium that commonly exists in the environment, and can cause diseases in plants, animals, and humans. Here, a transposon mutant library of a Burkholderia lata isolate from a pig with swine respiratory disease in Korea was screened for strains showing attenuated virulence in Caenorhabditis elegans. One such mutant was obtained, and the Tn5 insertion junction was mapped to rpfR, a gene encoding a cyclic di-GMP phosphodiesterase that functions as a receptor. Mutation of rpfR caused a reduction in growth on CPG agar and swimming motility as well as a rough colony morphology on Congo red agar. TLC analysis showed reduced AHL secretion, which was in agreement with the results from plate-based and bioluminescence assays. The mutant strain produced significantly more biofilm detected by crystal violet staining than the parent strain. SEM of the mutant strain clearly showed that the overproduced biofilm contained a filamentous structure. These results suggest that the cyclic di-GMP phosphodiesterase RpfR plays an important role in quorum sensing modulation of the bacterial virulence and biofilm formation.
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Affiliation(s)
- Hae-In Jung
- Department of Animal Science and Technology, Konkuk University, Seoul, 05029, Republic of Korea
| | - Yun-Jung Kim
- Department of Animal Science and Technology, Konkuk University, Seoul, 05029, Republic of Korea
| | - Yun-Jung Lee
- Department of Animal Science and Technology, Konkuk University, Seoul, 05029, Republic of Korea
| | - Hee-Soo Lee
- National Veterinary Research and Quarantine Service, Anyang, 14033, Republic of Korea
| | - Jung-Kee Lee
- Department of Life Science and Genetic Engineering, Paichai University, Daejeon, 35345, Republic of Korea
| | - Soo-Ki Kim
- Department of Animal Science and Technology, Konkuk University, Seoul, 05029, Republic of Korea.
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Pankey MS, Foxall RL, Ster IM, Perry LA, Schuster BM, Donner RA, Coyle M, Cooper VS, Whistler CA. Host-selected mutations converging on a global regulator drive an adaptive leap towards symbiosis in bacteria. eLife 2017; 6:e24414. [PMID: 28447935 PMCID: PMC5466423 DOI: 10.7554/elife.24414] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/23/2017] [Indexed: 01/14/2023] Open
Abstract
Host immune and physical barriers protect against pathogens but also impede the establishment of essential symbiotic partnerships. To reveal mechanisms by which beneficial organisms adapt to circumvent host defenses, we experimentally evolved ecologically distinct bioluminescent Vibrio fischeri by colonization and growth within the light organs of the squid Euprymna scolopes. Serial squid passaging of bacteria produced eight distinct mutations in the binK sensor kinase gene, which conferred an exceptional selective advantage that could be demonstrated through both empirical and theoretical analysis. Squid-adaptive binK alleles promoted colonization and immune evasion that were mediated by cell-associated matrices including symbiotic polysaccharide (Syp) and cellulose. binK variation also altered quorum sensing, raising the threshold for luminescence induction. Preexisting coordinated regulation of symbiosis traits by BinK presented an efficient solution where altered BinK function was the key to unlock multiple colonization barriers. These results identify a genetic basis for microbial adaptability and underscore the importance of hosts as selective agents that shape emergent symbiont populations.
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Affiliation(s)
- M Sabrina Pankey
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
| | - Randi L Foxall
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
| | - Ian M Ster
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
- Graduate Program in Biochemistry, University of New Hampshire, Durham, United States
| | - Lauren A Perry
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Graduate Program in Microbiology, University of New Hampshire, Durham, United States
| | - Brian M Schuster
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Rachel A Donner
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Matthew Coyle
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Graduate Program in Microbiology, University of New Hampshire, Durham, United States
| | - Vaughn S Cooper
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
| | - Cheryl A Whistler
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
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Sadiq FA, Flint S, Li Y, Liu T, Lei Y, Sakandar HA, He G. New mechanistic insights into the motile-to-sessile switch in various bacteria with particular emphasis on Bacillus subtilis and Pseudomonas aeruginosa: a review. BIOFOULING 2017; 33:306-326. [PMID: 28347177 DOI: 10.1080/08927014.2017.1304541] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/04/2017] [Indexed: 06/06/2023]
Abstract
A biofilm is a complex assemblage of microbial communities adhered to a biotic or an abiotic surface which is embedded within a self-produced matrix of extracellular polymeric substances. Many transcriptional regulators play a role in triggering a motile-sessile switch and in consequently producing the biofilm matrix. This review is aimed at highlighting the role of two nucleotide signaling molecules (c-di-GMP and c-di-AMP), toxin antitoxin modules and a novel transcriptional regulator BolA in biofilm formation in various bacteria. In addition, it highlights the common themes that have appeared in recent research regarding the key regulatory components and signal transduction pathways that help Bacillus subtilis and Pseudomonas aeruginosa to acquire the biofilm mode of life.
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Affiliation(s)
- Faizan A Sadiq
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | - Steve Flint
- b School of Food and Nutrition , Massey University , Palmerston North , New Zealand
| | - Yun Li
- c School of Life Sciences and Food Technology , Hanshan Normal University , Chaozhou , PR China
| | - TongJie Liu
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | - Yuan Lei
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | | | - GuoQing He
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
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Impact of Salt and Nutrient Content on Biofilm Formation by Vibrio fischeri. PLoS One 2017; 12:e0169521. [PMID: 28122010 PMCID: PMC5266276 DOI: 10.1371/journal.pone.0169521] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/19/2016] [Indexed: 11/19/2022] Open
Abstract
Vibrio fischeri, a marine bacterium and symbiont of the Hawaiian bobtail squid Euprymna scolopes, depends on biofilm formation for successful colonization of the squid’s symbiotic light organ. Here, we investigated if culture conditions, such as nutrient and salt availability, affect biofilm formation by V. fischeri by testing the formation of wrinkled colonies on solid media. We found that V. fischeri forms colonies with more substantial wrinkling when grown on the nutrient-dense LBS medium containing NaCl relative to those formed on the more nutrient-poor, seawater-salt containing SWT medium. The presence of both tryptone and yeast extract was necessary for the production of “normal” wrinkled colonies; when grown on tryptone alone, the colonies displayed a divoting phenotype and were attached to the agar surface. We also found that the type and concentration of specific seawater salts influenced the timing of biofilm formation. Of the conditions assayed, wrinkled colony formation occurred earliest in LBS(-Tris) media containing 425 mM NaCl, 35 mM MgSO4, and 5 mM CaCl2. Pellicle formation, another measure of biofilm development, was also enhanced in these growth conditions. Therefore, both nutrient and salt availability contribute to V. fischeri biofilm formation. While growth was unaffected, these optimized conditions resulted in increased syp locus expression as measured by a PsypA-lacZ transcriptional reporter. We anticipate these studies will help us understand how the natural environment of V. fischeri affects its ability to form biofilms and, ultimately, colonize E. scolopes.
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Ahmad I, Rouf SF, Sun L, Cimdins A, Shafeeq S, Le Guyon S, Schottkowski M, Rhen M, Römling U. BcsZ inhibits biofilm phenotypes and promotes virulence by blocking cellulose production in Salmonella enterica serovar Typhimurium. Microb Cell Fact 2016; 15:177. [PMID: 27756305 PMCID: PMC5070118 DOI: 10.1186/s12934-016-0576-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 10/03/2016] [Indexed: 02/04/2023] Open
Abstract
Background Cellulose, a 1,4 beta-glucan polysaccharide, is produced by a variety of organisms including bacteria. Although the production of cellulose has a high biological, ecological and economical impact, regulatory mechanisms of cellulose biosynthesis are mostly unknown. Family eight cellulases are regularly associated with cellulose biosynthesis operons in bacteria; however, their function is poorly characterized. In this study, we analysed the role of the cellulase BcsZ encoded by the bcsABZC cellulose biosynthesis operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) in biofilm related behavior. We also investigated the involvement of BcsZ in pathogenesis of S. Typhimurium including a murine typhoid fever infection model. Result In S. Typhimurium, cellulase BcsZ with a putative periplasmic location negatively regulates cellulose biosynthesis. Moreover, as assessed with a non-polar mutant, BcsZ affects cellulose-associated phenotypes such as the rdar biofilm morphotype, cell clumping, biofilm formation, pellicle formation and flagella-dependent motility. Strikingly, although upregulation of cellulose biosynthesis was not observed on agar plate medium at 37 °C, BcsZ is required for efficient pathogen-host interaction. Key virulence phenotypes of S. Typhimurium such as invasion of epithelial cells and proliferation in macrophages were positively regulated by BcsZ. Further on, a bcsZ mutant was outcompeted by the wild type in organ colonization in the murine typhoid fever infection model. Selected phenotypes were relieved upon deletion of the cellulose synthase BcsA and/or the central biofilm activator CsgD. Conclusion Although the protein scaffold has an additional physiological role, our findings indicate that the catalytic activity of BcsZ effectively downregulates CsgD activated cellulose biosynthesis. Repression of cellulose production by BcsZ subsequently enables Salmonella to efficiently colonize the host. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0576-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Irfan Ahmad
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Syed Fazle Rouf
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Quebec, Canada
| | - Lei Sun
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Annika Cimdins
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Sulman Shafeeq
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Soazig Le Guyon
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Marco Schottkowski
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Mikael Rhen
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
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The Histidine Kinase BinK Is a Negative Regulator of Biofilm Formation and Squid Colonization. J Bacteriol 2016; 198:2596-607. [PMID: 26977108 PMCID: PMC5019070 DOI: 10.1128/jb.00037-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/29/2016] [Indexed: 11/22/2022] Open
Abstract
Bacterial colonization of animal epithelial tissue is a dynamic process that relies on precise molecular communication. Colonization of Euprymna scolopes bobtail squid by Vibrio fischeri bacteria requires bacterial aggregation in host mucus as the symbiont transitions from a planktonic lifestyle in seawater to a biofilm-associated state in the host. We have identified a gene, binK (biofilm inhibitor kinase; VF_A0360), which encodes an orphan hybrid histidine kinase that negatively regulates the V. fischeri symbiotic biofilm (Syp) in vivo and in vitro. We identified binK mutants as exhibiting a colonization advantage in a global genetic screen, a phenotype that we confirmed in controlled competition experiments. Bacterial biofilm aggregates in the host are larger in strains lacking BinK, whereas overexpression of BinK suppresses biofilm formation and squid colonization. Signaling through BinK is required for temperature modulation of biofilm formation at 28°C. Furthermore, we present evidence that BinK acts upstream of SypG, the σ54-dependent transcriptional regulator of the syp biofilm locus. The BinK effects are dependent on intact signaling in the RscS-Syp biofilm pathway. Therefore, we propose that BinK antagonizes the signal from RscS and serves as an integral component in V. fischeri biofilm regulation. IMPORTANCE Bacterial lifestyle transitions underlie the colonization of animal hosts from environmental reservoirs. Formation of matrix-enclosed, surface-associated aggregates (biofilms) is common in beneficial and pathogenic associations, but investigating the genetic basis of biofilm development in live animal hosts remains a significant challenge. Using the bobtail squid light organ as a model, we analyzed putative colonization factors and identified a histidine kinase that negatively regulates biofilm formation at the host interface. This work reveals a novel in vivo biofilm regulator that influences the transition of bacteria from their planktonic state in seawater to tight aggregates of cells in the host. The study enriches our understanding of biofilm regulation and beneficial colonization by an animal's microbiome.
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Prada-Ramírez HA, Pérez-Mendoza D, Felipe A, Martínez-Granero F, Rivilla R, Sanjuán J, Gallegos MT. AmrZ regulates cellulose production in Pseudomonas syringae pv. tomato DC3000. Mol Microbiol 2015; 99:960-77. [PMID: 26564578 DOI: 10.1111/mmi.13278] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2015] [Indexed: 11/27/2022]
Abstract
In Pseudomonas syringae pv. tomato DC3000, the second messenger c-di-GMP has been previously shown to stimulate pellicle formation and cellulose biosynthesis. A screen for genes involved in cellulose production under high c-di-GMP intracellular levels led to the identification of insertions in two genes, wssB and wssE, belonging to the Pto DC3000 cellulose biosynthesis operon wssABCDEFGHI. Interestingly, beside cellulose-deficient mutants, colonies with a rougher appearance than the wild type also arouse among the transposants. Those mutants carry insertions in amrZ, a gene encoding a transcriptional regulator in different Pseudomonas. Here, we provide evidence that AmrZ is involved in the regulation of bacterial cellulose production at transcriptional level by binding to the promoter region of the wssABCDEFGHI operon and repressing cellulose biosynthesis genes. Mutation of amrZ promotes wrinkly colony morphology, increased cellulose production and loss of motility in Pto DC3000. AmrZ regulon includes putative c-di-GMP metabolising proteins, like AdcA and MorA, which may also impact those phenotypes. Furthermore, an amrZ but not a cellulose-deficient mutant turned out to be impaired in pathogenesis, indicating that AmrZ is a key regulator of Pto DC3000 virulence probably by controlling bacterial processes other than cellulose production.
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Affiliation(s)
- Harold A Prada-Ramírez
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | - Daniel Pérez-Mendoza
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | - Antonia Felipe
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | | | - Rafael Rivilla
- Department of Biology, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Juan Sanjuán
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | - María-Trinidad Gallegos
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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Augimeri RV, Varley AJ, Strap JL. Establishing a Role for Bacterial Cellulose in Environmental Interactions: Lessons Learned from Diverse Biofilm-Producing Proteobacteria. Front Microbiol 2015; 6:1282. [PMID: 26635751 PMCID: PMC4646962 DOI: 10.3389/fmicb.2015.01282] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 10/31/2015] [Indexed: 01/21/2023] Open
Abstract
Bacterial cellulose (BC) serves as a molecular glue to facilitate intra- and inter-domain interactions in nature. Biosynthesis of BC-containing biofilms occurs in a variety of Proteobacteria that inhabit diverse ecological niches. The enzymatic and regulatory systems responsible for the polymerization, exportation, and regulation of BC are equally as diverse. Though the magnitude and environmental consequences of BC production are species-specific, the common role of BC-containing biofilms is to establish close contact with a preferred host to facilitate efficient host-bacteria interactions. Universally, BC aids in attachment, adherence, and subsequent colonization of a substrate. Bi-directional interactions influence host physiology, bacterial physiology, and regulation of BC biosynthesis, primarily through modulation of intracellular bis-(3'→5')-cyclic diguanylate (c-di-GMP) levels. Depending on the circumstance, BC producers exhibit a pathogenic or symbiotic relationship with plant, animal, or fungal hosts. Rhizobiaceae species colonize plant roots, Pseudomonadaceae inhabit the phyllosphere, Acetobacteriaceae associate with sugar-loving insects and inhabit the carposphere, Enterobacteriaceae use fresh produce as vehicles to infect animal hosts, and Vibrionaceae, particularly Aliivibrio fischeri, colonize the light organ of squid. This review will highlight the diversity of the biosynthesis and regulation of BC in nature by discussing various examples of Proteobacteria that use BC-containing biofilms to facilitate host-bacteria interactions. Through discussion of current data we will establish new directions for the elucidation of BC biosynthesis, its regulation and its ecophysiological roles.
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Affiliation(s)
| | | | - Janice L. Strap
- Molecular Microbial Biochemistry Laboratory, Faculty of Science, University of Ontario Institute of TechnologyOshawa, ON, Canada
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Liang ZX. The expanding roles of c-di-GMP in the biosynthesis of exopolysaccharides and secondary metabolites. Nat Prod Rep 2015; 32:663-83. [PMID: 25666534 DOI: 10.1039/c4np00086b] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The cyclic dinucleotide c-di-GMP has emerged in the last decade as a prevalent intracellular messenger that orchestrates the transition between the motile and sessile lifestyles of many bacterial species. The motile-to-sessile transition is often associated with the formation of extracellular matrix-encased biofilm, an organized community of bacterial cells that often contributes to antibiotic resistance and host-pathogen interaction. It is increasingly clear that c-di-GMP controls motility, biofilm formation and bacterial pathogenicity partially through regulating the production of exopolysaccharides (EPS) and small-molecule secondary metabolites. This review summarizes our current understanding of the regulation of EPS biosynthesis by c-di-GMP in a diversity of bacterial species and highlights the emerging role of c-di-GMP in the biosynthesis of small-molecule secondary metabolites.
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Affiliation(s)
- Zhao-Xun Liang
- Division of Structural Biology & Biochemistry, School of Biological Sciences, Nanyang Technological University, Singapore 637551.
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Römling U, Galperin MY. Bacterial cellulose biosynthesis: diversity of operons, subunits, products, and functions. Trends Microbiol 2015; 23:545-57. [PMID: 26077867 DOI: 10.1016/j.tim.2015.05.005] [Citation(s) in RCA: 310] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/05/2015] [Accepted: 05/18/2015] [Indexed: 12/30/2022]
Abstract
Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits - which differ among various taxa - affect the enzymatic activity and product yield in vivo by modulating (i) the expression of the biosynthesis apparatus, (ii) the export of the nascent β-D-glucan polymer to the cell surface, and (iii) the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of resulting biofilms, which is particularly important for the interactions of bacteria with higher organisms - leading to rhizosphere colonization and modulating the virulence of cellulose-producing bacterial pathogens inside and outside of host cells. We review the organization of four principal types of cellulose synthase operon found in various bacterial genomes, identify additional bcs genes that encode components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms and in the choice between acute infection and persistence in the host.
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Affiliation(s)
- Ute Römling
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
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40
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Salmonella promotes virulence by repressing cellulose production. Proc Natl Acad Sci U S A 2015; 112:5183-8. [PMID: 25848006 DOI: 10.1073/pnas.1500989112] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cellulose is the most abundant organic polymer on Earth. In bacteria, cellulose confers protection against environmental insults and is a constituent of biofilms typically formed on abiotic surfaces. We report that, surprisingly, Salmonella enterica serovar Typhimurium makes cellulose when inside macrophages. We determine that preventing cellulose synthesis increases virulence, whereas stimulation of cellulose synthesis inside macrophages decreases virulence. An attenuated mutant lacking the mgtC gene exhibited increased cellulose levels due to increased expression of the cellulose synthase gene bcsA and of cyclic diguanylate, the allosteric activator of the BcsA protein. Inactivation of bcsA restored wild-type virulence to the Salmonella mgtC mutant, but not to other attenuated mutants displaying a wild-type phenotype regarding cellulose. Our findings indicate that a virulence determinant can promote pathogenicity by repressing a pathogen's antivirulence trait. Moreover, they suggest that controlling antivirulence traits increases long-term pathogen fitness by mediating a trade-off between acute virulence and transmission.
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Cyclic di-GMP: the first 25 years of a universal bacterial second messenger. Microbiol Mol Biol Rev 2013; 77:1-52. [PMID: 23471616 DOI: 10.1128/mmbr.00043-12] [Citation(s) in RCA: 1204] [Impact Index Per Article: 109.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Twenty-five years have passed since the discovery of cyclic dimeric (3'→5') GMP (cyclic di-GMP or c-di-GMP). From the relative obscurity of an allosteric activator of a bacterial cellulose synthase, c-di-GMP has emerged as one of the most common and important bacterial second messengers. Cyclic di-GMP has been shown to regulate biofilm formation, motility, virulence, the cell cycle, differentiation, and other processes. Most c-di-GMP-dependent signaling pathways control the ability of bacteria to interact with abiotic surfaces or with other bacterial and eukaryotic cells. Cyclic di-GMP plays key roles in lifestyle changes of many bacteria, including transition from the motile to the sessile state, which aids in the establishment of multicellular biofilm communities, and from the virulent state in acute infections to the less virulent but more resilient state characteristic of chronic infectious diseases. From a practical standpoint, modulating c-di-GMP signaling pathways in bacteria could represent a new way of controlling formation and dispersal of biofilms in medical and industrial settings. Cyclic di-GMP participates in interkingdom signaling. It is recognized by mammalian immune systems as a uniquely bacterial molecule and therefore is considered a promising vaccine adjuvant. The purpose of this review is not to overview the whole body of data in the burgeoning field of c-di-GMP-dependent signaling. Instead, we provide a historic perspective on the development of the field, emphasize common trends, and illustrate them with the best available examples. We also identify unresolved questions and highlight new directions in c-di-GMP research that will give us a deeper understanding of this truly universal bacterial second messenger.
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Wang ZC, Huang CJ, Huang YJ, Wu CC, Peng HL. FimK regulation on the expression of type 1 fimbriae in Klebsiella pneumoniae CG43S3. MICROBIOLOGY-SGM 2013; 159:1402-1415. [PMID: 23704787 DOI: 10.1099/mic.0.067793-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Klebsiella pneumoniae CG43, a heavy encapsulated liver abscess isolate, mainly expresses type 3 fimbriae. Type 1 fimbriae expression was only apparent in CG43S3ΔmrkA (the type 3 fimbriae-deficient strain). The expression of type 1 fimbriae in CG43S3ΔmrkA was reduced by deleting the fimK gene, but was unaffected by removing the 3' end of fimK encoding the C-terminal EIL domain (EILfimK). Quantitative RT-PCR and promoter activity analysis showed that the putative DNA-binding region at the N terminus, but not the C-terminal EIL domain, of FimK positively affects transcription of the type 1 fimbrial major subunit, fimA. An electrophoretic mobility shift assay demonstrated that the recombinant FimK could specifically bind to fimS, which is located upstream of fimA and contains a vegetative promoter for the fim operon, also reflecting possible transcriptional regulation. EILfimK was shown to encode a functional phosphodiesterase (PDE) via enhancing motility in Escherichia coli JM109 and in vitro using PDE activity assays. Moreover, EILfimK exhibited higher PDE activity than FimK, implying that the N-terminal DNA-binding domain may negatively affect the PDE activity of FimK. FimA expression was detected in CG43S3 expressing EILfimK or AILfimK, suggesting that FimA expression is not directly influenced by the c-di-GMP level. In summary, FimK influences type 1 fimbriation by binding to fimS at the N-terminal domain, and thereafter, the altered protein structure may activate C-terminal PDE activity to reduce the intracellular c-di-GMP level.
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Affiliation(s)
- Zhe-Chong Wang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China
| | - Ching-Jou Huang
- Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China
| | - Ying-Jung Huang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China
| | - Chien-Chen Wu
- Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China
| | - Hwei-Ling Peng
- Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China.,Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China
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Exoprotein production correlates with morphotype changes of nonmotile Shewanella oneidensis mutants. J Bacteriol 2013; 195:1463-74. [PMID: 23335418 DOI: 10.1128/jb.02187-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We report a previously undescribed mechanism for the rugose morphotype in Shewanella oneidensis, a research model for investigating redox transformations of environmental contaminants. Bacteria may form smooth or rugose colonies on agar plates. In general, conversion from the smooth to rugose colony morphotype is attributed to increased production of exopolysaccharide (EPS). In this work, we discovered that aflagellate S. oneidensis mutants grew into rugose colonies, whereas those with nonfunctional flagellar filaments remained smooth. EPS production was not altered in either case, but mutants with the rugose morphotype showed significantly reduced exoprotein secretion. The idea that exoproteins at a reduced level correlate with rugosity gained support from smooth suppressor strains of an aflagellate rugose fliD (encoding the capping protein) mutant, which restored the exoprotein level to the levels of the wild-type and mutant strains with a smooth morphotype. Further analyses revealed that SO1072 (a putative GlcNAc-binding protein) was one of the highly upregulated exoproteins in these suppressor strains. Most intriguingly, this study identified a compensatory mechanism of SO1072 to flagellins possibly mediated by bis-(3'-5')-cyclic dimeric GMP.
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Abstract
Biofilms are multicellular communities of bacteria attached to a surface and embedded in a protective matrix. In many cases, the signals that induce biofilm formation are unknown. Here, we report that biofilm formation by the marine bacterium Vibrio fischeri can be induced by the addition of arabinose to LBS (Luria-Bertani-salt), a tryptone-based medium. Growth of cells in the presence of 0.2% arabinose, but not other sugars, induced the production of a pellicle at the air/liquid interfaces of static cultures. V. fischeri failed to grow on arabinose as the sole carbon source, suggesting that pellicle production did not occur as a result of increased growth, but experiments using the acid/base indicator phenol red suggested that V. fischeri may partially metabolize arabinose. Pellicle production was independent of the syp polysaccharide locus but was altered upon disruption of the bcs cellulose locus. Through a screen for mutants defective for pellicle production, we found that loss of motility disrupted the formation of the arabinose-induced pellicle. Among the ∼20 mutants that retained motility were strains with insertions in a putative msh pilus locus and a strain with a defect in yidK, which is involved in galactose catabolism. Mutants with the msh gene disrupted grew poorly in the presence of arabinose, while the yidK mutant appeared to be "blind" to the presence of arabinose. Finally, arabinose impaired symbiotic colonization by V. fischeri. This work thus identifies a novel signal and new pathways involved in control of biofilm formation by V. fischeri.
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45
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Wang L, Ling Y, Jiang H, Qiu Y, Qiu J, Chen H, Yang R, Zhou D. AphA is required for biofilm formation, motility, and virulence in pandemic Vibrio parahaemolyticus. Int J Food Microbiol 2012; 160:245-51. [PMID: 23290231 DOI: 10.1016/j.ijfoodmicro.2012.11.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 11/03/2012] [Accepted: 11/05/2012] [Indexed: 11/18/2022]
Abstract
AphA is a small PadR-family DNA-binding regulator in vibrios. AphA has been shown to be involved in transcriptional auto-repression, intestinal colonization and lethality in mice, biofilm formation, and quorum sensing in Vibrio cholerae. The AphA protein of Vibrio parahaemolyticus has 85% identity to that of V. cholerae with the same number of amino acids. In this work, the aphA null mutant was constructed from a wild-type pandemic strain of V. parahaemolyticus for characterization of the phenotypic changes. AphA is required for biofilm formation in V. parahaemolyticus, and a decreased production of biofilm exopolysaccharide matrix in the aphA mutant relative to the wild-type parent strain accounts for its reduced biofilm formation. AphA is also necessary for the optimal swimming and swarming motility of V. parahaemolyticus. In addition, AphA is essential for lethality in mice and cytotoxic activity, but the aphA deletion did not have effect on enterotoxicity.
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Affiliation(s)
- Li Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, China
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46
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Whitney JC, Howell PL. Synthase-dependent exopolysaccharide secretion in Gram-negative bacteria. Trends Microbiol 2012; 21:63-72. [PMID: 23117123 DOI: 10.1016/j.tim.2012.10.001] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 09/28/2012] [Accepted: 10/03/2012] [Indexed: 01/26/2023]
Abstract
The biosynthesis and export of bacterial cell-surface polysaccharides is known to occur through several distinct mechanisms. Recent advances in the biochemistry and structural biology of several proteins in synthase-dependent polysaccharide secretion systems have identified key conserved components of this pathway in Gram-negative bacteria. These components include an inner-membrane-embedded polysaccharide synthase, a periplasmic tetratricopeptide repeat (TPR)-containing scaffold protein, and an outer-membrane β-barrel porin. There is also increasing evidence that many synthase-dependent systems are post-translationally regulated by the bacterial second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). Here, we compare these core proteins in the context of the alginate, cellulose, and poly-β-D-N-acetylglucosamine (PNAG) secretion systems.
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Affiliation(s)
- J C Whitney
- Program in Molecular Structure and Function, The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
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Tagliabue L, Maciąg A, Antoniani D, Landini P. TheyddV-dosoperon controls biofilm formation through the regulation of genes encoding curli fibers' subunits in aerobically growingEscherichia coli. ACTA ACUST UNITED AC 2010; 59:477-84. [DOI: 10.1111/j.1574-695x.2010.00702.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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48
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Identification and characterization of a phosphodiesterase that inversely regulates motility and biofilm formation in Vibrio cholerae. J Bacteriol 2010; 192:4541-52. [PMID: 20622061 DOI: 10.1128/jb.00209-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae switches between free-living motile and surface-attached sessile lifestyles. Cyclic diguanylate (c-di-GMP) is a signaling molecule controlling such lifestyle changes. C-di-GMP is synthesized by diguanylate cyclases (DGCs) that contain a GGDEF domain and is degraded by phosphodiesterases (PDEs) that contain an EAL or HD-GYP domain. We constructed in-frame deletions of all V. cholerae genes encoding proteins with GGDEF and/or EAL domains and screened mutants for altered motility phenotypes. Of 52 mutants tested, four mutants exhibited an increase in motility, while three mutants exhibited a decrease in motility. We further characterized one mutant lacking VC0137 (cdgJ), which encodes an EAL domain protein. Cellular c-di-GMP quantifications and in vitro enzymatic activity assays revealed that CdgJ functions as a PDE. The cdgJ mutant had reduced motility and exhibited a small decrease in flaA expression; however, it was able to produce a flagellum. This mutant had enhanced biofilm formation and vps gene expression compared to that of the wild type, indicating that CdgJ inversely regulates motility and biofilm formation. Genetic interaction analysis revealed that at least four DGCs, together with CdgJ, control motility in V. cholerae.
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