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Chen T, Zhou X, Feng R, Shi S, Chen X, Wei B, Hu Z, Peng T. Novel function of single-target regulator NorR involved in swarming motility and biofilm formation revealed in Vibrio alginolyticus. BMC Biol 2024; 22:253. [PMID: 39506750 PMCID: PMC11542441 DOI: 10.1186/s12915-024-02057-y] [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: 01/11/2024] [Accepted: 10/30/2024] [Indexed: 11/08/2024] Open
Abstract
NorR, as a single-target regulator, has been demonstrated to be involved in NO detoxification in bacteria under anaerobic conditions. Here, the norR gene was identified and deleted in the genome of Vibrio alginolyticus. The results showed that deletion of norR in Vibrio alginolyticus led to lower swarming motility and more biofilm formation on aerobic condition. Moreover, we proved that NorR from E. coli had a similar function in controlling motility. NorR overexpression led to increased resistance to oxidative stress and tetracycline. We also observed a reduced ability of the NorR-overexpressing strain to adapt to iron limitation condition. Transcriptome analysis showed that the genes responsible for bacterial motility and biofilm formation were affected by NorR. The expressions of several sigma factors (RpoS, RpoN, and RpoH) and response regulators (LuxR and MarR) were also controlled by NorR. Furthermore, Chip-qPCR showed that there is a direct binding between NorR and the promoter of rpoS. Based on these results, NorR appears to be a central regulator involved in biofilm formation and swarming motility in Vibrio alginolyticus.
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Affiliation(s)
- Tongxian Chen
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
- Dongguan Nancheng Business District North School, Dongguan, 523000, China
| | - Xiaoling Zhou
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
| | - Ruonan Feng
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
| | - Shuhao Shi
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
| | - Xiyu Chen
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
| | - Bingqi Wei
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
| | - Zhong Hu
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China
| | - Tao Peng
- School of Resources and Environmental Engineering, Jiangsu University of Technology, 1801 Zhongwu Avenue, Changzhou, 213001, China.
- Department of Biology, Shantou University, Shantou, Guangdong, 515063, China.
- Dongguan Nancheng Business District North School, Dongguan, 523000, China.
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Septer AN, Visick KL. Lighting the way: how the Vibrio fischeri model microbe reveals the complexity of Earth's "simplest" life forms. J Bacteriol 2024; 206:e0003524. [PMID: 38695522 PMCID: PMC11112999 DOI: 10.1128/jb.00035-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024] Open
Abstract
Vibrio (Aliivibrio) fischeri's initial rise to fame derived from its alluring production of blue-green light. Subsequent studies to probe the mechanisms underlying this bioluminescence helped the field discover the phenomenon now known as quorum sensing. Orthologs of quorum-sensing regulators (i.e., LuxR and LuxI) originally identified in V. fischeri were subsequently uncovered in a plethora of bacterial species, and analogous pathways were found in yet others. Over the past three decades, the study of this microbe has greatly expanded to probe the unique role of V. fischeri as the exclusive symbiont of the light organ of the Hawaiian bobtail squid, Euprymna scolopes. Buoyed by this optically amenable host and by persistent and insightful researchers who have applied novel and cross-disciplinary approaches, V. fischeri has developed into a robust model for microbe-host associations. It has contributed to our understanding of how bacteria experience and respond to specific, often fluxing environmental conditions and the mechanisms by which bacteria impact the development of their host. It has also deepened our understanding of numerous microbial processes such as motility and chemotaxis, biofilm formation and dispersal, and bacterial competition, and of the relevance of specific bacterial genes in the context of colonizing an animal host. Parallels in these processes between this symbiont and bacteria studied as pathogens are readily apparent, demonstrating functional conservation across diverse associations and permitting a reinterpretation of "pathogenesis." Collectively, these advances built a foundation for microbiome studies and have positioned V. fischeri to continue to expand the frontiers of our understanding of the microbial world inside animals.
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Affiliation(s)
- Alecia N. Septer
- Department of Earth, Marine and Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Karen L. Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
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Sanchez S, Ng WL. Motility Control as a Possible Link Between Quorum Sensing to Surface Attachment in Vibrio Species. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1404:65-75. [PMID: 36792871 DOI: 10.1007/978-3-031-22997-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
In this chapter, we discuss motility control as a possible link between quorum sensing (QS) to surface attachment in Vibrio species. QS regulates a variety of behaviors that are important for the life cycle of many bacterial species, including virulence factor production, biofilm formation, or metabolic homeostasis. Therefore, without QS, many species of bacteria cannot survive in their natural environments. Here, we summarize several QS systems in different Vibrio species and discuss some of emerging features that suggest QS is intimately connected to motility control. Finally, we speculate the connection between motility and QS is critical for Vibrio species to detect solid surfaces for surface attachment.
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Affiliation(s)
- Sandra Sanchez
- Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, MA, USA
| | - Wai-Leung Ng
- Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, MA, USA.
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Giovanni A, Maekawa S, Wang PC, Chen SC. Recombinant Vibrio harveyi flagellin A protein and partial deletions of middle variable region and D0 domain induce immune related genes in Epinephelus coioides and Cyprinus carpio. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 139:104588. [PMID: 36372114 DOI: 10.1016/j.dci.2022.104588] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 11/04/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Vibrio harveyi is a Gram-negative bacterium that causes vibriosis in various aquaculture species, including the orange-spotted grouper (Epinephelus coioides). Bacterial flagellin is a potent pathogen-associated molecule that stimulates the innate and adaptive immune systems through toll-like receptor 5 (TLR5) signaling. In this study, we isolated V. harveyi flagellin A (VhFliA) gene from V. harveyi (originated from orange-spotted grouper) and investigated the in vivo activities of recombinant VhFliA protein. Multiple sequence alignment showed that the amino acid sequence of VhFliA has conserved domains of N- and C-terminals (D0 and D1) and a middle variable (MV) region. We produced the VhFliA recombinant protein (wild type (WT)-VhFliA) by Escherichia coli and investigated its in vivo biological activity. Additionally, we prepared the VhFliA recombinant proteins with deletion of domains (ΔMV-VhFliA and ΔD0MV-VhFliA) to identify the domain for biological activity in the orange-spotted grouper. WT and ΔMV-VhFliA induced the expression of inflammatory cytokines (IFNγ, IL-1β, and IL-8) in groupers. However, ΔD0MV-VhFliA did not induce the expression of inflammatory cytokines. Additionally, to demonstrate the applicability of recombinant VhFliA to teleost species, we performed an in vivo assay of the recombinant proteins in koi carp (Cyprinus carpio). WT-VhFliA stimulates the expression of inflammatory cytokines (IL-1β, IL-6, and IL-8) in carp. ΔMV-VhFliA did not upregulate IL-1β and IL-6, whereas ΔD0MV-VhFliA induced expression in carp. These findings showed the potential of VhFliA as an effective immune stimulant adjuvant and comparative studies of flagellin - TLR5 signaling in teleosts.
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Affiliation(s)
- Andre Giovanni
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shun Maekawa
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan; Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan; General Research Service Centre, National Pingtung University of Science and Technology, Pingtung, Taiwan.
| | - Pei-Chi Wang
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan; Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shih-Chu Chen
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan; Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan.
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Zhang W, Chen L, Feng H, Wang J, Zeng F, Xiao X, Jian J, Wang N, Pang H. Functional characterization of Vibrio alginolyticus T3SS regulator ExsA and evaluation of its mutant as a live attenuated vaccine candidate in zebrafish ( Danio rerio) model. Front Vet Sci 2022; 9:938822. [PMID: 37265802 PMCID: PMC10230115 DOI: 10.3389/fvets.2022.938822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 07/14/2022] [Indexed: 06/03/2023] Open
Abstract
Vibrio alginolyticus, a Gram-negative bacterium, is an opportunistic pathogen of both marine animals and humans, resulting in significant losses in the aquaculture industry. Type III secretion system (T3SS) is a crucial virulence mechanism of V. alginolyticus. In this study, the T3SS regulatory gene exsA, which was cloned from V. alginolyticus wild-type strain HY9901, is 861 bp encoding a protein of 286 amino acids. The ΔexsA was constructed by homologous recombination and Overlap-PCR. Although there was no difference in growth between HY9901 and ΔexsA, the ΔexsA exhibited significantly decreased extracellular protease activity and biofilm formation. Besides, the ΔexsA showed a weakened swarming phenotype and an ~100-fold decrease in virulence to zebrafish. Antibiotic susceptibility testing showed the HY9901ΔexsA was more sensitive to kanamycin, minocycline, tetracycline, gentamicin, doxycycline and neomycin. Compared to HY9901 there were 541 up-regulated genes and 663 down-regulated genes in ΔexsA, screened by transcriptome sequencing. qRT-PCR and β-galactosidase reporter assays were used to analyze the transcription levels of hop gene revealing that exsA gene could facilitate the expression of hop gene. Finally, Danio rerio, vaccinated with ΔexsA through intramuscular injection, induced a relative percent survival (RPS) value of 66.7% after challenging with HY9901 wild type strain. qRT-PCR assays showed that vaccination with ΔexsA increased the expression of immune-related genes, including GATA-1, IL6, IgM, and TNF-α in zebrafish. In summary, these results demonstrate the importance of exsA in V. alginolyticus and provide a basis for further investigations into the virulence and infection mechanism.
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Affiliation(s)
- Weijie Zhang
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Liangchuan Chen
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Haiyun Feng
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Junlin Wang
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Fuyuan Zeng
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Xing Xiao
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Jichang Jian
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Na Wang
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Huanying Pang
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
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6
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Lynch JB, James N, McFall-Ngai M, Ruby EG, Shin S, Takagi D. Transitioning to confined spaces impacts bacterial swimming and escape response. Biophys J 2022; 121:2653-2662. [PMID: 35398019 PMCID: PMC9300662 DOI: 10.1016/j.bpj.2022.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/28/2021] [Accepted: 04/05/2022] [Indexed: 11/02/2022] Open
Abstract
Symbiotic bacteria often navigate complex environments before colonizing privileged sites in their host organism. Chemical gradients are known to facilitate directional taxis of these bacteria, guiding them toward their eventual destination. However, less is known about the role of physical features in shaping the path the bacteria take and defining how they traverse a given space. The flagellated marine bacterium Vibrio fischeri, which forms a binary symbiosis with the Hawaiian bobtail squid, Euprymna scolopes, must navigate tight physical confinement during colonization, squeezing through a tissue bottleneck constricting to ∼2 μm in width on the way to its eventual home. Using microfluidic in vitro experiments, we discovered that V. fischeri cells alter their behavior upon entry into confined space, straightening their swimming paths and promoting escape from confinement. Using a computational model, we attributed this escape response to two factors: reduced directional fluctuation and a refractory period between reversals. Additional experiments in asymmetric capillary tubes confirmed that V. fischeri quickly escape from confined ends, even when drawn into the ends by chemoattraction. This avoidance was apparent down to a limit of confinement approaching the diameter of the cell itself, resulting in a balance between chemoattraction and evasion of physical confinement. Our findings demonstrate that nontrivial distributions of swimming bacteria can emerge from simple physical gradients in the level of confinement. Tight spaces may serve as an additional, crucial cue for bacteria while they navigate complex environments to enter specific habitats.
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Affiliation(s)
- Jonathan B Lynch
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawai'i.
| | - Nicholas James
- Department of Cell and Molecular Biology, University of Hawai'i at Mānoa, Honolulu, Hawai'i
| | - Margaret McFall-Ngai
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawai'i
| | - Edward G Ruby
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawai'i
| | - Sangwoo Shin
- Department of Mechanical Engineering, University of Hawai'i at Mānoa, Honolulu, Hawai'i; Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, New York
| | - Daisuke Takagi
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawai'i; Department of Mechanical Engineering, University of Hawai'i at Mānoa, Honolulu, Hawai'i; Department of Mathematics, University of Hawai'i at Mānoa, Honolulu, Hawai'i
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7
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Tan H, Da F, Lin G, Wan X, Cai S, Cai J, Qin Q. Construction of a phosphodiesterase mutant and evaluation of its potential as an effective live attenuated vaccine in pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus). FISH & SHELLFISH IMMUNOLOGY 2022; 124:543-551. [PMID: 35460878 DOI: 10.1016/j.fsi.2022.04.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/11/2022] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
Vibrio alginolyticus is a dominant pathogen that causes vibriosis of fish and shellfish. VAGM003125 is a specific phosphodiesterase bearing HD-GYP domain, which extensively regulates multicellular behavior and physiological processes in bacteria. In this study, an in-frame deleted ΔVAGM003125 mutant was constructed and changes of ΔVAGM003125 mutant in physiology and pathogenicity were examined. The potential application of ΔVAGM003125 mutant as a live attenuated vaccine was also assessed. The ΔVAGM003125 mutant displayed no significant differences in the growth rate and morphology in comparison to the wild type strain. However, the ΔVAGM003125 mutant significantly enhanced biofilm formation compared to the wild type strain. Also, the ΔVAGM003125 mutant was noted as being able to attenuate swarming motility, ECPase, and adherence compared to the wild type strain. Moreover, the ΔVAGM003125 mutant induced high antibody titers and provided effective immune protection, which was evidenced with a relative survival rate of 81% without histopathological abnormality. Following ΔVAGM003125 mutant vaccination, immune-related genes of pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus) including IgM, MHC-Iα, IL-16, IL-1, and TNF-α was up-regulated. Taken together, the present data suggested that the ΔVAGM003125 mutant might be applied as an attenuated live vaccination against V. alginolyticus during fish culture.
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Affiliation(s)
- Huiming Tan
- Fisheries College of Guangdong Ocean University, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Fan Da
- Fisheries College of Guangdong Ocean University, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Guixiang Lin
- Fisheries College of Guangdong Ocean University, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Xiaoju Wan
- Fisheries College of Guangdong Ocean University, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China
| | - Shuanghu Cai
- Fisheries College of Guangdong Ocean University, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China; Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen Institute of Guangdong Ocean University, Shenzhen, China.
| | - Jia Cai
- Fisheries College of Guangdong Ocean University, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Zhanjiang, China; Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen Institute of Guangdong Ocean University, Shenzhen, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangzhou, China
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8
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The polar flagellar transcriptional regulatory network in Vibrio campbellii deviates from canonical Vibrio species. J Bacteriol 2021; 203:e0027621. [PMID: 34339299 DOI: 10.1128/jb.00276-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Swimming motility is a critical virulence factor in pathogenesis for numerous Vibrio species. Vibrio campbellii DS40M4 is a wild isolate that has been recently established as a highly tractable model strain for bacterial genetics studies. We sought to exploit the tractability and relevance of this strain for characterization of flagellar gene regulation in V. campbellii. Using comparative genomics, we identified homologs of V. campbellii flagellar and chemotaxis genes conserved in other members of the Vibrionaceae and determined the transcriptional profile of these loci using differential RNA-seq. We systematically deleted all 63 predicted flagellar and chemotaxis genes in V. campbellii and examined their effects on motility and flagellum production. We specifically focused on the core regulators of the flagellar hierarchy established in other vibrios: RpoN (σ54), FlrA, FlrC, and FliA. Our results show that V. campbellii transcription of flagellar and chemotaxis genes is governed by a multi-tiered regulatory hierarchy similar to other motile Vibrio species. However, there are several critical differences in V. campbellii: (i) the σ54-dependent regulator FlrA is dispensable for motility, (ii) the flgA, fliEFGHIJ, flrA, and flrBC operons do not require σ54 for expression, and (iii) FlrA and FlrC co-regulate class II genes. Our model proposes that the V. campbellii flagellar transcriptional hierarchy has three classes of genes, in contrast to the four-class hierarchy in Vibrio cholerae. Our genetic and phenotypic dissection of the V. campbellii flagellar regulatory network highlights the differences that have evolved in flagellar regulation across the Vibrionaceae. Importance Vibrio campbellii is a Gram-negative bacterium that is free-living and ubiquitous in marine environments and is an important global pathogen of fish and shellfish. Disruption of the flagellar motor significantly decreases host mortality of V. campbellii, suggesting that motility is a key factor in pathogenesis. Using this model organism, we identified >60 genes that encode proteins with predicted structural, mechanical, or regulatory roles in function of the single polar flagellum in V. campbellii. We systematically tested strains containing single deletions of each gene to determine the impact on motility and flagellum production. Our studies have uncovered differences in the regulatory network and function of several genes in V. campbellii as compared to established systems in Vibrio cholerae and Vibrio parahaemolyticus.
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9
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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: 64] [Impact Index Per Article: 16.0] [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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10
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Grognot M, Taute KM. More than propellers: how flagella shape bacterial motility behaviors. Curr Opin Microbiol 2021; 61:73-81. [PMID: 33845324 DOI: 10.1016/j.mib.2021.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/05/2021] [Accepted: 02/14/2021] [Indexed: 12/22/2022]
Abstract
Bacteria use a wide variety of flagellar architectures to navigate their environment. While the iconic run-tumble motility strategy of the peritrichously flagellated Escherichia coli has been well studied, recent work has revealed a variety of new motility behaviors that can be achieved with different flagellar architectures, such as single, bundled, or opposing polar flagella. The recent discovery of various flagellar gymnastics such as flicking and flagellar wrapping is increasingly shifting the view from flagella as passive propellers to versatile appendages that can be used in a wide range of conformations. Here, we review recent observations of how flagella shape motility behaviors and summarize the nascent structure-function map linking flagellation and behavior.
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Affiliation(s)
- Marianne Grognot
- Rowland Institute at Harvard, 100 Edwin H Land Blvd, Cambridge, MA 02142, USA
| | - Katja M Taute
- Rowland Institute at Harvard, 100 Edwin H Land Blvd, Cambridge, MA 02142, USA.
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11
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Vroom MM, Rodriguez-Ocasio Y, Lynch JB, Ruby EG, Foster JS. Modeled microgravity alters lipopolysaccharide and outer membrane vesicle production of the beneficial symbiont Vibrio fischeri. NPJ Microgravity 2021; 7:8. [PMID: 33686090 PMCID: PMC7940393 DOI: 10.1038/s41526-021-00138-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/02/2021] [Indexed: 01/04/2023] Open
Abstract
Reduced gravity, or microgravity, can have a pronounced impact on the physiology of animals, but the effects on their associated microbiomes are not well understood. Here, the impact of modeled microgravity on the shedding of Gram-negative lipopolysaccharides (LPS) by the symbiotic bacterium Vibrio fischeri was examined using high-aspect ratio vessels. LPS from V. fischeri is known to induce developmental apoptosis within its symbiotic tissues, which is accelerated under modeled microgravity conditions. In this study, we provide evidence that exposure to modeled microgravity increases the amount of LPS released by the bacterial symbiont in vitro. The higher rates of shedding under modeled microgravity conditions are associated with increased production of outer-membrane vesicles (OMV), which has been previously correlated to flagellar motility. Mutants of V. fischeri defective in the production and rotation of their flagella show significant decreases in LPS shedding in all treatments, but levels of LPS are higher under modeled microgravity despite loss of motility. Modeled microgravity also appears to affect the outer-membrane integrity of V. fischeri, as cells incubated under modeled microgravity conditions are more susceptible to cell-membrane-disrupting agents. These results suggest that, like their animal hosts, the physiology of symbiotic microbes can be altered under microgravity-like conditions, which may have important implications for host health during spaceflight.
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Affiliation(s)
- Madeline M Vroom
- Department of Microbiology and Cell Science, Space Life Science Lab, University of Florida, Merritt Island, FL, USA
| | - Yaneli Rodriguez-Ocasio
- Department of Microbiology and Cell Science, Space Life Science Lab, University of Florida, Merritt Island, FL, USA
| | - Jonathan B Lynch
- Pacific Biosciences Research Center, Kewalo Marine Laboratory, University of Hawai'i at Manoa, Honolulu, HI, USA.,Department of Integrative Biology and Physiology, University of California, Los Angeles, CA, USA
| | - Edward G Ruby
- Pacific Biosciences Research Center, Kewalo Marine Laboratory, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Jamie S Foster
- Department of Microbiology and Cell Science, Space Life Science Lab, University of Florida, Merritt Island, FL, USA.
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Avila-Calderón ED, Ruiz-Palma MDS, Aguilera-Arreola MG, Velázquez-Guadarrama N, Ruiz EA, Gomez-Lunar Z, Witonsky S, Contreras-Rodríguez A. Outer Membrane Vesicles of Gram-Negative Bacteria: An Outlook on Biogenesis. Front Microbiol 2021; 12:557902. [PMID: 33746909 PMCID: PMC7969528 DOI: 10.3389/fmicb.2021.557902] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 02/04/2021] [Indexed: 12/14/2022] Open
Abstract
Outer membrane vesicles (OMVs) from Gram-negative bacteria were first described more than 50 years ago. However, the molecular mechanisms involved in biogenesis began to be studied only in the last few decades. Presently, the biogenesis and molecular mechanisms for their release are not completely known. This review covers the most recent information on cellular components involved in OMV biogenesis, such as lipoproteins and outer membrane proteins, lipopolysaccharide, phospholipids, quorum-sensing molecules, and flagella.
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Affiliation(s)
- Eric Daniel Avila-Calderón
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, Mexico.,Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, CINVESTAV-IPN, México City, Mexico
| | - María Del Socorro Ruiz-Palma
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, Mexico.,División Químico Biológicas, Universidad Tecnológica de Tecámac, Tecámac, Mexico
| | - Ma Guadalupe Aguilera-Arreola
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, Mexico
| | - Norma Velázquez-Guadarrama
- Unidad de Investigación en enfermedades infecciosas, Hospital Infantil de México Federico Gómez, Ciudad de México, Mexico
| | - Enrico A Ruiz
- Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, Mexico
| | - Zulema Gomez-Lunar
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, Mexico
| | - Sharon Witonsky
- Center for One Health Research, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.,Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
| | - Araceli Contreras-Rodríguez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, Mexico
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Eguchi N, Suzuki S, Yokota K, Igimi S, Kajikawa A. Ligilactobacillus agilis BKN88 possesses thermo-/acid-stable heteropolymeric flagellar filaments. MICROBIOLOGY-SGM 2021; 167. [PMID: 33502302 DOI: 10.1099/mic.0.001020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Many flagellated bacteria possess multiple flagellins, but the roles and the compositions of each flagellin are diverse and poorly understood. In Ligilactobacillus agilis BKN88, there are two active flagellin gene paralogues but their function and composition in its flagellar filaments have not been described. The aim of this study is to find the function and composition of the flagellins by employing mutant strains each of which expresses a single flagellin or a modified flagellin. Two single flagellin-expressing strains were both flagellated while the number of flagella per cell in the single flagellin-expressing derivatives was lower than that in the wild type. Nonetheless, these derivative strains were apparently equally motile as the wild type. This indicates that either flagellin is sufficient for cell motility. The immunological activity via Toll-like receptor 5 of the single flagellin-expressing strains or purified single flagellins was readily detectable but mostly variably weaker than that of the wild type. The flagellar filaments of wild type L. agilis BKN88 were more acid-/thermo-stable than those of single flagellin-expressing derivatives. Using a combination of immunoprecipitation and flagellin-specific staining, wild type BKN88 appeared to possess heteropolymeric flagellar filaments consisting of both flagellins and each flagellin appeared to be equally distributed throughout the filaments. The results of this study suggest that the two flagellins together form a more robust filament than either alone and are thus functionally complementary.
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Affiliation(s)
- Naoto Eguchi
- Department of Agricultural Chemistry, Graduate School of Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Shunya Suzuki
- Department of Agricultural Chemistry, Graduate School of Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Kenji Yokota
- Department of Agricultural Chemistry, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Shizunobu Igimi
- Department of Agricultural Chemistry, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Akinobu Kajikawa
- Department of Agricultural Chemistry, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
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14
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Multiplexed Competition in a Synthetic Squid Light Organ Microbiome Using Barcode-Tagged Gene Deletions. mSystems 2020; 5:5/6/e00846-20. [PMID: 33323415 PMCID: PMC7771539 DOI: 10.1128/msystems.00846-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Beneficial microbes play essential roles in the health and development of their hosts. However, the complexity of animal microbiomes and general genetic intractability of their symbionts have made it difficult to study the coevolved mechanisms for establishing and maintaining specificity at the microbe-animal host interface. Beneficial symbioses between microbes and their eukaryotic hosts are ubiquitous and have widespread impacts on host health and development. The binary symbiosis between the bioluminescent bacterium Vibrio fischeri and its squid host Euprymna scolopes serves as a model system to study molecular mechanisms at the microbe-animal interface. To identify colonization factors in this system, our lab previously conducted a global transposon insertion sequencing (INSeq) screen and identified over 300 putative novel squid colonization factors in V. fischeri. To pursue mechanistic studies on these candidate genes, we present an approach to quickly generate barcode-tagged gene deletions and perform high-throughput squid competition experiments with detection of the proportion of each strain in the mixture by barcode sequencing (BarSeq). Our deletion approach improves on previous techniques based on splicing by overlap extension PCR (SOE-PCR) and tfoX-based natural transformation by incorporating a randomized barcode that results in unique DNA sequences within each deletion scar. Amplicon sequencing of the pool of barcoded strains before and after colonization faithfully reports on known colonization factors and provides increased sensitivity over colony counting methods. BarSeq enables rapid and sensitive characterization of the molecular factors involved in establishing the Vibrio-squid symbiosis and provides a valuable tool to interrogate the molecular dialogue at microbe-animal host interfaces. IMPORTANCE Beneficial microbes play essential roles in the health and development of their hosts. However, the complexity of animal microbiomes and general genetic intractability of their symbionts have made it difficult to study the coevolved mechanisms for establishing and maintaining specificity at the microbe-animal host interface. Model symbioses are therefore invaluable for studying the mechanisms of beneficial microbe-host interactions. Here, we present a combined barcode-tagged deletion and BarSeq approach to interrogate the molecular dialogue that ensures specific and reproducible colonization of the Hawaiian bobtail squid by Vibrio fischeri. The ability to precisely manipulate the bacterial genome, combined with multiplex colonization assays, will accelerate the use of this valuable model system for mechanistic studies of how environmental microbes—both beneficial and pathogenic—colonize specific animal hosts.
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15
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Dai F, Li Y, Shao Y, Li C, Zhang W. FliC of Vibrio splendidus-related strain involved in adhesion to Apostichopus japonicus. Microb Pathog 2020; 149:104503. [PMID: 32941968 DOI: 10.1016/j.micpath.2020.104503] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/17/2020] [Accepted: 09/11/2020] [Indexed: 10/23/2022]
Abstract
Vibrio splendidus-related strains are important opportunistic marine pathogens, and they can infect many important marine animals, including the sea cucumber Apostichopus japonicus. In this study, one gene coding flagellin was cloned and a V. splendidus-related strain AJ01/GFPFliC with the overexpression of fliC gene was constructed to explore the function of FliC. AJ01/GFPFliC showed a 3-4 h delay in the initial growth phase and then its growth was faster than that of the wild type strain AJ01. The abilities of swarming motility and biofilm formation ability of AJ01/GFPFliC were also higher than that of AJ01. The adhesion rate of AJ01/GFPFliC to the slide and the coelomocytes of A. japonicus increased from 1% to 5%, and 25% to 40%, respectively, and the adhered AJ01/GFPFliC cells in intestinal tissue of A. japonicus reached 8.0 × 106 CFU/g, which was 2.5-fold higher than that of the control strain AJ01/GFP. Concluded from all the data suggested that FliC was an adhesion factor of V. splendidus-related strain AJ01 that could also contribute to bacterial swarming motility and biofilm formation.
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Affiliation(s)
- Fa Dai
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; School of Marine Sciences, Ningbo University, Ningbo, 315832, PR China
| | - Ya Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; School of Marine Sciences, Ningbo University, Ningbo, 315832, PR China
| | - Yina Shao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; School of Marine Sciences, Ningbo University, Ningbo, 315832, PR China
| | - Chenghua Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; School of Marine Sciences, Ningbo University, Ningbo, 315832, PR China
| | - Weiwei Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; School of Marine Sciences, Ningbo University, Ningbo, 315832, PR China.
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16
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Zhou S, Tu X, Pang H, Hoare R, Monaghan SJ, Luo J, Jian J. A T3SS Regulator Mutant of Vibrio alginolyticus Affects Antibiotic Susceptibilities and Provides Significant Protection to Danio rerio as a Live Attenuated Vaccine. Front Cell Infect Microbiol 2020; 10:183. [PMID: 32411620 PMCID: PMC7198820 DOI: 10.3389/fcimb.2020.00183] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 04/06/2020] [Indexed: 11/13/2022] Open
Abstract
Vibrio alginolyticus is a major cause of Vibriosis in farmed marine aquatic animals and has caused large economic losses to the Asian aquaculture industry in recent years. Therefore, it is necessary to control V. alginolyticus effectively. The virulence mechanism of V. alginolyticus, the Type III secretion system (T3SS), is closely related to its pathogenicity. In this study, the T3SS gene tyeA was cloned from V. alginolyticus wild-type strain HY9901 and the results showed that the deduced amino acid sequence of V. alginolyticus tyeA shared 75–83% homology with other Vibrio spp. The mutant strain HY9901ΔtyeA was constructed by Overlap-PCR and homologous recombination techniques. The HY9901ΔtyeA mutant exhibited an attenuated swarming phenotype and an ~40-fold reduction in virulence to zebrafish. However, the HY9901ΔtyeA mutant showed no difference in growth, biofilm formation and ECPase activity. Antibiotic susceptibility test was observed that wild and mutant strains were extremely susceptible to Amikacin, Minocycline, Gentamicin, Cefperazone; and resistant to oxacillin, clindamycin, ceftazidime. In contrast wild strains are sensitive to tetracycline, chloramphenicol, kanamycin, doxycycline, while mutant strains are resistant to them. qRT-PCR was employed to analyze the transcription levels of T3SS-related genes, the results showed that compared with HY9901 wild type, ΔtyeA had increased expression of vscL, vscK, vscO, vopS, vopN, vscN, and hop. Following vaccination with the mutant strain, zebrafish had significantly higher survival than controls following infection with the wild-type HY9901 (71.2% relative percent survival; RPS). Analysis of immune gene expression by qPCR showed that vaccination with HY9901ΔtyeA increased the expression of IgM, IL-1β, IL-6, and TNF-α in zebrafish. This study provides evidence of protective efficacy of a live attenuated vaccine targeting the T3SS of V. alginolyticus which may be facilitated by up-regulated pro-inflammatory and immunoglobulin-related genes.
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Affiliation(s)
- Shihui Zhou
- Shenzhen Institute of Guangdong Ocean University, Shenzhen, China.,Fisheries College, Guangdong Ocean University, Zhanjiang, China.,Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, China.,Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, China.,Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xueting Tu
- Shenzhen Institute of Guangdong Ocean University, Shenzhen, China.,Fisheries College, Guangdong Ocean University, Zhanjiang, China.,Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, China.,Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, China.,Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Huanying Pang
- Shenzhen Institute of Guangdong Ocean University, Shenzhen, China.,Fisheries College, Guangdong Ocean University, Zhanjiang, China.,Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, China.,Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, China.,Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Rowena Hoare
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Sean J Monaghan
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Jiajun Luo
- Fisheries College, Guangdong Ocean University, Zhanjiang, China.,Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, China.,Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, China
| | - Jichan Jian
- Fisheries College, Guangdong Ocean University, Zhanjiang, China.,Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, China.,Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, China.,Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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17
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Chu J, Liu J, Hoover TR. Phylogenetic Distribution, Ultrastructure, and Function of Bacterial Flagellar Sheaths. Biomolecules 2020; 10:biom10030363. [PMID: 32120823 PMCID: PMC7175336 DOI: 10.3390/biom10030363] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
A number of Gram-negative bacteria have a membrane surrounding their flagella, referred to as the flagellar sheath, which is continuous with the outer membrane. The flagellar sheath was initially described in Vibrio metschnikovii in the early 1950s as an extension of the outer cell wall layer that completely surrounded the flagellar filament. Subsequent studies identified other bacteria that possess flagellar sheaths, most of which are restricted to a few genera of the phylum Proteobacteria. Biochemical analysis of the flagellar sheaths from a few bacterial species revealed the presence of lipopolysaccharide, phospholipids, and outer membrane proteins in the sheath. Some proteins localize preferentially to the flagellar sheath, indicating mechanisms exist for protein partitioning to the sheath. Recent cryo-electron tomography studies have yielded high resolution images of the flagellar sheath and other structures closely associated with the sheath, which has generated insights and new hypotheses for how the flagellar sheath is synthesized. Various functions have been proposed for the flagellar sheath, including preventing disassociation of the flagellin subunits in the presence of gastric acid, avoiding activation of the host innate immune response by flagellin, activating the host immune response, adherence to host cells, and protecting the bacterium from bacteriophages.
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Affiliation(s)
- Joshua Chu
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA;
| | - Jun Liu
- Microbial Sciences Institute, Department of Microbial Pathogenesis, Yale University, West Haven, CT 06516, USA;
| | - Timothy R. Hoover
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
- Correspondence: ; Tel.: +1-706-542-2675
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18
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Abstract
Bacterial and archaeal flagellins are remarkable in having a shared region with variation in housekeeping proteins and a region with extreme diversity, perhaps greater than for any other protein. Analysis of the 113,285 available full-gene sequences of flagellin genes from published bacterial and archaeal sequences revealed the nature and enormous extent of flagellin diversity. There were 35,898 unique amino acid sequences that were resolved into 187 clusters. Analysis of the Escherichia coli and Salmonella enterica flagellins revealed that the variation occurs at two levels. The first is the division of the variable regions into sequence forms that are so divergent that there is no meaningful alignment even within species, and these corresponded to the E. coli or S. enterica H-antigen groups. The second level is variation within these groups, which is extensive in both species. Shared sequence would allow PCR of the variable regions and thus strain-level analysis of microbiome DNA. Flagellin, the agent of prokaryotic flagellar motion, is very widely distributed and is the H antigen of serology. Flagellin molecules have a variable region that confers serotype specificity, encoded by the middle of the gene, and also conserved regions encoded by the two ends of the gene. We collected all available prokaryotic flagellin protein sequences and found the variable region diversity to be at two levels. In each species investigated, there are hypervariable region (HVR) forms without detectable homology in protein sequences between them. There is also considerable variation within HVR forms, indicating that some have been diverging for thousands of years and that interphylum horizontal gene transfers make a major contribution to the evolution of such atypical diversity. IMPORTANCE Bacterial and archaeal flagellins are remarkable in having a shared region with variation in housekeeping proteins and a region with extreme diversity, perhaps greater than for any other protein. Analysis of the 113,285 available full-gene sequences of flagellin genes from published bacterial and archaeal sequences revealed the nature and enormous extent of flagellin diversity. There were 35,898 unique amino acid sequences that were resolved into 187 clusters. Analysis of the Escherichia coli and Salmonella enterica flagellins revealed that the variation occurs at two levels. The first is the division of the variable regions into sequence forms that are so divergent that there is no meaningful alignment even within species, and these corresponded to the E. coli or S. enterica H-antigen groups. The second level is variation within these groups, which is extensive in both species. Shared sequence would allow PCR of the variable regions and thus strain-level analysis of microbiome DNA.
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19
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Aschtgen MS, Brennan CA, Nikolakakis K, Cohen S, McFall-Ngai M, Ruby EG. Insights into flagellar function and mechanism from the squid-vibrio symbiosis. NPJ Biofilms Microbiomes 2019; 5:32. [PMID: 31666982 PMCID: PMC6814793 DOI: 10.1038/s41522-019-0106-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/03/2019] [Indexed: 02/07/2023] Open
Abstract
Flagella are essential and multifunctional nanomachines that not only move symbionts towards their tissue colonization site, but also play multiple roles in communicating with the host. Thus, untangling the activities of flagella in reaching, interacting, and signaling the host, as well as in biofilm formation and the establishment of a persistent colonization, is a complex problem. The squid-vibrio system offers a unique model to study the many ways that bacterial flagella can influence a beneficial association and, generally, other bacteria-host interactions. Vibrio fischeri is a bioluminescent bacterium that colonizes the Hawaiian bobtail squid, Euprymna scolopes. Over the last 15 years, the structure, assembly, and functions of V. fischeri flagella, including not only motility and chemotaxis, but also biofilm formation and symbiotic signaling, have been revealed. Here we discuss these discoveries in the perspective of other host-bacteria interactions.
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Affiliation(s)
- Marie-Stephanie Aschtgen
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706 USA
- Present Address: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Solna, 171 76 Sweden
| | - Caitlin A. Brennan
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706 USA
- Present Address: Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115 USA
| | - Kiel Nikolakakis
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706 USA
- Present Address: Department of Natural and Applied Sciences, University of Wisconsin – Green Bay, Green Bay, WI 54311 USA
| | - Stephanie Cohen
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, and Center for Advanced Surface Analysis, Institute of Earth Sciences, Université de Lausanne, CH-1015 Lausanne, Switzerland
- Kewalo Marine Laboratory, University of Hawaii-Manoa, Honolulu, HI 96813 USA
| | | | - Edward G. Ruby
- Kewalo Marine Laboratory, University of Hawaii-Manoa, Honolulu, HI 96813 USA
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20
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Giacomucci S, Cros CDN, Perron X, Mathieu-Denoncourt A, Duperthuy M. Flagella-dependent inhibition of biofilm formation by sub-inhibitory concentration of polymyxin B in Vibrio cholerae. PLoS One 2019; 14:e0221431. [PMID: 31430343 PMCID: PMC6701800 DOI: 10.1371/journal.pone.0221431] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/06/2019] [Indexed: 01/02/2023] Open
Abstract
Biofilm formation is a common strategy used by bacteria in order to survive and persist in the environment. In Vibrio cholerae (V. cholerae), a Gram-negative pathogen responsible for the cholera disease, biofilm-like aggregates are important for the pathogenesis and disease transmission. Biofilm formation is initiated by the attachment of the bacteria to a surface, followed by maturation stages involving the formation of a biofilm matrix. In V. cholerae, flagella are essential for the initial step of biofilm formation, allowing the bacteria to swim and to detect a surface. In this study, we explored the effect of polymyxin B (PmB), a cationic bacterial antimicrobial peptide, on biofilm formation in pathogenic V. cholerae strains belonging to the O1 and O139 serotypes. We found that sub-inhibitory concentration of PmB induces a reduction of the biofilm formation by V. cholerae O1 and O139. Experiment on preformed biofilm demonstrated that the biofilm formation inhibition occurs at the initial step of biofilm formation, where the flagella are essential. We further characterize the effect of PmB on V. cholerae flagellation. Our results demonstrate that the flagellin expression is not reduced in presence of sub-inhibitory concentration of PmB. However, a decrease of the abundance of flagellin associated with the bacterial cells together with an increase in the secretome was observed. Electron microscopy observations also suggest that the abundance of aflagellated bacteria increases upon PmB supplementation. Finally, in agreement with the effect on the flagellation, a reduction of the bacterial motility is observed. Altogether, our results suggest that the PmB affect V. cholerae flagella resulting in a decrease of the motility and a compromised ability to form biofilm.
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Affiliation(s)
- Sean Giacomucci
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada
| | - Candice Danabé-Nieto Cros
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada
| | - Xavier Perron
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada
| | - Annabelle Mathieu-Denoncourt
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada
| | - Marylise Duperthuy
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada
- * E-mail:
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21
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Abstract
Flagellar filaments of the pathogenic Vibrio species, including V. vulnificus, V. parahaemolyticus, and V. cholerae, are composed of multiple flagellin subunits. In their genomes, however, there are higher numbers of the ORFs encoding flagellin-like proteins than the numbers of flagellin subunits required for filament assembly. Since these flagellin-homologous proteins (FHPs) are well expressed and excreted to environments via a flagellin transport channel, their extracellular role in the pathogenic Vibrio has been enigmatic. Their biological significance, which is not related with flagellar functions, has been revealed to be in maturation of biofilm structures. Among various components of the extracellular polymeric matrix produced in the V. vulnificus biofilms, the exopolysaccharides (EPS) are dominant constituents and crucial in maturation of biofilms. The enhancing role of the V. vulnificus FHPs in biofilm formation requires the presence of EPS, as indicated by highly specific interactions among two FHPs and three EPS. The pathogenic bacterium Vibrio vulnificus exhibits the ability to form biofilm, for which initiation is dependent upon swimming motility by virtue of a polar flagellum. The filament of its flagellum is composed of multiple flagellin subunits, FlaA, -B, -C, and -D. In V. vulnificus genomes, however, open reading frames (ORFs) annotated by FlaE and -F are also present. Although neither FlaE nor FlaF is involved in filament formation and cellular motility, they are well expressed and secreted to the extracellular milieu through the secretion apparatus for flagellar assembly. In the extrapolymeric matrix of V. vulnificus biofilm, significant levels of FlaEF were detected. Mutants defective in both flaE and flaF formed significantly decreased biofilms compared to the wild-type biofilm. Thus, the potential role of FlaEF during the biofilm-forming process was investigated by exogenous addition of recombinant FlaEF (rFlaEF) to the biofilm assays. The added rFlaE and rFlaF were predominantly incorporated into the biofilm matrix formed by the wild type. However, biofilms formed by a mutant defective in exopolysaccharide (EPS) biosynthesis were not affected by added FlaEF. These results raised a possibility that FlaEF specifically interact with EPS within the biofilm matrix. In vitro pulldown assays using His-tagged rFlaEF or rFlaC revealed the specific binding of EPS to rFlaEF but not to rFlaC. Taken together, our results demonstrate that V. vulnificus FlaEF, flagellin-homologous proteins (FHPs), are crucial for biofilm formation by directly interacting with the essential determinant for biofilm maturation, EPS. Further analyses performed with other pathogenic Vibrio species demonstrated both the presence of FHPs and their important role in biofilm formation.
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22
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Khider M, Hansen H, Hjerde E, Johansen JA, Willassen NP. Exploring the transcriptome of luxI- and ΔainS mutants and the impact of N-3-oxo-hexanoyl-L- and N-3-hydroxy-decanoyl-L-homoserine lactones on biofilm formation in Aliivibrio salmonicida. PeerJ 2019; 7:e6845. [PMID: 31106062 PMCID: PMC6499059 DOI: 10.7717/peerj.6845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/18/2019] [Indexed: 01/12/2023] Open
Abstract
Background Bacterial communication through quorum sensing (QS) systems has been reported to be important in coordinating several traits such as biofilm formation. In Aliivibrio salmonicida two QS systems the LuxI/R and AinS/R, have been shown to be responsible for the production of eight acyl-homoserine lactones (AHLs) in a cell density dependent manner. We have previously demonstrated that inactivation of LitR, the master regulator of the QS system resulted in biofilm formation, similar to the biofilm formed by the AHL deficient mutant ΔainSluxI−. In this study, we aimed to investigate the global gene expression patterns of luxI and ainS autoinducer synthases mutants using transcriptomic profiling. In addition, we examined the influence of the different AHLs on biofilm formation. Results The transcriptome profiling of ΔainS and luxI− mutants allowed us to identify genes and gene clusters regulated by QS in A. salmonicida. Relative to the wild type, the ΔainS and luxI− mutants revealed 29 and 500 differentially expressed genes (DEGs), respectively. The functional analysis demonstrated that the most pronounced DEGs were involved in bacterial motility and chemotaxis, exopolysaccharide production, and surface structures related to adhesion. Inactivation of luxI, but not ainS genes resulted in wrinkled colony morphology. While inactivation of both genes (ΔainSluxI−) resulted in strains able to form wrinkled colonies and mushroom structured biofilm. Moreover, when the ΔainSluxI− mutant was supplemented with N-3-oxo-hexanoyl-L-homoserine lactone (3OC6-HSL) or N-3-hydroxy-decanoyl-L-homoserine lactone (3OHC10-HSL), the biofilm did not develop. We also show that LuxI is needed for motility and for repression of EPS production, where repression of EPS is likely operated through the RpoQ-sigma factor. Conclusion These findings imply that the LuxI and AinS autoinducer synthases play a critical role in the regulation of biofilm formation, EPS production, and motility.
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Affiliation(s)
- Miriam Khider
- Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Hilde Hansen
- Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Erik Hjerde
- Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway.,Centre for Bioinformatics, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Jostein A Johansen
- Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Nils Peder Willassen
- Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway.,Centre for Bioinformatics, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway
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Echazarreta MA, Klose KE. Vibrio Flagellar Synthesis. Front Cell Infect Microbiol 2019; 9:131. [PMID: 31119103 PMCID: PMC6504787 DOI: 10.3389/fcimb.2019.00131] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 04/12/2019] [Indexed: 12/31/2022] Open
Abstract
Vibrio spp. are highly motile Gram-negative bacteria, ubiquitously found in aquatic environments. Some Vibrios are responsible for disease and morbidity of marine invertebrates and humans, while others are studied for their symbiotic interactions. Vibrio spp. are motile due to synthesis of flagella that rotate and propel the bacteria. Many Vibrio spp. synthesize monotrichous polar flagella (e.g., V. cholerae, V. alginolyticus); however, some synthesize peritrichous or lophotrichous flagella. Flagellar-mediated motility is intimately connected to biological and cellular processes such as chemotaxis, biofilm formation, colonization, and virulence of Vibrio spp. This review focuses on the polar flagellum and its regulation in regard to Vibrio virulence and environmental persistence.
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Affiliation(s)
- Mylea A Echazarreta
- Department of Biology, South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Karl E Klose
- Department of Biology, South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
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24
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Khider M, Hjerde E, Hansen H, Willassen NP. Differential expression profiling of ΔlitR and ΔrpoQ mutants reveals insight into QS regulation of motility, adhesion and biofilm formation in Aliivibrio salmonicida. BMC Genomics 2019; 20:220. [PMID: 30876404 PMCID: PMC6420764 DOI: 10.1186/s12864-019-5594-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 03/11/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The coordination of group behaviors in bacteria is achieved by a cell-cell signaling process called quorum sensing (QS). QS is an intercellular communication system, which synchronously controls expression of a vast range of genes in response to changes in cell density and is mediated by autoinducers that act as extracellular signals. Aliivibrio salmonicida, the causative agent of cold-water vibrosis in marine aquacultures, uses QS to regulate several activities such as motility, biofilm formation, adhesion and rugose colony morphology. However, little is known about either genes or detailed mechanisms involved in the regulation of these phenotypes. RESULTS Differential expression profiling allowed us to define the genes involved in controlling phenotypes related to QS in A. salmonicida LFI1238. RNA sequencing data revealed that the number of expressed genes in A. salmonicida, ΔlitR and ΔrpoQ mutants were significantly altered due to changes in cell density. These included genes that were distributed among the 21 functional groups, mainly presented in cell envelope, cell processes, extrachromosomal/foreign DNA and transport-binding proteins functional groups. The comparative transcriptome of A. salmonicida wild-type at high cell density relative to low cell density revealed 1013 genes to be either up- or downregulated. Thirty-six downregulated genes were gene clusters encoding biosynthesis of the flagellar and chemotaxis genes. Additionally we identified significant expression for genes involved in acyl homoserine lactone (AHL) synthesis, adhesion and early colonization. The transcriptome profile of ΔrpoQ compared to the wild-type revealed 384 differensially expressed genes (DEGs) that allowed us to assign genes involved in regulating motility, adhesion and colony rugosity. Indicating the importance of RpoQ in controlling several QS related activities. Furthermore, the comparison of the transcriptome profiles of ΔlitR and ΔrpoQ mutants, exposed numerous overlapping DEGs that were essential for motility, exopolysaccharide production via syp operon and genes associated with tad operon. CONCLUSION Our findings indicate previously unexplained functional roles for LitR and RpoQ in regulation of different phenotypes related to QS. Our transcriptome data provide a better understanding of the regulation cascade of motility, wrinkling colony morphology and biofilm formation and will offer a major source for further research and analysis on this important field.
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Affiliation(s)
- Miriam Khider
- Norwegian Structural Biology Centre, UiT - The Arctic University of Norway, N-9037, Tromsø, Norway.
| | - Erik Hjerde
- Norwegian Structural Biology Centre, UiT - The Arctic University of Norway, N-9037, Tromsø, Norway.,Centre for Bioinformatics, Department of Chemistry, Faculty of Science and Technology, UiT - The Arctic University of Norway, N-9037, Tromsø, Norway
| | - Hilde Hansen
- Norwegian Structural Biology Centre, UiT - The Arctic University of Norway, N-9037, Tromsø, Norway
| | - Nils Peder Willassen
- Norwegian Structural Biology Centre, UiT - The Arctic University of Norway, N-9037, Tromsø, Norway. .,Centre for Bioinformatics, Department of Chemistry, Faculty of Science and Technology, UiT - The Arctic University of Norway, N-9037, Tromsø, Norway.
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Kühn MJ, Schmidt FK, Farthing NE, Rossmann FM, Helm B, Wilson LG, Eckhardt B, Thormann KM. Spatial arrangement of several flagellins within bacterial flagella improves motility in different environments. Nat Commun 2018; 9:5369. [PMID: 30560868 PMCID: PMC6299084 DOI: 10.1038/s41467-018-07802-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 11/22/2018] [Indexed: 11/26/2022] Open
Abstract
Bacterial flagella are helical proteinaceous fibers, composed of the protein flagellin, that confer motility to many bacterial species. The genomes of about half of all flagellated species include more than one flagellin gene, for reasons mostly unknown. Here we show that two flagellins (FlaA and FlaB) are spatially arranged in the polar flagellum of Shewanella putrefaciens, with FlaA being more abundant close to the motor and FlaB in the remainder of the flagellar filament. Observations of swimming trajectories and numerical simulations demonstrate that this segmentation improves motility in a range of environmental conditions, compared to mutants with single-flagellin filaments. In particular, it facilitates screw-like motility, which enhances cellular spreading through obstructed environments. Similar mechanisms may apply to other bacterial species and may explain the maintenance of multiple flagellins to form the flagellar filament.
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Affiliation(s)
- Marco J Kühn
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Gießen, 35392, Gießen, Germany
| | - Felix K Schmidt
- Fachbereich Physik und LOEWE Zentrum für Synthetische Mikrobiologie, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Nicola E Farthing
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
- Department of Mathematics, University of York, Heslington, York, YO10 5DD, UK
| | - Florian M Rossmann
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Gießen, 35392, Gießen, Germany
| | - Bina Helm
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Gießen, 35392, Gießen, Germany
| | - Laurence G Wilson
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK.
| | - Bruno Eckhardt
- Fachbereich Physik und LOEWE Zentrum für Synthetische Mikrobiologie, Philipps-Universität Marburg, 35032, Marburg, Germany.
| | - Kai M Thormann
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Gießen, 35392, Gießen, Germany.
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Transcriptional profiling of the mutualistic bacterium Vibrio fischeri and an hfq mutant under modeled microgravity. NPJ Microgravity 2018; 4:25. [PMID: 30588486 PMCID: PMC6299092 DOI: 10.1038/s41526-018-0060-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 11/05/2018] [Indexed: 02/06/2023] Open
Abstract
For long-duration space missions, it is critical to maintain health-associated homeostasis between astronauts and their microbiome. To achieve this goal it is important to more fully understand the host–symbiont relationship under the physiological stress conditions of spaceflight. To address this issue we examined the impact of a spaceflight analog, low-shear-modeled microgravity (LSMMG), on the transcriptome of the mutualistic bacterium Vibrio fischeri. Cultures of V. fischeri and a mutant defective in the global regulator Hfq (∆hfq) were exposed to either LSMMG or gravity conditions for 12 h (exponential growth) and 24 h (stationary phase growth). Comparative transcriptomic analysis revealed few to no significant differentially expressed genes between gravity and the LSMMG conditions in the wild type or mutant V. fischeri at exponential or stationary phase. There was, however, a pronounced change in transcriptomic profiles during the transition between exponential and stationary phase growth in both V. fischeri cultures including an overall decrease in gene expression associated with translational activity and an increase in stress response. There were also several upregulated stress genes specific to the LSMMG condition during the transition to stationary phase growth. The ∆hfq mutants exhibited a distinctive transcriptome profile with a significant increase in transcripts associated with flagellar synthesis and transcriptional regulators under LSMMG conditions compared to gravity controls. These results indicate the loss of Hfq significantly influences gene expression under LSMMG conditions in a bacterial symbiont. Together, these results improve our understanding of the mechanisms by which microgravity alters the physiology of beneficial host-associated microbes.
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Multiple Flagellin Proteins Have Distinct and Synergistic Roles in Agrobacterium tumefaciens Motility. J Bacteriol 2018; 200:JB.00327-18. [PMID: 30201783 DOI: 10.1128/jb.00327-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 09/01/2018] [Indexed: 11/20/2022] Open
Abstract
Rotary flagella propel bacteria through liquid and across semisolid environments. Flagella are composed of the basal body that constitutes the motor for rotation, the curved hook that connects to the basal body, and the flagellar filament that propels the cell. Flagellar filaments can be composed of a single flagellin protein, such as in Escherichia coli, or made up of multiple flagellins, such as in Agrobacterium tumefaciens The four distinct flagellins FlaA, FlaB, FlaC, and FlaD produced by wild-type A. tumefaciens are not redundant in function but have specific properties. FlaA and FlaB are much more abundant than FlaC and FlaD and are readily observable in mature flagellar filaments, when either FlaA or FlaB is fluorescently labeled. Cells producing FlaA with any one of the other three flagellins can generate functional filaments and thus are motile, but FlaA alone cannot constitute a functional filament. In flaA mutants that manifest swimming deficiencies, there are multiple ways by which these mutations can be phenotypically suppressed. These suppressor mutations primarily occur within or upstream of the flaB flagellin gene or in the transcription factor sciP regulating flagellin expression. The helical conformation of the flagellar filament appears to require a key asparagine residue present in FlaA and absent in other flagellins. However, FlaB can be spontaneously mutated to render helical flagella in the absence of FlaA, reflecting their overall similarity and perhaps the subtle differences in the specific functions they have evolved to fulfill.IMPORTANCE Flagellins are abundant bacterial proteins comprising the flagellar filaments that propel bacterial movement. Several members of the alphaproteobacterial group express multiple flagellins, in contrast to model systems, such as with Escherichia coli, which has one type of flagellin. The plant pathogen Agrobacterium tumefaciens has four flagellins, the abundant and readily detected FlaA and FlaB, and lower levels of FlaC and FlaD. Mutational analysis reveals that FlaA requires at least one of the other flagellins to function, as flaA mutants produce nonhelical flagella and cannot swim efficiently. Suppressor mutations can rescue this swimming defect through mutations in the remaining flagellins, including structural changes imparting helical shape to the flagella, and putative regulators. Our findings shed light on how multiple flagellins contribute to motility.
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Echazarreta MA, Kepple JL, Yen LH, Chen Y, Klose KE. A Critical Region in the FlaA Flagellin Facilitates Filament Formation of the Vibrio cholerae Flagellum. J Bacteriol 2018; 200:e00029-18. [PMID: 29581407 PMCID: PMC6040194 DOI: 10.1128/jb.00029-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/10/2018] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae is a Gram-negative bacterium with a monotrichous flagellum that causes the human disease cholera. Flagellum-mediated motility is an integral part of the bacterial life cycle inside the host and in the aquatic environment. The V. cholerae flagellar filament is composed of five flagellin subunits (FlaA, FlaB, FlaC, FlaD, and FlaE); however, only FlaA is necessary and sufficient for filament synthesis. flaA is transcribed from a class III flagellar promoter, whereas the other four flagellins are transcribed from class IV promoters. However, expressing flaA from a class IV promoter still facilitated motility in a strain that was otherwise lacking all five flagellins (ΔflaA-E). Furthermore, FlaA from V. parahaemolyticus (FlaAVP; 77% identity) supported motility of the V. cholerae ΔflaA-E strain, whereas FlaA from V. vulnificus (FlaAVV; 75% identity) did not, indicating that FlaA amino acid sequence is responsible for its critical role in flagellar synthesis. Chimeric proteins composed of different domains of FlaAVC and FlaD or FlaAVV revealed that the N-terminal D1 domain (D1N) contains an important region required for FlaA function. Further analyses of chimeric FlaAVC-FlaD proteins identified a lysine residue present at position 145 of the other flagellins but absent from FlaAVC that can prevent monofilament formation. Moreover, the D1N region of amino acids 87 to 153 of FlaAVV inserted into FlaAVC allows monofilament formation but not motility, apparently due to the lack of filament curvature. These results identify residues within the D1N domain that allow FlaAVC to fold into a functional filament structure and suggest that FlaAVC assists correct folding of the other flagellins.IMPORTANCEV. cholerae causes the severe diarrheal disease cholera. Its ability to swim is mediated by rotation of a polar flagellum, and this motility is integral to its ability to cause disease and persist in the environment. The current studies illuminate how one specific flagellin (FlaA) within a multiflagellin structure mediates formation of the flagellar filament, thus allowing V. cholerae to swim. This knowledge can lead to safer vaccines and potential therapeutics to inhibit cholera.
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Affiliation(s)
- Mylea A Echazarreta
- South Texas Center for Emerging Infectious Diseases, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, USA
| | - Johnathan L Kepple
- South Texas Center for Emerging Infectious Diseases, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, USA
| | - Li-Hua Yen
- South Texas Center for Emerging Infectious Diseases, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, USA
| | - Yue Chen
- South Texas Center for Emerging Infectious Diseases, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, USA
| | - Karl E Klose
- South Texas Center for Emerging Infectious Diseases, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, USA
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Kinosita Y, Nishizaka T. Cross-kymography analysis to simultaneously quantify the function and morphology of the archaellum. Biophys Physicobiol 2018; 15:121-128. [PMID: 29955563 PMCID: PMC6018435 DOI: 10.2142/biophysico.15.0_121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 03/29/2018] [Indexed: 12/13/2022] Open
Abstract
In many microorganisms helical structures are important for motility, e.g., bacterial flagella and kink propagation in Spiroplasma eriocheiris. Motile archaea also form a helical-shaped filament called the ‘archaellum’ that is functionally equivalent to the bacterial flagellum, but structurally resembles type IV pili. The archaellum motor consists of 6–8 proteins called fla accessory genes, and the filament assembly is driven by ATP hydrolysis at catalytic sites in FlaI. Remarkably, previous research using a dark-field microscopy showed that right-handed filaments propelled archaeal cells forwards or backwards by clockwise or counterclockwise rotation, respectively. However, the shape and rotational rate of the archaellum during swimming remained unclear, due to the low signal and lack of temporal resolution. Additionally, the structure and the motor properties of the archaellum and bacterial flagellum have not been precisely determined during swimming because they move freely in three-dimensional space. Recently, we developed an advanced method called “cross-kymography analysis”, which enables us to be a long-term observation and simultaneously quantify the function and morphology of helical structures using a total internal reflection fluorescence microscope. In this review, we introduce the basic idea of this analysis, and summarize the latest information in structural and functional characterization of the archaellum motor.
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Affiliation(s)
- Yoshiaki Kinosita
- Department of Physics, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Takayuki Nishizaka
- Department of Physics, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
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Pang H, Qiu M, Zhao J, Hoare R, Monaghan SJ, Song D, Chang Y, Jian J. Construction of a Vibrio alginolyticus hopPmaJ (hop) mutant and evaluation of its potential as a live attenuated vaccine in orange-spotted grouper (Epinephelus coioides). FISH & SHELLFISH IMMUNOLOGY 2018; 76:93-100. [PMID: 29427720 DOI: 10.1016/j.fsi.2018.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/31/2018] [Accepted: 02/06/2018] [Indexed: 06/08/2023]
Abstract
Vibrio alginolyticus, a bacterial pathogen in fish and humans, expresses a type III secretion system (T3SS) that is critical for pathogen virulence and disease development. However, little is known about the associated effectors (T3SEs) and their physiological role. In this study, the T3SE gene hopPmaJ (hop) was cloned from V. alginolyticus wild-type strain HY9901 and the mutant strain HY9901Δhop was constructed by the in-frame deletion method. The results showed that the deduced amino acid sequence of V. alginolyticus HopPmaJ shared 78-98% homology with other Vibrio spp. In addition, the HY9901Δhop mutant showed an attenuated swarming phenotype and a 2600-fold decrease in the virulence to grouper. However, the HY9901Δhop mutant showed no difference in morphology, growth, biofilm formation and ECPase activity. Finally, grouper vaccinated via intraperitoneal (IP) injection with HY9901Δhop induced a high antibody titer with a relative percent survival (RPS) value of 84% after challenging with the wild-type HY9901. Real-time PCR assays showed that vaccination with HY9901Δhop enhanced the expression of immune-related genes, including MHC-Iα, MHC-IIα, IgM, and IL-1β after vaccination, indicating that it is able to induce humoral and cell-mediated immune response in grouper. These results demonstrate that the HY9901Δhop mutant could be used as an effective live vaccine to combat V. alginolyticus in grouper.
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Affiliation(s)
- Huanying Pang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524025, China; Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524025, China; Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524025, China
| | - Mingsheng Qiu
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524025, China
| | - Jingmin Zhao
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524025, China
| | - Rowena Hoare
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Sean J Monaghan
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Dawei Song
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524025, China; Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524025, China; Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524025, China
| | - Yunsheng Chang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524025, China; Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524025, China; Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524025, China
| | - Jichang Jian
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524025, China; Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524025, China; Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524025, China.
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Cai S, Cheng H, Pang H, Jian J, Wu Z. AcfA is an essential regulator for pathogenesis of fish pathogen Vibrio alginolyticus. Vet Microbiol 2017; 213:35-41. [PMID: 29292001 DOI: 10.1016/j.vetmic.2017.11.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 09/25/2017] [Accepted: 11/17/2017] [Indexed: 12/22/2022]
Abstract
V. alginolyticus is an important opportunistic pathogen which causes vibriosis in aquatic animals. AcfA, as an accessory colonization factor, is hypothesized to be involved in the pathogenesis of infection. In this study, a mutant strain with an in-frame deletion removed nucleotides 86 to 561 of the acfA gene was constructed to reveal the role of AcfA in the physiology and virulence from V. alginolyticus. An acfA mutant showed a similar growth level, an obvious decrease in swarming motility and the activity of ECPase, a higher LD50 value by intraperitoneal injection of grouper fish compared to that of the wild-type. Furthermore, the deletion of acfA could enhance the level of biofilm formation and suppress the polar flagellum forming. The comparative proteomic analysis demonstrated the deletion mutation of acfA could up-regulate the expression of 4 proteins of p4alcd, deoD, phb and DctP, and down-regulate the expression of 8 proteins of Clp, hpV36980, ABCtp, pepD, arA, aggp, fla and ompA compared to that of the wild-type. The analysis of RT-qPCR showed the mRNA levels of DctP and deoD were significantly induced, and the mRNA levels of pepD, arA, fla and ompA were significantly reduced in acfA mutant compared with the wild-type. The results suggest that acfA may contribute to the overall success in the pathogenesis of V. alginolyticus by regulating the expression of some relevant genes.
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Affiliation(s)
- Shuanghu Cai
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Fisheries College of Guangdong Ocean University, Zhanjiang, China.
| | - Haiyan Cheng
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Huanying Pang
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Jichang Jian
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Zaohe Wu
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Fisheries College of Guangdong Ocean University, Zhanjiang, China
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Abstract
The coordination of group behaviors in bacteria is accomplished via the cell-cell signaling process called quorum sensing. Vibrios have historically been models for studying bacterial communication due to the diverse and remarkable behaviors controlled by quorum sensing in these bacteria, including bioluminescence, type III and type VI secretion, biofilm formation, and motility. Here, we discuss the Vibrio LuxR/HapR family of proteins, the master global transcription factors that direct downstream gene expression in response to changes in cell density. These proteins are structurally similar to TetR transcription factors but exhibit distinct biochemical and genetic features from TetR that determine their regulatory influence on the quorum sensing gene network. We review here the gene groups regulated by LuxR/HapR and quorum sensing and explore the targets that are common and unique among Vibrio species.
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Nørstebø SF, Paulshus E, Bjelland AM, Sørum H. A unique role of flagellar function in Aliivibrio salmonicida pathogenicity not related to bacterial motility in aquatic environments. Microb Pathog 2017; 109:263-273. [PMID: 28602841 DOI: 10.1016/j.micpath.2017.06.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/01/2017] [Accepted: 06/06/2017] [Indexed: 12/21/2022]
Abstract
Aliivibrio salmonicida is the causative agent of cold-water vibriosis, a septicemia of farmed salmonid fish. The mechanisms of disease are not well described, and few virulence factors have been identified. However, a requirement for motility in the pathogenesis has been reported. Al. salmonicida is motile by the means of lophotrichous polar flagella, consisting of multiple flagellin subunits that are expressed simultaneously. Here we show that flagellin subunit FlaA, but not FlaD, is of major importance for motility in Al. salmonicida. Deletion of flaA resulted in 62% reduction in motility, as well as a reduction in the fraction of flagellated cells and number of flagella per cell. Similarly, deletion of the gene encoding motor protein motA gave rise to an aflagellate phenotype and cessation of motility. Surprisingly, we found that Al. salmonicida does not require motility for invasion of Atlantic salmon. Nevertheless, in-frame deletion mutants defective of motA and flaA were less virulent in Atlantic salmon challenged by immersion, whereas an effect on virulence after i.p. challenge was only seen for the latter. Our results indicate a complex requirement for motility and/or flagellation in the pathogenesis of cold-water vibriosis, but the mechanisms involved remain unknown. We hypothesize that the differences in virulence observed after immersion and i.p. challenge are related to the immune response of the host.
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Affiliation(s)
- Simen Foyn Nørstebø
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway.
| | - Erik Paulshus
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway.
| | - Ane Mohn Bjelland
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway.
| | - Henning Sørum
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway.
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Mandel MJ, Dunn AK. Impact and Influence of the Natural Vibrio-Squid Symbiosis in Understanding Bacterial-Animal Interactions. Front Microbiol 2016; 7:1982. [PMID: 28018314 PMCID: PMC5156696 DOI: 10.3389/fmicb.2016.01982] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/25/2016] [Indexed: 11/13/2022] Open
Abstract
Animals are colonized by bacteria, and in many cases partners have co-evolved to perform mutually beneficial functions. An exciting and ongoing legacy of the past decade has been an expansion of technology to enable study of natural associations in situ/in vivo. As a result, more symbioses are being examined, and additional details are being revealed for well-studied systems with a focus on the interactions between partners in the native context. With this framing, we review recent literature from the Vibrio fischeri-Euprymna scolopes symbiosis and focus on key studies that have had an impact on understanding bacteria-animal interactions broadly. This is not intended to be a comprehensive review of the system, but rather to focus on particular studies that have excelled at moving from pattern to process in facilitating an understanding of the molecular basis to intriguing observations in the field of host-microbe interactions. In this review we discuss the following topics: processes regulating strain and species specificity; bacterial signaling to host morphogenesis; multiple roles for nitric oxide; flagellar motility and chemotaxis; and efforts to understand unannotated and poorly annotated genes. Overall these studies demonstrate how functional approaches in vivo in a tractable system have provided valuable insight into general principles of microbe-host interactions.
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Affiliation(s)
- Mark J Mandel
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine Chicago, IL, USA
| | - Anne K Dunn
- Department of Microbiology and Plant Biology, University of Oklahoma Norman, OK, USA
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Rotation of Vibrio fischeri Flagella Produces Outer Membrane Vesicles That Induce Host Development. J Bacteriol 2016; 198:2156-65. [PMID: 27246572 DOI: 10.1128/jb.00101-16] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/20/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Using the squid-vibrio association, we aimed to characterize the mechanism through which Vibrio fischeri cells signal morphogenesis of the symbiotic light-emitting organ. The symbiont releases two cell envelope molecules, peptidoglycan (PG) and lipopolysaccharide (LPS) that, within 12 h of light organ colonization, act in synergy to trigger normal tissue development. Recent work has shown that outer membrane vesicles (OMVs) produced by V. fischeri are sufficient to induce PG-dependent morphogenesis; however, the mechanism(s) of OMV release by these bacteria has not been described. Like several genera of both beneficial and pathogenic bacteria, V. fischeri cells elaborate polar flagella that are enclosed by an extension of the outer membrane, whose function remains unclear. Here, we present evidence that along with the well-recognized phenomenon of blebbing from the cell's surface, rotation of this sheathed flagellum also results in the release of OMVs. In addition, we demonstrate that most of the development-inducing LPS is associated with these OMVs and that the presence of the outer membrane protein OmpU but not the LPS O antigen on these OMVs is important in triggering normal host development. These results also present insights into a possible new mechanism of LPS release by pathogens with sheathed flagella. IMPORTANCE Determining the function(s) of sheathed flagella in bacteria has been challenging, because no known mutation results only in the loss of this outer membrane-derived casing. Nevertheless, the presence of a sheathed flagellum in such host-associated genera as Vibrio, Helicobacter, and Brucella has led to several proposed functions, including physical protection of the flagella and masking of their immunogenic flagellins. Using the squid-vibrio light organ symbiosis, we demonstrate another role, that of V. fischeri cells require rotating flagella to induce apoptotic cell death within surface epithelium, which is a normal step in the organ's development. Further, we present evidence that this rotation releases apoptosis-triggering lipopolysaccharide in the form of outer membrane vesicles. Such release may also occur by pathogens but with different outcomes for the host.
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Chavez-Dozal A, Gorman C, Nishiguchi MK. Proteomic and metabolomic profiles demonstrate variation among free-living and symbiotic vibrio fischeri biofilms. BMC Microbiol 2015; 15:226. [PMID: 26494154 PMCID: PMC4619220 DOI: 10.1186/s12866-015-0560-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 10/08/2015] [Indexed: 11/11/2022] Open
Abstract
Background A number of bacterial species are capable of growing in various life history modes that enable their survival and persistence in both planktonic free-living stages as well as in biofilm communities. Mechanisms contributing to either planktonic cell or biofilm persistence and survival can be carefully delineated using multiple differential techniques (e.g., genomics and transcriptomics). In this study, we present both proteomic and metabolomic analyses of Vibrio fischeri biofilms, demonstrating the potential for combined differential studies for elucidating life-history switches important for establishing the mutualism through biofilm formation and host colonization. Methods The study used a metabolomics/proteomics or “meta-proteomics” approach, referring to the combined protein and metabolic data analysis that bridges the gap between phenotypic changes (planktonic cell to biofilm formation) with genotypic changes (reflected in protein/metabolic profiles). Our methods used protein shotgun construction, followed by liquid chromatography coupled with mass spectrometry (LC-MS) detection and quantification for both free-living and biofilm forming V. fischeri. Results We present a time-resolved picture of approximately 100 proteins (2D-PAGE and shotgun proteomics) and 200 metabolites that are present during the transition from planktonic growth to community biofilm formation. Proteins involved in stress response, DNA repair damage, and transport appeared to be highly expressed during the biofilm state. In addition, metabolites detected in biofilms correspond to components of the exopolysaccharide (EPS) matrix (sugars and glycerol-derived). Alterations in metabolic enzymes were paralleled by more pronounced changes in concentration of intermediates from the glycolysis pathway as well as several amino acids. Conclusions This combined analysis of both types of information (proteins, metabolites) has provided a more complete picture of the biochemical processes of biofilm formation and what determines the switch between the two life history strategies. The reported findings have broad implications for Vibrio biofilm ecology, and mechanisms for successful survival in the host and environment. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0560-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alba Chavez-Dozal
- Department of Biology, New Mexico State University, Box 30001, MSC 3AF, Las Cruces, NM, 88003-8001, USA.
| | - Clayton Gorman
- Department of Biology, New Mexico State University, Box 30001, MSC 3AF, Las Cruces, NM, 88003-8001, USA.
| | - Michele K Nishiguchi
- Department of Biology, New Mexico State University, Box 30001, MSC 3AF, Las Cruces, NM, 88003-8001, USA.
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Lee JB, Byeon JH, Jang HA, Kim JK, Yoo JW, Kikuchi Y, Lee BL. Bacterial cell motility of Burkholderia gut symbiont is required to colonize the insect gut. FEBS Lett 2015; 589:2784-90. [PMID: 26318755 DOI: 10.1016/j.febslet.2015.08.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/14/2015] [Accepted: 08/17/2015] [Indexed: 01/08/2023]
Abstract
We generated a Burkholderia mutant, which is deficient of an N-acetylmuramyl-l-alanine amidase, AmiC, involved in peptidoglycan degradation. When non-motile ΔamiC mutant Burkholderia cells harboring chain form were orally administered to Riptortus insects, ΔamiC mutant cells were unable to establish symbiotic association. But, ΔamiC mutant complemented with amiC gene restored in vivo symbiotic association. ΔamiC mutant cultured in minimal medium restored their motility with single-celled morphology. When ΔamiC mutant cells harboring single-celled morphology were administered to the host insect, this mutant established normal symbiotic association, suggesting that bacterial motility is essential for the successful symbiosis between host insect and Burkholderia symbiont.
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Affiliation(s)
- Jun Beom Lee
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Busan 609-735, South Korea
| | - Jin Hee Byeon
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Busan 609-735, South Korea
| | - Ho Am Jang
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Busan 609-735, South Korea
| | - Jiyeun Kate Kim
- Department of Microbiology, Kosin University College of Medicine, Busan 602-703, South Korea
| | - Jin Wook Yoo
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Busan 609-735, South Korea
| | - Yoshitomo Kikuchi
- Bioproduction Research Institute, Hokkaido Center, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo 062-8517, Japan
| | - Bok Luel Lee
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Busan 609-735, South Korea.
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Soto W, Nishiguchi MK. Microbial experimental evolution as a novel research approach in the Vibrionaceae and squid-Vibrio symbiosis. Front Microbiol 2014; 5:593. [PMID: 25538686 PMCID: PMC4260504 DOI: 10.3389/fmicb.2014.00593] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 10/20/2014] [Indexed: 12/21/2022] Open
Abstract
The Vibrionaceae are a genetically and metabolically diverse family living in aquatic habitats with a great propensity toward developing interactions with eukaryotic microbial and multicellular hosts (as either commensals, pathogens, and mutualists). The Vibrionaceae frequently possess a life history cycle where bacteria are attached to a host in one phase and then another where they are free from their host as either part of the bacterioplankton or adhered to solid substrates such as marine sediment, riverbeds, lakebeds, or floating particulate debris. These two stages in their life history exert quite distinct and separate selection pressures. When bound to solid substrates or to host cells, the Vibrionaceae can also exist as complex biofilms. The association between bioluminescent Vibrio spp. and sepiolid squids (Cephalopoda: Sepiolidae) is an experimentally tractable model to study bacteria and animal host interactions, since the symbionts and squid hosts can be maintained in the laboratory independently of one another. The bacteria can be grown in pure culture and the squid hosts raised gnotobiotically with sterile light organs. The partnership between free-living Vibrio symbionts and axenic squid hatchlings emerging from eggs must be renewed every generation of the cephalopod host. Thus, symbiotic bacteria and animal host can each be studied alone and together in union. Despite virtues provided by the Vibrionaceae and sepiolid squid-Vibrio symbiosis, these assets to evolutionary biology have yet to be fully utilized for microbial experimental evolution. Experimental evolution studies already completed are reviewed, along with exploratory topics for future study.
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Affiliation(s)
- William Soto
- BEACON Center for the Study of Evolution in Action, Michigan State UniversityEast Lansing, MI, USA
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Ondrey JM, Visick KL. Engineering Vibrio fischeri for Inducible Gene Expression. Open Microbiol J 2014; 8:122-9. [PMID: 25408777 PMCID: PMC4235076 DOI: 10.2174/1874285801408010122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 09/19/2014] [Accepted: 09/29/2014] [Indexed: 11/30/2022] Open
Abstract
The marine bacterium Vibrio fischeri serves as a model organism for a variety of natural phenomena, including symbiotic host colonization. The ease with which the V. fischeri genome can be manipulated contributes greatly to our ability to identify the factors involved in these phenomena. Here, we have adapted genetic tools for use in V. fischeri to promote our ability to conditionally control the expression of genes of interest. Specifically, we modified the commonly used mini-Tn5 transposon to contain an outward-facing, LacI-repressible/IPTG-inducible promoter, and inserted the lacI gene into the V. fischeri chromosome. Used together, these tools permit the identification and induction of genes that control specific phenotypes. To validate this approach, we identified IPTG-controllable motility mutants. We anticipate that the ability to randomly insert an inducible promoter into the genome of V. fischeri will advance our understanding of various aspects of the physiology of this microbe.
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Affiliation(s)
- Jakob M Ondrey
- Department of Microbiology and Immunology, Health Sciences Division, Loyola University Chicago, 2160 S. First Avenue Building 105 Room 3936, Maywood, IL 60153, USA
| | - Karen L Visick
- Department of Microbiology and Immunology, Health Sciences Division, Loyola University Chicago, 2160 S. First Avenue Building 105 Room 3936, Maywood, IL 60153, USA
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Shapiro JW, Turner PE. The impact of transmission mode on the evolution of benefits provided by microbial symbionts. Ecol Evol 2014; 4:3350-61. [PMID: 25535552 PMCID: PMC4228610 DOI: 10.1002/ece3.1166] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 06/13/2014] [Accepted: 06/19/2014] [Indexed: 01/05/2023] Open
Abstract
While past work has often examined the effects of transmission mode on virulence evolution in parasites, few studies have explored the impact of horizontal transmission on the evolution of benefits conferred by a symbiont to its host. Here, we identify three mechanisms that create a positive covariance between horizontal transmission and symbiont-provided benefits: pleiotropy within the symbiont genome, partner choice by the host, and consumption of host waste by-products by symbionts. We modify a susceptible-infected model to incorporate the details of each mechanism and examine the evolution of symbiont benefits given variation in either the immigration rate of susceptible hosts or the rate of successful vertical transmission. We find conditions for each case under which greater opportunity for horizontal transmission (higher migration rate) favors the evolution of mutualism. Further, we find the surprising result that vertical transmission can inhibit the evolution of benefits provided by symbionts to hosts when horizontal transmission and symbiont-provided benefits are positively correlated. These predictions may apply to a number of natural systems, and the results may explain why many mutualisms that rely on partner choice often lack a mechanism for vertical transmission.
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Affiliation(s)
- Jason W Shapiro
- Department of Ecology & Evolutionary Biology, Yale University New Haven, Connecticut
| | - Paul E Turner
- Department of Ecology & Evolutionary Biology, Yale University New Haven, Connecticut
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Brennan CA, Hunt JR, Kremer N, Krasity BC, Apicella MA, McFall-Ngai MJ, Ruby EG. A model symbiosis reveals a role for sheathed-flagellum rotation in the release of immunogenic lipopolysaccharide. eLife 2014; 3:e01579. [PMID: 24596150 PMCID: PMC3941163 DOI: 10.7554/elife.01579] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bacterial flagella mediate host–microbe interactions through tissue tropism during colonization, as well as by activating immune responses. The flagellar shaft of some bacteria, including several human pathogens, is encased in a membranous sheath of unknown function. While it has been hypothesized that the sheath may allow these bacteria to evade host responses to the immunogenic flagellin subunit, this unusual structural feature has remained an enigma. Here we demonstrate that the rotation of the sheathed flagellum in both the mutualist Vibrio fischeri and the pathogen Vibrio cholerae promotes release of a potent bacteria-derived immunogen, lipopolysaccharide, found in the flagellar sheath. We further present a new role for the flagellar sheath in triggering, rather than circumventing, host immune responses in the model squid-vibrio symbiosis. Such an observation not only has implications for the study of bacterial pathogens with sheathed flagella, but also raises important biophysical questions of sheathed-flagellum function. DOI:http://dx.doi.org/10.7554/eLife.01579.001 While a few of the bacteria that live in and on the bodies of humans and other animals are harmful and can cause disease, most others can offer benefits to their hosts. Many bacteria—including some important human pathogens—have tails called flagella that rotate to move the bacteria inside its host. However, the immune system can detect parts of these flagella and eliminate the pathogen. Bacterial flagella are made from filaments of proteins, and some flagella are also enclosed by a sheath that is similar to the outer membrane that encloses certain bacteria. The function of this sheath is unclear, although some researchers have suggested that it might prevent the immune system from detecting the proteins in the flagellum. Now, by studying the interactions between the Hawaiian bobtail squid and a marine bacterium, Brennan et al. show that the sheath can actually alert the host that the bacteria are around. The Hawaiian bobtail squid collects bioluminescent bacteria within a so-called ‘light organ’. This organ undergoes a number of developmental changes to house the bacteria, and the squid then uses the light from the bacteria to mask its own shadow, which helps it to avoid being detected by predators. Brennan et al. compared how wild-type bacteria and mutant bacteria that either had no flagella, or had flagella that did not rotate, interacted with young squid. Only bacteria with working flagella were able to trigger the normal development of the squid’s light organ, which suggests that the rotating flagella are releasing the signal that tells the squid that the beneficial bacteria are present. Brennan et al. demonstrated that the rotation of sheathed flagella led to the release of a molecule called lipopolysaccharide. This molecule is known to activate the immune system in animals, and it is one of the bacterial signals that the squid responds to. Moreover, when the flagella of other bacteria with sheaths—such as those that cause cholera—are rotating, there is also an increase in the release of lipopolysaccharide. However, rotation of the flagella of bacteria without sheaths has no such effect. The next challenge will be to test the importance of this release of lipopolysaccharide from rotating flagella on the outcome of bacterial diseases of humans and other animals. DOI:http://dx.doi.org/10.7554/eLife.01579.002
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Affiliation(s)
- Caitlin A Brennan
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, United States
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Norsworthy AN, Visick KL. Gimme shelter: how Vibrio fischeri successfully navigates an animal's multiple environments. Front Microbiol 2013; 4:356. [PMID: 24348467 PMCID: PMC3843225 DOI: 10.3389/fmicb.2013.00356] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/09/2013] [Indexed: 12/19/2022] Open
Abstract
Bacteria successfully colonize distinct niches because they can sense and appropriately respond to a variety of environmental signals. Of particular interest is how a bacterium negotiates the multiple, complex environments posed during successful infection of an animal host. One tractable model system to study how a bacterium manages a host’s multiple environments is the symbiotic relationship between the marine bacterium, Vibrio fischeri, and its squid host, Euprymna scolopes. V. fischeri encounters many different host surroundings ranging from initial contact with the squid to ultimate colonization of a specialized organ known as the light organ. For example, upon recognition of the squid, V. fischeri forms a biofilm aggregate outside the light organ that is required for efficient colonization. The bacteria then disperse from this biofilm to enter the organ, where they are exposed to nitric oxide, a molecule that can act as both a signal and an antimicrobial. After successfully managing this potentially hostile environment, V. fischeri cells finally establish their niche in the deep crypts of the light organ where the bacteria bioluminesce in a pheromone-dependent fashion, a phenotype that E. scolopes utilizes for anti-predation purposes. The mechanism by which V. fischeri manages these environments to outcompete all other bacterial species for colonization of E. scolopes is an important and intriguing question that will permit valuable insights into how a bacterium successfully associates with a host. This review focuses on specific molecular pathways that allow V. fischeri to establish this exquisite bacteria–host interaction.
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Affiliation(s)
- Allison N Norsworthy
- Department of Microbiology and Immunology, Loyola University Medical Center Maywood, IL, USA
| | - Karen L Visick
- Department of Microbiology and Immunology, Loyola University Medical Center Maywood, IL, USA
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Contribution of six flagellin genes to the flagellum biogenesis of Vibrio vulnificus and in vivo invasion. Infect Immun 2013; 82:29-42. [PMID: 24101693 DOI: 10.1128/iai.00654-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Vibrio vulnificus is a halophilic pathogenic bacterium that is motile due to the presence of a single polar flagellum. V. vulnificus possesses a total of six flagellin genes organized into two loci (flaFBA and flaCDE). We proved that all six of the flagellin genes were transcribed, whereas only five (FlaA, -B, -C, -D, and -F) of the six flagellin proteins were detected. To understand roles of the six V. vulnificus flagellins in motility and virulence, mutants with single and multiple flagellin deletions were constructed. Mutations in flaB or flaC or the flaCDE locus resulted in a significant decrease in motility, adhesion, and cytotoxicity, whereas single mutations in the other flagellin genes or the flaFBA locus showed little or no effect. The motility was completely abolished only in the mutant lacking all six flagellin genes (flaFBA flaCDE). Surprisingly, a double mutation of flaB and flaD, a gene sharing 99% identity with the flaB at the amino acid level, resulted in the largest decrease in motility, adhesion, and cytotoxicity except for the mutant in which all six genes were deleted (the hexa mutant). Additionally, the 50% lethal doses (LD50s) of the flaB flaD and the flaFBA flaCDE mutants increased 23- and 91-fold in a mouse model, respectively, and the in vitro and in vivo invasiveness of the mutants was significantly decreased compared to that of the wild type. Taken together, the multiple flagellin subunits differentially contribute to the flagellum biogenesis and the pathogenesis of V. vulnificus, and among the six flagellin genes, flaB, flaD, and flaC were the most influential components.
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Verma SC, Miyashiro T. Quorum sensing in the squid-Vibrio symbiosis. Int J Mol Sci 2013; 14:16386-401. [PMID: 23965960 PMCID: PMC3759917 DOI: 10.3390/ijms140816386] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 07/24/2013] [Accepted: 07/26/2013] [Indexed: 02/08/2023] Open
Abstract
Quorum sensing is an intercellular form of communication that bacteria use to coordinate group behaviors such as biofilm formation and the production of antibiotics and virulence factors. The term quorum sensing was originally coined to describe the mechanism underlying the onset of luminescence production in cultures of the marine bacterium Vibrio fischeri. Luminescence and, more generally, quorum sensing are important for V. fischeri to form a mutualistic symbiosis with the Hawaiian bobtail squid, Euprymna scolopes. The symbiosis is established when V. fischeri cells migrate via flagella-based motility from the surrounding seawater into a specialized structure injuvenile squid called the light organ. The cells grow to high cell densities within the light organ where the infection persists over the lifetime of the animal. A hallmark of a successful symbiosis is the luminescence produced by V. fischeri that camouflages the squid at night by eliminating its shadow within the water column. While the regulatory networks governing quorum sensing are critical for properly regulating V. fischeri luminescence within the squid light organ, they also regulate luminescence-independent processes during symbiosis. In this review, we discuss the quorum-sensing network of V. fischeri and highlight its impact at various stages during host colonization.
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Affiliation(s)
- Subhash C Verma
- Department of Biochemistry and Molecular Biology, Eberly College of Science, the Pennsylvania State University, 219 Wartik Lab, University Park, PA 16802, USA.
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Brennan CA, Mandel MJ, Gyllborg MC, Thomasgard KA, Ruby EG. Genetic determinants of swimming motility in the squid light-organ symbiont Vibrio fischeri. Microbiologyopen 2013; 2:576-94. [PMID: 23907990 PMCID: PMC3948606 DOI: 10.1002/mbo3.96] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 04/19/2013] [Accepted: 05/06/2013] [Indexed: 01/07/2023] Open
Abstract
Bacterial flagellar motility is a complex cellular behavior required for the colonization of the light-emitting organ of the Hawaiian bobtail squid, Euprymna scolopes, by the beneficial bioluminescent symbiont Vibrio fischeri. We characterized the basis of this behavior by performing (i) a forward genetic screen to identify mutants defective in soft-agar motility, as well as (ii) a transcriptional analysis to determine the genes that are expressed downstream of the flagellar master regulator FlrA. Mutants with severe defects in soft-agar motility were identified due to insertions in genes with putative roles in flagellar motility and in genes that were unexpected, including those predicted to encode hypothetical proteins and cell division-related proteins. Analysis of mutants for their ability to enter into a productive symbiosis indicated that flagellar motility mutants are deficient, while chemotaxis mutants are able to colonize a subset of juvenile squid to light-producing levels. Thirty-three genes required for normal motility in soft agar were also downregulated in the absence of FlrA, suggesting they belong to the flagellar regulon of V. fischeri. Mutagenesis of putative paralogs of the flagellar motility genes motA, motB, and fliL revealed that motA1, motB1, and both fliL1 and fliL2, but not motA2 and motB2, likely contribute to soft-agar motility. Using these complementary approaches, we have characterized the genetic basis of flagellar motility in V. fischeri and furthered our understanding of the roles of flagellar motility and chemotaxis in colonization of the juvenile squid, including identifying 11 novel mutants unable to enter into a productive light-organ symbiosis.
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Affiliation(s)
- Caitlin A Brennan
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin
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Metatranscriptomics reveal differences in in situ energy and nitrogen metabolism among hydrothermal vent snail symbionts. ISME JOURNAL 2013; 7:1556-67. [PMID: 23619306 PMCID: PMC3721115 DOI: 10.1038/ismej.2013.45] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/31/2013] [Accepted: 02/11/2013] [Indexed: 01/04/2023]
Abstract
Despite the ubiquity of chemoautotrophic symbioses at hydrothermal vents, our understanding of the influence of environmental chemistry on symbiont metabolism is limited. Transcriptomic analyses are useful for linking physiological poise to environmental conditions, but recovering samples from the deep sea is challenging, as the long recovery times can change expression profiles before preservation. Here, we present a novel, in situ RNA sampling and preservation device, which we used to compare the symbiont metatranscriptomes associated with Alviniconcha, a genus of vent snail, in which specific host-symbiont combinations are predictably distributed across a regional geochemical gradient. Metatranscriptomes of these symbionts reveal key differences in energy and nitrogen metabolism relating to both environmental chemistry (that is, the relative expression of genes) and symbiont phylogeny (that is, the specific pathways employed). Unexpectedly, dramatic differences in expression of transposases and flagellar genes suggest that different symbiont types may also have distinct life histories. These data further our understanding of these symbionts' metabolic capabilities and their expression in situ, and suggest an important role for symbionts in mediating their hosts' interaction with regional-scale differences in geochemistry.
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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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Liang H, Wu Z, Jian J, Liu Z. Construction of a fusion flagellin complex and evaluation of the protective immunity of it in red snapper (Lutjanus sanguineus). Lett Appl Microbiol 2012; 55:115-21. [DOI: 10.1111/j.1472-765x.2012.03267.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Chavez-Dozal A, Hogan D, Gorman C, Quintanal-Villalonga A, Nishiguchi MK. Multiple Vibrio fischeri genes are involved in biofilm formation and host colonization. FEMS Microbiol Ecol 2012; 81:562-73. [PMID: 22486781 DOI: 10.1111/j.1574-6941.2012.01386.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 03/30/2012] [Accepted: 04/02/2012] [Indexed: 02/03/2023] Open
Abstract
Biofilms are increasingly recognized as being the predominant form for survival for most bacteria in the environment. The successful colonization of Vibrio fischeri in its squid host Euprymna tasmanica involves complex microbe-host interactions mediated by specific genes that are essential for biofilm formation and colonization. Here, structural and regulatory genes were selected to study their role in biofilm formation and host colonization. We have mutated several genes (pilT, pilU, flgF, motY, ibpA and mifB) by an insertional inactivation strategy. The results demonstrate that structural genes responsible for synthesis of type IV pili and flagella are crucial for biofilm formation and host infection. Moreover, regulatory genes affect colony aggregation by various mechanisms, including alteration of synthesis of transcriptional factors and regulation of extracellular polysaccharide production. These results reflect the significance of how genetic alterations influence communal behavior, which is important in understanding symbiotic relationships.
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Affiliation(s)
- Alba Chavez-Dozal
- Department of Biology, New Mexico State University, Las Cruces, NM 88003-8001, USA
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Squid-derived chitin oligosaccharides are a chemotactic signal during colonization by Vibrio fischeri. Appl Environ Microbiol 2012; 78:4620-6. [PMID: 22522684 DOI: 10.1128/aem.00377-12] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Chitin, a polymer of N-acetylglucosamine (GlcNAc), is noted as the second most abundant biopolymer in nature. Chitin serves many functions for marine bacteria in the family Vibrionaceae ("vibrios"), in some instances providing a physical attachment site, inducing natural genetic competence, and serving as an attractant for chemotaxis. The marine luminous bacterium Vibrio fischeri is the specific symbiont in the light-emitting organ of the Hawaiian bobtail squid, Euprymna scolopes. The bacterium provides the squid with luminescence that the animal uses in an antipredatory defense, while the squid supports the symbiont's nutritional requirements. V. fischeri cells are harvested from seawater during each host generation, and V. fischeri is the only species that can complete this process in nature. Furthermore, chitin is located in squid hemocytes and plays a nutritional role in the symbiosis. We demonstrate here that chitin oligosaccharides produced by the squid host serve as a chemotactic signal for colonizing bacteria. V. fischeri uses the gradient of host chitin to enter the squid light organ duct and colonize the animal. We provide evidence that chitin serves a novel function in an animal-bacterial mutualism, as an animal-produced bacterium-attracting synomone.
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