scholarly journals The noncoding small RNA SsrA is released by Vibrio fischeri and modulates critical host responses

PLoS Biology ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. e3000934 ◽  
Author(s):  
Silvia Moriano-Gutierrez ◽  
Clotilde Bongrand ◽  
Tara Essock-Burns ◽  
Leo Wu ◽  
Margaret J. McFall-Ngai ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Vibrio Fischeri ◽  
Membrane Vesicles ◽  
Antimicrobial Activities ◽  
Outer Membrane Vesicles ◽  
Host Responses ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Fitness Consequences ◽  
Animal Hosts

The regulatory noncoding small RNAs (sRNAs) of bacteria are key elements influencing gene expression; however, there has been little evidence that beneficial bacteria use these molecules to communicate with their animal hosts. We report here that the bacterial sRNA SsrA plays an essential role in the light-organ symbiosis between Vibrio fischeri and the squid Euprymna scolopes. The symbionts load SsrA into outer membrane vesicles, which are transported specifically into the epithelial cells surrounding the symbiont population in the light organ. Although an SsrA-deletion mutant (ΔssrA) colonized the host to a normal level after 24 h, it produced only 2/10 the luminescence per bacterium, and its persistence began to decline by 48 h. The host’s response to colonization by the ΔssrA strain was also abnormal: the epithelial cells underwent premature swelling, and host robustness was reduced. Most notably, when colonized by the ΔssrA strain, the light organ differentially up-regulated 10 genes, including several encoding heightened immune-function or antimicrobial activities. This study reveals the potential for a bacterial symbiont’s sRNAs not only to control its own activities but also to trigger critical responses promoting homeostasis in its host. In the absence of this communication, there are dramatic fitness consequences for both partners.

scholarly journals A New Niche for Vibrio logei, the Predominant Light Organ Symbiont of Squids in the GenusSepiola

1998 ◽  
Vol 180 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Pat M. Fidopiastis ◽  
Sigurd von Boletzky ◽  
Edward G. Ruby
Keyword(s):  
Coastal Waters ◽  
Vibrio Fischeri ◽  
Aliphatic Aldehyde ◽  
Mixed Population ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Light Organs ◽  
Luminous Bacteria ◽  
Animal Hosts ◽  
The Western Pacific

ABSTRACT Two genera of sepiolid squids—Euprymna, found primarily in shallow, coastal waters of Hawaii and the Western Pacific, and Sepiola, the deeper-, colder-water-dwelling Mediterranean and Atlantic squids—are known to recruit luminous bacteria into light organ symbioses. The light organ symbiont ofEuprymna spp. is Vibrio fischeri, but until now, the light organ symbionts of Sepiola spp. have remained inadequately identified. We used a combination of molecular and physiological characteristics to reveal that the light organs ofSepiola affinis and Sepiola robusta contain a mixed population of Vibrio logei and V. fischeri, with V. logei comprising between 63 and 100% of the bacteria in the light organs that we analyzed. V. logei had not previously been known to exist in such symbioses. In addition, this is the first report of two different species of luminous bacteria co-occurring within a single light organ. The luminescence of these symbiotic V. logei strains, as well as that of other isolates of V. logei tested, is reduced when they are grown at temperatures above 20°C, partly due to a limitation in the synthesis of aliphatic aldehyde, a substrate of the luminescence reaction. In contrast, the luminescence of the V. fischeri symbionts is optimal above 24°C and is not enhanced by aldehyde addition. Also, V. fischeri strains were markedly more successful than V. logei at colonizing the light organs of juvenile Euprymna scolopes, especially at 26°C. These findings have important implications for our understanding of the ecological dynamics and evolution of cooperative, and perhaps pathogenic, associations of Vibrio spp. with their animal hosts.

scholarly journals Vibrio fischeri lux Genes Play an Important Role in Colonization and Development of the Host Light Organ

2000 ◽  
Vol 182 (16) ◽  
pp. 4578-4586 ◽  
Author(s):  
Karen L. Visick ◽  
Jamie Foster ◽  
Judith Doino ◽  
Margaret McFall-Ngai ◽  
Edward G. Ruby
Keyword(s):  
Epithelial Cells ◽  
Light Emission ◽  
Vibrio Fischeri ◽  
Regulatory Proteins ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Light Emitting ◽  
Bioluminescent Bacterium ◽  
Lux Genes

ABSTRACT The bioluminescent bacterium Vibrio fischeri and juveniles of the squid Euprymna scolopes specifically recognize and respond to one another during the formation of a persistent colonization within the host's nascent light-emitting organ. The resulting fully developed light organ contains brightly luminescing bacteria and has undergone a bacterium-induced program of tissue differentiation, one component of which is a swelling of the epithelial cells that line the symbiont-containing crypts. While the luminescence (lux) genes of symbiotic V. fischeri have been shown to be highly induced within the crypts, the role of these genes in the initiation and persistence of the symbiosis has not been rigorously examined. We have constructed and examined three mutants (luxA, luxI, andluxR), defective in either luciferase enzymatic or regulatory proteins. All three are unable to induce normal luminescence levels in the host and, 2 days after initiating the association, had a three- to fourfold defect in the extent of colonization. Surprisingly, these lux mutants also were unable to induce swelling in the crypt epithelial cells. Complementing, in trans, the defect in light emission restored both normal colonization capability and induction of swelling. We hypothesize that a diminished level of oxygen consumption by a luciferase-deficient symbiotic population is responsible for the reduced fitness of lux mutants in the light organ crypts. This study is the first to show that the capacity for bioluminescence is critical for normal cell-cell interactions between a bacterium and its animal host and presents the first examples of V. fischeri genes that affect normal host tissue development.

scholarly journals Rotation of Vibrio fischeri Flagella Produces Outer Membrane Vesicles That Induce Host Development

2016 ◽  
Vol 198 (16) ◽  
pp. 2156-2165 ◽  
Author(s):  
Marie-Stephanie Aschtgen ◽  
Jonathan B. Lynch ◽  
Eric Koch ◽  
Julia Schwartzman ◽  
Margaret McFall-Ngai ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Pathogenic Bacteria ◽  
Vibrio Fischeri ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Surface Epithelium ◽  
Light Organ ◽  
Present Evidence ◽  
Content Type ◽  
Host Development

ABSTRACTUsing the squid-vibrio association, we aimed to characterize the mechanism through whichVibrio fischericells 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 byV. fischeriare 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. fischericells 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.IMPORTANCEDetermining 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 asVibrio,Helicobacter, andBrucellahas 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 ofV. fischericells 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.

scholarly journals Cyclodextrins reduce the ability of Pseudomonas aeruginosa outer-membrane vesicles to reduce CFTR Cl− secretion

2019 ◽  
Vol 316 (1) ◽  
pp. L206-L215 ◽  
Author(s):  
Roxanna Barnaby ◽  
Katja Koeppen ◽  
Bruce A. Stanton
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Epithelial Cells ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Airway Epithelial Cells ◽  
Outer Membrane Vesicles ◽  
Airway Epithelial ◽  
Ussing Chambers ◽  
Planktonic Growth ◽  
Apical Side

Pseudomonas aeruginosa secretes outer-membrane vesicles (OMVs) that fuse with cholesterol-rich lipid rafts in the apical membrane of airway epithelial cells and decrease wt-CFTR Cl− secretion. Herein, we tested the hypothesis that a reduction of the cholesterol content of CF human airway epithelial cells by cyclodextrins reduces the inhibitory effect of OMVs on VX-809 (lumacaftor)-stimulated Phe508del CFTR Cl− secretion. Primary CF bronchial epithelial cells and CFBE cells were treated with vehicle, hydroxypropyl-β-cyclodextrin (HPβCD), or methyl-β-cyclodextrin (MβCD), and the effects of OMVs secreted by P. aeruginosa on VX-809 stimulated Phe508del CFTR Cl− secretion were measured in Ussing chambers. Neither HPβCD nor MβCD were cytotoxic, and neither altered Phe508del CFTR Cl− secretion. Both cyclodextrins reduced OMV inhibition of VX-809-stimulated Phe508del-CFTR Cl− secretion when added to the apical side of CF monolayers. Both cyclodextrins also reduced the ability of P. aeruginosa to form biofilms and suppressed planktonic growth of P. aeruginosa. Our data suggest that HPβCD, which is in clinical trials for Niemann-Pick Type C disease, and MβCD, which has been approved by the U.S. Food and Drug Administration for use in solubilizing lipophilic drugs, may enhance the clinical efficacy of VX-809 in CF patients when added to the apical side of airway epithelial cells, and reduce planktonic growth and biofilm formation by P. aeruginosa. Both effects would be beneficial to CF patients.

scholarly journals An Expanded Transposon Mutant Library Reveals that Vibrio fischeri δ-Aminolevulinate Auxotrophs Can Colonize Euprymna scolopes

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Noreen L. Lyell ◽  
Alecia N. Septer ◽  
Anne K. Dunn ◽  
Drew Duckett ◽  
Julie L. Stoudenmire ◽  
...  
Keyword(s):  
Vibrio Fischeri ◽  
Light Organ ◽  
Mutant Library ◽  
Euprymna Scolopes ◽  
Simple Method ◽  
Content Type ◽  
Transposon Insertion ◽  
Rich Media ◽  
Show Evidence

ABSTRACT Libraries of defined mutants are valuable research tools but necessarily lack gene knockouts that are lethal under the conditions used in library construction. In this study, we augmented a Vibrio fischeri mutant library generated on a rich medium (LBS, which contains [per liter] 10 g of tryptone, 5 g of yeast extract, 20 g of NaCl, and 50 mM Tris [pH 7.5]) by selecting transposon insertion mutants on supplemented LBS and screening for those unable to grow on LBS. We isolated strains with insertions in alr, glr (murI), glmS, several heme biosynthesis genes, and ftsA, as well as a mutant disrupted 14 bp upstream of ftsQ. Mutants with insertions in ftsA or upstream of ftsQ were recovered by addition of Mg2+ to LBS, but their cell morphology and motility were affected. The ftsA mutant was more strongly affected and formed cells or chains of cells that appeared to wind back on themselves helically. Growth of mutants with insertions in glmS, alr, or glr was recovered with N-acetylglucosamine (NAG), d-alanine, or d-glutamate, respectively. We hypothesized that NAG, d-alanine, or d-glutamate might be available to V. fischeri in the Euprymna scolopes light organ; however, none of these mutants colonized the host effectively. In contrast, hemA and hemL mutants, which are auxotrophic for δ-aminolevulinate (ALA), colonized at wild-type levels, although mutants later in the heme biosynthetic pathway were severely impaired or unable to colonize. Our findings parallel observations that legume hosts provide Bradyrhizobium symbionts with ALA, but they contrast with virulence phenotypes of hemA mutants in some pathogens. The results further inform our understanding of the symbiotic light organ environment. IMPORTANCE By supplementing a rich yeast-based medium, we were able to recover V. fischeri mutants with insertions in conditionally essential genes, and further characterization of these mutants provided new insights into this bacterium's symbiotic environment. Most notably, we show evidence that the squid host can provide V. fischeri with enough ALA to support its growth in the light organ, paralleling the finding that legumes provide Bradyrhizobium ALA in symbiotic nodules. Taken together, our results show how a simple method of augmenting already rich media can expand the reach and utility of defined mutant libraries.

scholarly journals Genetic Analysis of Trimethylamine N-Oxide Reductases in the Light Organ Symbiont Vibrio fischeri ES114

2008 ◽  
Vol 190 (17) ◽  
pp. 5814-5823 ◽  
Author(s):  
Anne K. Dunn ◽  
Eric V. Stabb
Keyword(s):  
Vibrio Fischeri ◽  
Reductase Activity ◽  
Anaerobic Respiration ◽  
Gene Arrangement ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Light Organs ◽  
Dependent Growth ◽  
Tmao Reductase ◽  
Active Promoter

ABSTRACT Trimethylamine N-oxide (TMAO) reductases are widespread in bacteria and often function in anaerobic respiration. The regulation and expression of TMAO reductase operons have been well studied in model genera such as Escherichia, Shewanella, and Rhodobacter, although TMAO reductases are present in many other bacteria, including the marine Vibrio species. The genome sequence of Vibrio fischeri revealed three putative TMAO reductase operons, and a previous report identified TMAO reductase activity in symbiotic V. fischeri isolates associated with the light organs of adult Hawaiian bobtail squid, Euprymna scolopes. We examined the roles and regulation of these three operons using mutational analyses and promoter-reporter fusions. We found that the torECA promoter, and to a lesser extent the torYZ and dmsABC promoters, were active during symbiotic colonization of juvenile E. scolopes; however, a V. fischeri strain lacking TMAO reductase activity displays no discernible colonization defect over the first 48 h. Our studies also revealed that torECA has the most active promoter of the putative TMAO reductase operons, and TorECA is the major contributor to TMAO-dependent growth in V. fischeri under the conditions tested. Interestingly, the transcriptional regulation of TMAO reductase operons in V. fischeri appears to differ from that in previously studied organisms, such as Escherichia coli, which may reflect differences in gene arrangement and bacterial habitat. This study lays the foundation for using V. fischeri as a model system for studying TMAO reductases in the Vibrionaceae.

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