scholarly journals Hybrid histidine kinase BinK represses Vibrio fischeri biofilm signaling at multiple developmental stages

2021 ◽  
Author(s):  
Denise A. Ludvik ◽  
Katherine M. Bultman ◽  
Mark J. Mandel
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Histidine Kinase ◽  
Biofilm Formation ◽  
Vibrio Fischeri ◽  
Bacterial Biofilm ◽  
Negative Regulator ◽  
Light Organ ◽  
Host Colonization ◽  
Hybrid Histidine Kinase

ABSTRACTThe symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and its exclusive light-organ symbiont, Vibrio fischeri, provides a natural system in which to study host-microbe specificity and gene regulation during the establishment of a mutually-beneficial symbiosis. Colonization of the host relies on bacterial biofilm-like aggregation in the squid mucus field. Symbiotic biofilm formation is controlled by a two-component signaling (TCS) system consisting of regulators RscS-SypF-SypG, which together direct transcription of the Syp symbiotic polysaccharide. TCS systems are broadly important for bacteria to sense environmental cues and then direct changes in behavior. Previously, we identified hybrid histidine kinase BinK as a strong negative regulator of V. fischeri biofilm regulation, and here we further explore the function of BinK. To inhibit biofilm formation, BinK requires the predicted phosphorylation sites in both the histidine kinase (H362) and receiver (D794) domains. Furthermore, we show that a strain lacking BinK yields RscS non-essential for host colonization, and imaging of aggregate size revealed no benefit to the presence of RscS in a background lacking BinK. Strains lacking RscS still suffered in competition, suggesting another function for the protein. Finally, we show that BinK functions to inhibit biofilm gene expression in the light organ crypts, providing evidence for biofilm gene regulation at later stages of host colonization. Overall, this study provides direct evidence for opposing activities of RscS and BinK and yields novel insights into biofilm regulation during the maturation of a beneficial symbiosis.IMPORTANCEBacteria are often in a biofilm state, and transitions between planktonic and biofilm lifestyles are important for pathogenic, beneficial, and environmental microbes. The critical nature of biofilm formation during Vibrio fischeri colonization of the Hawaiian bobtail squid light organ provides an opportunity to study development of this process in vivo using a combination of genetic and imaging approaches. The current work refines the signaling circuitry of the biofilm pathway in V. fischeri, provides evidence that biofilm regulatory changes occur in the host, and identifies BinK as one of the regulators of that process. This study provides information about how bacteria regulate biofilm gene expression in an intact animal host.

scholarly journals Hybrid histidine kinase BinK represses Vibrio fischeri biofilm signaling at multiple developmental stages

2021 ◽  
Author(s):  
Denise A. Ludvik ◽  
Katherine M. Bultman ◽  
Mark J. Mandel
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Histidine Kinase ◽  
Biofilm Formation ◽  
Vibrio Fischeri ◽  
Bacterial Biofilm ◽  
Negative Regulator ◽  
Light Organ ◽  
Host Colonization ◽  
Hybrid Histidine Kinase

The symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and its exclusive light-organ symbiont, Vibrio fischeri, provides a natural system in which to study host-microbe specificity and gene regulation during the establishment of a mutually-beneficial symbiosis. Colonization of the host relies on bacterial biofilm-like aggregation in the squid mucus field. Symbiotic biofilm formation is controlled by a two-component signaling (TCS) system consisting of regulators RscS-SypF-SypG, which together direct transcription of the Syp symbiotic polysaccharide. TCS systems are broadly important for bacteria to sense environmental cues and then direct changes in behavior. Previously, we identified hybrid histidine kinase BinK as a strong negative regulator of V. fischeri biofilm regulation, and here we further explore the function of BinK. To inhibit biofilm formation, BinK requires the predicted phosphorylation sites in both the histidine kinase (H362) and receiver (D794) domains. Furthermore, we show that RscS is not essential for host colonization when binK is deleted from strain ES114, and imaging of aggregate size revealed no benefit to the presence of RscS in a background lacking BinK. Strains lacking RscS still suffered in competition. Finally, we show that BinK functions to inhibit biofilm gene expression in the light organ crypts, providing evidence for biofilm gene regulation at later stages of host colonization. Overall, this study provides direct evidence for opposing activities of RscS and BinK and yields novel insights into biofilm regulation during the maturation of a beneficial symbiosis. IMPORTANCE Bacteria are often in a biofilm state, and transitions between planktonic and biofilm lifestyles are important for pathogenic, beneficial, and environmental microbes. The critical nature of biofilm formation during Vibrio fischeri colonization of the Hawaiian bobtail squid light organ provides an opportunity to study development of this process in vivo using a combination of genetic and imaging approaches. The current work refines the signaling circuitry of the biofilm pathway in V. fischeri, provides evidence that biofilm regulatory changes occur in the host, and identifies BinK as one of the regulators of that process. This study provides information about how bacteria regulate biofilm gene expression in an intact animal host.

scholarly journals The Histidine Kinase BinK Is a Negative Regulator of Biofilm Formation and Squid Colonization

2016 ◽  
Vol 198 (19) ◽  
pp. 2596-2607 ◽  
Author(s):  
John F. Brooks ◽  
Mark J. Mandel
Keyword(s):  
Histidine Kinase ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Negative Regulator ◽  
Epithelial Tissue ◽  
Temperature Modulation ◽  
Content Type ◽  
Animal Hosts ◽  
Biofilm Development

ABSTRACTBacterial colonization of animal epithelial tissue is a dynamic process that relies on precise molecular communication. Colonization ofEuprymna scolopesbobtail squid byVibrio fischeribacteria requires bacterial aggregation in host mucus as the symbiont transitions from a planktonic lifestyle in seawater to a biofilm-associated state in the host. We have identified a gene,binK(biofilm inhibitor kinase; VF_A0360), which encodes an orphan hybrid histidine kinase that negatively regulates theV. fischerisymbiotic biofilm (Syp)in vivoandin vitro. We identifiedbinKmutants as exhibiting a colonization advantage in a global genetic screen, a phenotype that we confirmed in controlled competition experiments. Bacterial biofilm aggregates in the host are larger in strains lacking BinK, whereas overexpression of BinK suppresses biofilm formation and squid colonization. Signaling through BinK is required for temperature modulation of biofilm formation at 28°C. Furthermore, we present evidence that BinK acts upstream of SypG, the σ54-dependent transcriptional regulator of thesypbiofilm locus. The BinK effects are dependent on intact signaling in the RscS-Syp biofilm pathway. Therefore, we propose that BinK antagonizes the signal from RscS and serves as an integral component inV. fischeribiofilm regulation.IMPORTANCEBacterial lifestyle transitions underlie the colonization of animal hosts from environmental reservoirs. Formation of matrix-enclosed, surface-associated aggregates (biofilms) is common in beneficial and pathogenic associations, but investigating the genetic basis of biofilm development in live animal hosts remains a significant challenge. Using the bobtail squid light organ as a model, we analyzed putative colonization factors and identified a histidine kinase that negatively regulates biofilm formation at the host interface. This work reveals a novelin vivobiofilm regulator that influences the transition of bacteria from their planktonic state in seawater to tight aggregates of cells in the host. The study enriches our understanding of biofilm regulation and beneficial colonization by an animal's microbiome.

scholarly journals The fimYZ Genes Regulate Salmonella enterica Serovar Typhimurium Invasion in Addition to Type 1 Fimbrial Expression and Bacterial Motility

2005 ◽  
Vol 73 (3) ◽  
pp. 1377-1385 ◽  
Author(s):  
M. Aaron Baxter ◽  
Bradley D. Jones
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Protein Interactions ◽  
Salmonella Enterica ◽  
Negative Regulator ◽  
Invasive Phenotype ◽  
Environmental Signals ◽  
Bacterial Physiology ◽  
Serovar Typhimurium

ABSTRACT An important step in Salmonella enterica serovar Typhimurium virulence is the ability to invade the intestinal epithelium. The invasion process requires a large number of genes encoded on Salmonella pathogenicity island 1 (SPI-1) at centisome 63 as well as genes located in other positions throughout the chromosome. Expression of the invasive phenotype is tightly regulated by environmental cues that are processed by a complex regulatory scheme. A central player in the invasion regulatory pathway is the HilA protein, which is transcriptional activator belonging to the OmpR/ToxR family. A number of positive regulators (hilC, hilD, fis, sirA/barA, csrAB, phoBR, fadD, envZ/ompR, and fliZ) and negative regulators (hha, hilE, lon, ams, phoP c and pag) have been identified that are able to alter expression of hilA transcription. Recent work has found that hilA transcription requires the HilD protein for activation. Other work has emphasized the importance of HilE as a negative regulator of hilA. Overexpression of hilE superrepresses hilA transcription, as well as the invasive phenotype. Two-hybrid experiments suggest that HilE exerts its regulatory influence on hilA through protein-protein interactions with HilD as the protein does not bind to the hilA promoter nor does it affect hilD transcription. As it seems likely that hilE plays an important role in translating environmental signals into invasion gene regulation, we have attempted to identify how the hilE gene itself is regulated. Our results indicate that the fimYZ genes, response regulatory proteins involved in type 1 fimbrial gene expression and recently implicated in motility gene regulation, are important activators of hilE expression. These findings indicate that invasion gene expression is coregulated with motility and adherence and provide experimental evidence that the expression of these virulence phenotypes is a subset of the overall regulation of bacterial physiology.

scholarly journals purL gene expression affects biofilm formation and symbiotic persistence of Photorhabdus temperata in the nematode Heterorhabditis bacteriophora

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2595-2603 ◽  
Author(s):  
Ruisheng An ◽  
Parwinder S. Grewal
Keyword(s):  
Gene Expression ◽  
Metabolic Pathway ◽  
Biofilm Formation ◽  
Heterorhabditis Bacteriophora ◽  
Bacterial Biofilm ◽  
Infective Juvenile ◽  
Plant Interactions ◽  
Symbiotic Interaction ◽  
The Impact ◽  
Photorhabdus Temperata

Extensive studies of the well-known legume and rhizobium symbiosis model system suggest that the purine metabolic pathway plays a key role in microbe–plant interactions, although the exact mechanism is unknown. Here, we report the impact of a key purine metabolic gene, purL, on the symbiotic interaction between the bacterium Photorhabdus temperata and its nematode partner Heterorhabditis bacteriophora. Real-time PCR assays showed that the purL gene was upregulated in P. temperata in the nematode infective juvenile compared with artificial media. Mutation of the purL gene by in-frame deletion dramatically decreased the capacity of the bacterium to persist in infective juveniles and its ability to form biofilm in vitro. It was further demonstrated that purL gene expression was positively related to bacterial biofilm formation and the symbiotic persistence of the bacterium in nematode infective juveniles. A ΔpurL mutant lost the ability to support infective juvenile formation in the media which weakly supported biofilm formation, suggesting that a critical level of biofilm formation is required by the bacteria to support infective juvenile formation and thus establish their partnership. In addition, the defects in both biofilm formation and symbiotic ability due to the disruption of the purL gene could be partially restored by the addition of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an intermediate of the purine biosynthesis pathway. Overall, these data indicate that the purine metabolic pathway is important in microbe–animal symbioses, and that it may influence symbiotic interactions at the level of biofilm formation.

scholarly journals Critical symbiont signals drive both local and systemic changes in diel and developmental host gene expression

2019 ◽  
Vol 116 (16) ◽  
pp. 7990-7999 ◽  
Author(s):  
Silvia Moriano-Gutierrez ◽  
Eric J. Koch ◽  
Hailey Bussan ◽  
Kymberleigh Romano ◽  
Mahdi Belcaid ◽  
...  
Keyword(s):  
Gene Expression ◽  
Visual Cues ◽  
Vibrio Fischeri ◽  
Single Mutation ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Transcriptional Responses ◽  
Transcriptional Signature ◽  
The Impact ◽  
Organ Colonization

The colonization of an animal’s tissues by its microbial partners creates networks of communication across the host’s body. We used the natural binary light-organ symbiosis between the squidEuprymna scolopesand its luminous bacterial partner,Vibrio fischeri, to define the impact of colonization on transcriptomic networks in the host. A night-active predator,E. scolopescoordinates the bioluminescence of its symbiont with visual cues from the environment to camouflage against moon and starlight. Like mammals, this symbiosis has a complex developmental program and a strong day/night rhythm. We determined how symbiont colonization impacted gene expression in the light organ itself, as well as in two anatomically remote organs: the eye and gill. While the overall transcriptional signature of light organ and gill were more alike, the impact of symbiosis was most pronounced and similar in light organ and eye, both in juvenile and adult animals. Furthermore, the presence of a symbiosis drove daily rhythms of transcription within all three organs. Finally, a single mutation inV. fischeri—specifically, deletion of theluxoperon, which abrogates symbiont luminescence—reduced the symbiosis-dependent transcriptome of the light organ by two-thirds. In addition, while the gills responded similarly to light-organ colonization by either the wild-type or mutant, luminescence was required for all of the colonization-associated transcriptional responses in the juvenile eye. This study defines not only the impact of symbiont colonization on the coordination of animal transcriptomes, but also provides insight into how such changes might impact the behavior and ecology of the host.

Differentially expressed genes reveal adaptations between free-living and symbiotic niches of Vibrio fischeri in a fully established mutualism

2006 ◽  
Vol 52 (12) ◽  
pp. 1218-1227 ◽  
Author(s):  
B W Jones ◽  
M K Nishiguchi
Keyword(s):  
Gene Expression ◽  
Host Specificity ◽  
Differentially Expressed Genes ◽  
Vibrio Fischeri ◽  
Differentially Expressed ◽  
Light Organ ◽  
Free Living ◽  
Expression Of Genes ◽  
Unique System ◽  
Insight Into

A major force driving in the innovation of mutualistic symbioses is the number of adaptations that both organisms must acquire to provide overall increased fitness for a successful partnership. Many of these symbioses are relatively dependent on the ability of the symbiont to locate a host (specificity), as well as provide some novel capability upon colonization. The mutualism between sepiolid squids and members of the Vibrionaceae is a unique system in which development of the symbiotic partnership has been studied in detail, but much remains unknown about the genetics of symbiont colonization and persistence within the host. Using a method that captures exclusively expressed transcripts in either free-living or host-associated strains of Vibrio fischeri, we identified and verified expression of genes differentially expressed in both states from two symbiotic strains of V. fischeri. These genes provide a glimpse into the microhabitat V. fischeri encounters in both free-living seawater and symbiotic host light organ-associated habitats, providing insight into the elements necessary for local adaptation and the evolution of host specificity in this unique mutualism.Key words: Vibrionaceae, gene expression, Sepiolidae, Euprymna, SCOTS.

Effects of inducer levels on a recombinant bacterial biofilm formation and gene expression

1994 ◽  
Vol 16 (9) ◽  
pp. 903-908 ◽  
Author(s):  
Ching-Tsan Huang ◽  
Steven W. Peretti ◽  
James D. Bryers
Keyword(s):  
Gene Expression ◽  
Biofilm Formation ◽  
Bacterial Biofilm
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