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Dingjiang Liu - One of the best experts on this subject based on the ideXlab platform.

Wayne A Hendrickson - One of the best experts on this subject based on the ideXlab platform.

  • crystal structures of apparent saccharide sensors from Histidine Kinase receptors prevalent in a human gut symbiont
    FEBS Journal, 2014
    Co-Authors: Zhen Zhang, Wayne A Hendrickson, Qun Liu
    Abstract:

    The adult human gut is a complicated ecosystem in which host–bacterium symbiosis plays an important role. Bacteroides thetaiotaomicron is a predominant member of the gut microflora, providing the human digestive tract with a large number of glycolytic enzymes. Expression of many of these enzymes appears to be controlled by Histidine Kinase receptors that are fused into unusual hybrid two-component systems that share homologous periplasmic sensor domains. These sensor domains belong to the third most populated (HK3) family based on a previous unpublished bioinformatics analysis of predicted Histidine Kinase sensors. Here, we present the crystal structures of two sensor domains representative of the HK3 family. Each sensor is folded into three domains: two-seven-bladed β-propeller domains and one β-sandwich domain. Both sensors form dimers in crystals, and one sensor appears to be physiologically relevant. The folding characteristics in the individual domains, the domain organization, and the oligomeric architecture are all unique to HK3 sensors. Sequence analysis of the HK3 sensors indicates that these sensor domains are shared among other signaling molecules, implying combinatorial molecular evolution. Database The structural data for the crystallographic results for HK3 BT4673S and HK3 BT3049S have been deposited in the Protein Data Bank under accession numbers 3OTT and 3V9F, respectively. Structured digital abstract HK3BT3049S and HK3BT3049S bind by x-ray crystallography (View interaction) HK3BT3049S and HK3BT3049S bind by molecular sieving (View interaction) HK3BT3049S and HK3BT3049S bind by cosedimentation through density gradient (View interaction) HK3BT4673s and HK3BT4673s bind by cosedimentation through density gradient (View interaction) HK3BT4673s and HK3BT4673s bind by molecular sieving (View interaction)

  • an asymmetry to symmetry switch in signal transmission by the Histidine Kinase receptor for tmao
    Structure, 2012
    Co-Authors: Jason O Moore, Wayne A Hendrickson
    Abstract:

    Summary The osmoregulator trimethylamine-N-oxide (TMAO), commonplace in aquatic organisms, is used as the terminal electron acceptor for respiration in many bacterial species. The TMAO reductase (Tor) pathway for respiratory catalysis is controlled by a receptor system that comprises the TMAO-binding protein TorT, the sensor Histidine Kinase TorS, and the response regulator TorR. Here we study the TorS/TorT sensor system to gain mechanistic insight into signaling by Histidine Kinase receptors. We determined crystal structures for complexes of TorS sensor domains with apo TorT and with TorT (TMAO); we characterized TorS sensor associations with TorT in solution; we analyzed the thermodynamics of TMAO binding to TorT-TorS complexes; and we analyzed in vivo responses to TMAO through the TorT/TorS/TorR system to test structure-inspired hypotheses. TorS-TorT(apo) is an asymmetric 2:2 complex that binds TMAO with negative cooperativity to form a symmetric active Kinase.

  • structural characterization of the predominant family of Histidine Kinase sensor domains
    Journal of Molecular Biology, 2010
    Co-Authors: Zhen Zhang, Wayne A Hendrickson
    Abstract:

    Histidine Kinase (HK) receptors are used ubiquitously by bacteria to monitor environmental changes, and they are also prevalent in plants, fungi, and other protists. Typical HK receptors have an extracellular sensor portion that detects a signal, usually a chemical ligand, and an intracellular transmitter portion that includes both the Kinase domain itself and the site for Histidine phosphorylation. While Kinase domains are highly conserved, sensor domains are diverse. HK receptors function as dimers, but the molecular mechanism for signal transduction across cell membranes remains obscure. In this study, eight crystal structures were determined from five sensor domains representative of the most populated family, family HK1, found in a bioinformatic analysis of predicted sensor domains from transmembrane HKs. Each structure contains an inserted repeat of PhoQ/DcuS/CitA (PDC) domains, and similarity between sequence and structure is correlated across these and other double-PDC sensor proteins. Three of the five sensors crystallize as dimers that appear to be physiologically relevant, and comparisons between ligated structures and apo-state structures provide insights into signal transmission. Some HK1 family proteins prove to be sensors for chemotaxis proteins or diguanylate cyclase receptors, implying a combinatorial molecular evolution.

  • structural analysis of sensor domains from the tmao responsive Histidine Kinase receptor tors
    Structure, 2009
    Co-Authors: Jason O Moore, Wayne A Hendrickson
    Abstract:

    Histidine Kinase receptors respond to diverse signals and mediate signal transduction across the plasma membrane in all prokaryotes and certain eukaryotes. Each receptor is part of a two-component system that regulates a particular cellular process. Organisms that use trimethylamine-N-oxide (TMAO) as a terminal electron acceptor typically control their anaerobic respiration through the TMAO reductase (Tor) pathway, which the TorS Histidine Kinase activates when sensing TMAO in the environment. We have determined crystal structures for the periplasmic sensor domains of TorS receptors from Escherichia coli and Vibrio parahaemolyticus. TorS sensor domains have a novel fold consisting of a membrane-proximal right-handed four-helical bundle and a membrane-distal left-handed four-helical bundle, but conformational dispositions differ significantly in the two structures. Isolated TorS sensor domains dimerize in solution; and from comparisons with dimeric NarX and Tar sensors, we postulate that signaling through TorS dimers involves a piston-type displacement between helices.

  • structural analysis of ligand stimulation of the Histidine Kinase narx
    Structure, 2009
    Co-Authors: J Cheung, Wayne A Hendrickson
    Abstract:

    Histidine Kinase receptors are a large family of membrane-spanning proteins found in many prokaryotes and some eukaryotes. They are a part of two-component signal transduction systems, which each comprise a sensor Kinase and a response regulator and are involved with the regulation of many cellular processes. NarX is a Histidine Kinase receptor that responds to nitrate and nitrite to effect regulation of anaerobic respiration in various bacteria. We present high-resolution X-ray crystal structures of the periplasmic sensor domain from Escherichia coli NarX in a complex with nitrate and in the apo state. Our analysis reveals that nitrate-binding induces conformation changes that result in a piston-type displacement between the N- and C-terminal helices of the periplasmic domain. Such conformational changes might represent a conserved mechanism of signaling in Histidine Kinases by which ligand binding is communicated across the lipid bilayer.

Rieko Ishima - One of the best experts on this subject based on the ideXlab platform.

Mark J Mandel - One of the best experts on this subject based on the ideXlab platform.

  • hybrid Histidine Kinase bink represses vibrio fischeri biofilm signaling at multiple developmental stages
    Journal of Bacteriology, 2021
    Co-Authors: Katherine M Bultman, Denise A Ludvik, Mark J Mandel
    Abstract:

    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 symbiosis polysaccharide Syp. TCS systems are broadly important for bacteria to sense environmental cues and then direct changes in behavior. Previously, we identified the 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.

  • hybrid Histidine Kinase bink represses vibrio fischeri biofilm signaling at multiple developmental stages
    bioRxiv, 2021
    Co-Authors: Denise A Ludvik, Katherine M Bultman, Mark J Mandel
    Abstract:

    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 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.

  • the Histidine Kinase bink is a negative regulator of biofilm formation and squid colonization
    Journal of Bacteriology, 2016
    Co-Authors: John F Brooks, Mark J Mandel
    Abstract:

    Bacterial colonization of animal epithelial tissue is a dynamic process that relies on precise molecular communication. Colonization of Euprymna scolopes bobtail squid by Vibrio fischeri bacteria requires bacterial aggregation in host mucus as the symbiont transitions from a planktonic lifestyle in seawater to biofilm-associated in the host. We have identified a gene, binK (biofilm inhibitor Kinase; VF_A0360), which encodes an orphan hybrid Histidine Kinase that negatively regulates the V. fischeri symbiotic biofilm (Syp) in vivo and in vitro . We identified binK mutants as exhibiting a colonization advantage in a global genetic screen, a phenotype that we confirmed in controlled competition experiments. Bacterial biofilm aggregates in the host are larger in strains lacking BinK, whereas overexpression of BinK suppresses biofilm formation and squid colonization. Signaling through BinK is required for temperature modulation of biofilm formation at 28°C. Furthermore, we present evidence that BinK acts upstream of SypG, the σ 54 -dependent transcriptional regulator of the syp biofilm locus. The BinK effects are dependent on intact signaling in the RscS-Syp biofilm pathway. Therefore, we propose that BinK antagonizes the signal from RscS and serves as an integral component in V. fischeri biofilm regulation. IMPORTANCE Bacterial lifestyle transitions underlie the colonization of animal hosts from environmental reservoirs. Formation of matrix-enclosed, surface-associated aggregates (biofilms) are common in beneficial and pathogenic associations, but investigating the genetic basis of biofilm development in live animal hosts remains a significant challenge. Using the bobtail squid light organ as a model, we analyzed putative colonization factors and identified a Histidine Kinase that negatively regulates biofilm formation at the host interface. This work reveals a novel in vivo biofilm regulator that influences the transition of bacteria from their planktonic state in seawater to becoming tight aggregates of cells in the host. The study enriches our understanding of biofilm regulation and beneficial colonization by an animal9s microbiota.

Chieri Tomomori - One of the best experts on this subject based on the ideXlab platform.