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Bacterial signal transduction

Alexander Simonis, Alexandra Schubert-Unkmeir
Acid sphingomyelinase (ASM) is a key enzyme in sphingolipid metabolism that converts sphingomyelin to ceramide, thereby modulating membrane structures and signal transduction. Bacterial pathogens can manipulate ASM activity and function, and use host sphingolipids during multiple steps of their infection process. An increase in ceramides upon infection results in the formation of ceramide-enriched membrane platforms that serve to cluster receptor molecules and organize intracellular signaling molecules, thus facilitating bacterial uptake...
June 1, 2018: Biological Chemistry
Marie I Samanovic, Hao-Chi Hsu, Marcus B Jones, Victoria Jones, Michael R McNeil, Samuel H Becker, Ashley T Jordan, Miroslav Strnad, Changcheng Xu, Mary Jackson, Huilin Li, K Heran Darwin
It was recently reported that the human-exclusive pathogen Mycobacterium tuberculosis secretes cytokinins, which had only been known as plant hormones. While cytokinins are well-established, adenine-based signaling molecules in plants, they have never been shown to participate in signal transduction in other kingdoms of life. M. tuberculosis is not known to interact with plants. Therefore, we tested the hypothesis that cytokinins trigger transcriptional changes within this bacterial species. Here, we show cytokinins induced the strong expression of the M...
June 19, 2018: MBio
Tadashi Watanabe, Atsuko Sugimoto, Kohei Hosokawa, Masahiro Fujimuro
Signal transduction pathways play a key role in the regulation of cell growth, cell differentiation, cell survival, apoptosis, and immune responses. Bacterial and viral pathogens utilize the cell signal pathways by encoding their own proteins or noncoding RNAs to serve their survival and replication in infected cells. Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), is classified as a rhadinovirus in the γ-herpesvirus subfamily and was the eighth human herpesvirus to be discovered from Kaposi's sarcoma specimens...
2018: Advances in Experimental Medicine and Biology
Dylan W White, Sarah R Elliott, Evan Odean, Lynne T Bemis, Anna D Tischler
Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator of vesiculogenesis. Here, we present data supporting a role for the M. tuberculosis Pst/SenX3-RegX3 signal transduction system in regulating MV production. Deletion of pstA1 , which encodes a transmembrane component of the phosphate-specific transport (Pst) system, causes constitutive activation of the SenX3-RegX3 two-component system, leading to increased protein secretion via the specialized ESX-5 type VII secretion system...
June 12, 2018: MBio
Geoffrey Gourinchas, Udo Heintz, Andreas Winkler
Organisms adapt to environmental cues using diverse signaling networks. In order to sense and integrate light for regulating various biological functions, photoreceptor proteins have evolved in a modular way. This modularity is targeted in the development of optogenetic tools enabling the control of cellular events with high spatiotemporal precision. However, the limited understanding of signaling mechanisms impedes the rational design of innovative photoreceptor-effector couples. Here we reveal molecular details of signal transduction in phytochrome-regulated diguanylyl-cyclases...
June 5, 2018: ELife
Carolina López, Susana K Checa, Fernando C Soncini
Periplasmic thiol/disulfide oxidoreductases participate in the formation and isomerization of disulphide bonds and contribute to the virulence of pathogenic microorganisms. Among the systems encoded in the Salmonella genome, the scsABCD locus was shown to be required to cope with Cu and H2 O2 stress. Here we report that this locus forms an operon whose transcription is driven by a promoter upstream of scsA and depends on CpxR/CpxA and on Cu. Furthermore, genes homologues to scsB , scsC and scsD are always detected immediately downstream scsA and in the same genetic arrangement in all scsA -harboring enterobacterial species...
June 4, 2018: Journal of Bacteriology
Zhen Zhang, Ronglian Xing, Zhimeng Lv, Yina Shao, Weiwei Zhang, Xuelin Zhao, Chenghua Li
Accumulative evidence has supported the pivotal roles of gut microbiota in shaping host health in a wide range of animals. However, the relationship between gut microbiota and sea cucumber disease is poorly understood. Using the Illumina sequencing of bacterial 16 S rRNA gene, we investigated the divergence of gut bacterial communities between healthy and skin ulceration syndrome (SUS) diseased Apostichopus japonicus. The results showed that bacterial phylotypes in both groups were closely related at phylum level with predominant component of Proteobacteria (>90%)...
June 1, 2018: Fish & Shellfish Immunology
Sergey A Shmakov, Kira S Makarova, Yuri I Wolf, Konstantin V Severinov, Eugene V Koonin
The CRISPR-Cas systems of bacterial and archaeal adaptive immunity consist of direct repeat arrays separated by unique spacers and multiple CRISPR-associated ( cas ) genes encoding proteins that mediate all stages of the CRISPR response. In addition to the relatively small set of core cas genes that are typically present in all CRISPR-Cas systems of a given (sub)type and are essential for the defense function, numerous genes occur in CRISPR- cas loci only sporadically. Some of these have been shown to perform various ancillary roles in CRISPR response, but the functional relevance of most remains unknown...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
Mukesh K Yadav, Jorge E Vidal, Yoon Y Go, Shin H Kim, Sung-Won Chae, Jae-Jun Song
Objective: Streptococcus pneumoniae colonizes the nasopharynx of children, and from nasopharynx it could migrate to the middle ear and causes acute otitis media (AOM). During colonization and AOM, the pneumococcus forms biofilms. In vitro biofilm formation requires a functional LuxS/AI-2 quorum-sensing system. We investigated the role of LuxS/AI-2 signaling in pneumococcal middle ear infection, and identified the genes that are regulated by LuxS/AI-2 during pneumococcal biofilm formation. Methods: Streptococcus pneumoniae D39 wild-type and an isogenic D39Δ luxS strain were utilized to evaluate in vitro biofilm formation, and in vivo colonization and epithelial damage using a microtiter plate assay and a rat model of pneumococcal middle ear infection, respectively...
2018: Frontiers in Cellular and Infection Microbiology
Philipp A M Schmidpeter, Xiaolong Gao, Vikrant Uphadyay, Jan Rheinberger, Crina M Nimigean
Cyclic nucleotide-modulated ion channels play several essential physiological roles. They are involved in signal transduction in photoreceptors and olfactory sensory neurons as well as pacemaking activity in the heart and brain. Investigations of the molecular mechanism of their actions, including structural and electrophysiological characterization, are restricted by the availability of stable, purified protein obtained from accessible systems. Here, we establish that SthK, a cyclic nucleotide-gated (CNG) channel from Spirochaeta thermophila , is an excellent model for investigating the gating of eukaryotic CNG channels at the molecular level...
May 11, 2018: Journal of General Physiology
Madison Zuverink, Joseph T Barbieri
Subsets of protein toxins utilize gangliosides as host receptors. Gangliosides are preferred receptors due to their extracellular localization on the eukaryotic cell and due to their essential nature in host physiology. Glycosphingolipids, including gangliosides, are mediators of signal transduction within and between eukaryotic cells. Protein toxins possess AB structure-function organization, where the A domain encodes a catalytic function for the posttranslational modification of a host macromolecule, including proteins and nucleic acids, and a B domain, which encodes host receptor recognition, including proteins and glycosphingolipids, alone or in combination...
2018: Progress in Molecular Biology and Translational Science
Jean-Pierre Changeux
The concept of allosteric interaction was initially proposed to account for the inhibitory feedback mechanism mediated by bacterial regulatory enzymes. In contrast with the classical mechanism of competitive, steric, interaction between ligands for a common site, allosteric interactions take place between topographically distinct sites and are mediated by a discrete and reversible conformational change of the protein. The concept was soon extended to membrane receptors for neurotransmitters and shown to apply to the signal transduction process which, in the case of the acetylcholine nicotinic receptor (nAChR), links the ACh binding site to the ion channel...
June 19, 2018: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Yun-Chu Chen, Eric C Holmes, Jakub Rajniak, Jung-Gun Kim, Sandy Tang, Curt R Fischer, Mary Beth Mudgett, Elizabeth S Sattely
Systemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity and complexity of defense signals that are required to initiate SAR signaling is not well understood. In this paper, we describe a metabolite, N -hydroxy-pipecolic acid ( N -OH-Pip) and provide evidence that this mobile molecule plays a role in initiating SAR signal transduction in Arabidopsis thaliana We demonstrate that FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), a key regulator of SAR-associated defense priming, can synthesize N -OH-Pip from pipecolic acid in planta , and exogenously applied N -OH-Pip moves systemically in Arabidopsis and can rescue the SAR-deficiency of fmo1 mutants...
May 7, 2018: Proceedings of the National Academy of Sciences of the United States of America
Raphael D Teixeira, Cristiane R Guzzo, Santiago Justo Arévalo, Maxuel O Andrade, Josielle Abrahão, Robson F de Souza, Chuck S Farah
The second messenger cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of bacterial lifestyle, controlling several behaviors, including the switch between sessile and motile states. C-di-GMP levels are controlled by the interplay between diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), which synthesize and hydrolyze this second messenger, respectively. These enzymes often contain additional domains that regulate activity via binding of small molecules, covalent modification or protein-protein interactions...
May 4, 2018: Journal of Biological Chemistry
Qirong Xiong, Chun Yee Lim, Jinghua Ren, Jiajing Zhou, Kanyi Pu, Mary B Chan-Park, Hui Mao, Yee Cheong Lam, Hongwei Duan
Microfluidic biochips hold great potential for liquid analysis in biomedical research and clinical diagnosis. However, the lack of integrated on-chip liquid mixing, bioseparation and signal transduction presents a major challenge in achieving rapid, ultrasensitive bioanalysis in simple microfluidic configurations. Here we report magnetic nanochain integrated microfluidic chip built upon the synergistic functions of the nanochains as nanoscale stir bars for rapid liquid mixing and as capturing agents for specific bioseparation...
May 1, 2018: Nature Communications
Fabio Gervasi, Patrizia Ferrante, Maria Teresa Dettori, Marco Scortichini, Ignazio Verde
Bacterial spot caused by Xanthomonas arboricola pv. pruni (Xap) is a major threat to Prunus species worldwide. The molecular mechanisms of peach resistance to Xap during early leaf infection were investigated by RNA-Seq analysis of two Prunus persica cultivars, 'Redkist' (resistant), and 'JH Hale' (susceptible) at 30 minutes, 1 and 3 hours-post-infection (hpi). Both cultivars exhibited extensive modulation of gene expression at 30 mpi, which reduced significantly at 1 hpi, increasing again at 3 hpi. Overall, 714 differentially expressed genes (DEGs) were detected in 'Redkist' (12% at 30 mpi and 1 hpi and 88% at 3 hpi)...
2018: PloS One
Neeraj K Lal, Ugrappa Nagalakshmi, Nicholas K Hurlburt, Rosalva Flores, Aurelie Bak, Pyae Sone, Xiyu Ma, Gaoyuan Song, Justin Walley, Libo Shan, Ping He, Clare Casteel, Andrew J Fisher, Savithramma P Dinesh-Kumar
Plants employ cell-surface pattern recognition receptors (PRRs) to detect pathogens. Although phytohormones produced during PRR signaling play an essential role in innate immunity, a direct link between PRR activation and hormone regulation is unknown. EFR is a PRR that recognizes bacterial EF-Tu and activates immune signaling. Here we report that EFR regulates the phytohormone jasmonic acid (JA) through direct phosphorylation of a receptor-like cytoplasmic kinase, BIK1. The BIK1 structure revealed that the EFR-phosphorylated sites reside on a uniquely extended loop away from the BIK1 kinase core domain...
April 11, 2018: Cell Host & Microbe
Heikki Takala, Heli K Lehtivuori, Oskar Berntsson, Ashley Hughes, Rahul Nanekar, Stephan Niebling, Matthijs Panman, Léocadie Henry, Andreas Menzel, Sebastian Westenhoff, Janne A Ihalainen
Phytochromes are photoreceptors in plants, fungi, and various microorganisms and cycle between metastable red light-absorbing (Pr) and far-red light-absorbing (Pfr) states. Their light responses are thought to follow a conserved structural mechanism that is triggered by isomerization of the chromophore. Downstream structural changes involve refolding of the so-called tongue extension of the phytochrome-specific GAF-related (PHY) domain of the photoreceptor. The tongue is connected to the chromophore by conserved DIP and PR X SF motifs and a conserved tyrosine, but the role of these residues in signal transduction is not clear...
May 25, 2018: Journal of Biological Chemistry
Adam James Waite, Nicholas W Frankel, Thierry Emonet
Living cells detect and process external signals using signaling pathways that are affected by random fluctuations. These variations cause the behavior of individual cells to fluctuate over time (behavioral variability) and generate phenotypic differences between genetically identical individuals (phenotypic diversity). These two noise sources reduce our ability to predict biological behavior because they diversify cellular responses to identical signals. Here, we review recent experimental and theoretical advances in understanding the mechanistic origin and functional consequences of such variation in Escherichia coli chemotaxis-a well-understood model of signal transduction and behavior...
May 20, 2018: Annual Review of Biophysics
Suyu Mei
Bacterial protein-protein interaction (PPI) networks are significant to reveal the machinery of signal transduction and drug resistance within bacterial cells. The database STRING has collected a large number of bacterial pathogen PPI networks, but most of the data are of low quality without being experimentally or computationally validated, thus restricting its further biomedical applications. We exploit the experimental data via four solutions to enhance the quality of M. tuberculosis H37Rv (MTB) PPI networks in STRING...
May 4, 2018: Journal of Proteome Research
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