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Fangchao Song, Hao Wang, Karin Sauer, Dacheng Ren
Recently, we reported that the stiffness of poly(dimethylsiloxane) (PDMS) affects the attachment of Pseudomonas aeruginosa , and the morphology and antibiotic susceptibility of attached cells. To further understand how P. aeruginosa responses to material stiffness during attachment, the wild-type P. aeruginosa PAO1 and several isogenic mutants were characterized for their attachment on soft and stiff PDMS. Compared to the wild-type strain, mutation of the oprF gene abolished the differences in attachment, growth, and size of attached cells between soft and stiff PDMS surfaces...
2018: Frontiers in Microbiology
Anne E Mattingly, Nachiket Kamatkar, Bradley R Borlee, Joshua D Shrout
Pseudomonas aeruginosa exhibits flagellar-mediated swimming in liquid and swarming on hydrated surfaces under diverse nutrient conditions. Prior studies have implicated a phosphodiesterase, DipA, in regulating these flagella-mediated motilities, but collectively, the necessity for DipA was unclear. In this study, we find that the media composition conditionally constrains the influence of DipA on flagellar motility. We show that DipA exhibits more influence on minimal media supplemented with glutamate or glucose where flagellar motility was negated for the dipA mutant...
February 2, 2018: Applied and Environmental Microbiology
Serena Rinaldo, Giorgio Giardina, Federico Mantoni, Alessio Paone, Francesca Cutruzzolà
The nitrogen cycle pathways are responsible for the circulation of inorganic and organic N-containing molecules in nature. Among these pathways, those involving amino acids, N-oxides and in particular nitric oxide (NO) play strategic roles in the metabolism of microorganisms in natural environments and in host-pathogen interactions. Beyond their role in the N-cycle, amino acids and NO are also signalling molecules able to influence group behaviour in microorganisms and cell-cell communication in multicellular organisms, including humans...
February 1, 2018: FEMS Microbiology Letters
Xiaochen Yuan, Fang Tian, Chenyang He, Geoffrey B Severin, Christopher M Waters, Quan Zeng, Fengquan Liu, Ching-Hong Yang
Dickeya dadantii 3937 secretes pectate lyases (Pels) to degrade the plant cell wall. Previously, we have demonstrated that EGcpB and EcpC function as cyclic-di-GMP (c-di-GMP) specific phosphodiesterases (PDEs) to positively regulate Pel production. However, the diguanylate cyclase (DGC) responsible for the synthesis of c-di-GMP and dichotomously regulation of Pel has remained a mystery. Here, we identified GcpA is the dominant DGC to negatively regulate Pel production by specifically repressing pelD gene expression...
February 1, 2018: Molecular Plant Pathology
Candela Muriel, Eva Arrebola, Miguel Redondo-Nieto, Francisco Martínez-Granero, Blanca Jalvo, Sebastian Pfeilmeier, Esther Blanco-Romero, Irene Baena, Jacob G Malone, Rafael Rivilla, Marta Martín
The transcriptional regulator AmrZ is a global regulatory protein conserved within the pseudomonads. AmrZ can act both as a positive and a negative regulator of gene expression, controlling many genes implicated in environmental adaption. Regulated traits include motility, iron homeostasis, exopolysaccharides production and the ability to form biofilms. In Pseudomonas fluorescens F113, an amrZ mutant presents a pleiotropic phenotype, showing increased swimming motility, decreased biofilm formation and very limited ability for competitive colonization of rhizosphere, its natural habitat...
January 31, 2018: Scientific Reports
Yang Zhang, Jun Yang, Guangchun Bai
Clustered regularly interspaced short palindromic repeats (CRISPR) and the CRISPR-associated proteins (Cas) provide an adaptive immunity to bacteria and archaea against specific DNA invaders. Mycobacterium tuberculosis (Mtb) encodes a Type III CRISPR-Cas system, which has not been experimentally explored. In this study, we found that the CRISPR-Cas systems of both Mtb and M. bovis BCG were highly upregulated by deletion of Rv2837c (cnpB), which encodes a multifunctional protein that hydrolyzes cyclic di-AMP (c-di-AMP), cyclic di-GMP (c-di-GMP), and nanoRNAs (short oligonucleotides of five residues or shorter in length)...
January 29, 2018: Journal of Bacteriology
Jochen Schmid
The distinct biosynthesis pathways for microbial exopolysaccharide production provide different engineering strategies to tailor the chemical structures of the final polymers. This review focuses on the latest insights in the various pathways and identifies bottlenecks as well as promising targets for tailoring microbial polysaccharide production. The main engineering strategies includes the combinatorial assembly of glycosyltransferases and engineering of the Wzx and Wzy proteins for flipping of repeating units as well as polymerization...
January 17, 2018: Current Opinion in Biotechnology
Linlin Zhang, Yiwei Weng, Yu Wu, Xueying Wang, Zhe Yin, Huiying Yang, Wenhui Yang, Yiquan Zhang
Vibrio parahaemolyticus is capable of surviving in biofilm communities attached to biotic and abiotic surfaces. The exopolysaccharide (EPS) plays a key role in the maturing of the biofilm. The VPA1403-1412 (cpsA-J) operon is responsible for EPS production in V. parahaemolyticus. The expression of cpsA-J is controlled by ScrABC, intracellular concentration of c-di-GMP, CpsS-CpsR-CpsQ regulatory cascade, and quorum sensing. The data presented here showed that H-NS activates the EPS-dependent bacterial colony morphology and the transcription of cpsQ and cpsA-J...
January 20, 2018: Microbial Pathogenesis
Sinosh Skariyachan, Vaishnavi Sneha Sridhar, Swathi Packirisamy, Supreetha Toplar Kumargowda, Sneha Basavaraj Challapilli
Pseudomonas aeruginosa, a Gram-negative, rod-shaped bacterium causes widespread diseases in humans. This bacterium is frequently related to nosocomial infections such as pneumonia, urinary tract infections (UTIs) and bacteriaemia especially in immunocompromised patients. The current review focuses on the recent perspectives on biofilms formation by these bacteria. Biofilms are communities of microorganisms in which cells stick to each other and often adhere to a surface. These adherent cells are usually embedded within a self-produced matrix of extracellular polymeric substance (EPS)...
January 19, 2018: Folia Microbiologica
Kurt M Dahlstrom, Alan J Collins, Georgia Doing, Jaclyn N Taroni, Timothy J Gauvin, Casey S Greene, Deborah A Hogan, George A O'Toole
The Pseudomonas fluorescens genome encodes for 50+ proteins predicted to be involved in c-di-GMP signaling. Here, we demonstrate that when tested across 188 nutrients, these enzymes and effectors appear capable of impacting biofilm formation. Transcriptional analysis of network members across ∼50 nutrient conditions indicates that altered gene expression can explain a subset, but not all, of biofilm-formation responses to the nutrients. Additional organization of the network is likely achieved through physical interaction, as determined via probing ∼2000 interactions by bacterial two-hybrid assays...
January 8, 2018: Journal of Bacteriology
Benjamin R Pursley, Michael M Maiden, Meng-Lun Hsieh, Nicolas Fernandez, Geoffrey B Severin, Christopher M Waters
Cyclic di-GMP (c-di-GMP) is a bacterial second messenger molecule that is a key global regulator in Vibrio cholerae, but the molecular mechanisms by which this molecule regulates downstream phenotypes have not been fully characterized. One such regulatory factor that may respond to c-di-GMP is the Vc2 c-di-GMP-binding riboswitch that is hypothesized to control the expression of the downstream putative transcription factor TfoY. Although much is known about the physical and structural properties of the Vc2 riboswitch aptamer, the nature of its expression and function in V...
January 8, 2018: Journal of Bacteriology
Jochen Schmid, Broder Rühmann, Volker Sieber, Lorena Romero-Jiménez, Juan Sanjuán, Daniel Pérez-Mendoza
Bacterial exopolysaccharides (EPS) often confer a survival advantage by protecting the cell against abiotic and biotic stresses, including host defensive factors. They are also main components of the extracellular matrix involved in cell-cell recognition, surface adhesion and biofilm formation. Biosynthesis of a growing number of EPS has been reported to be regulated by the ubiquitous second messenger c-di-GMP, which promotes the transition to a biofilm mode of growth in an intimate association with the eukaryotic host...
2018: Methods in Molecular Biology
Carlos Díaz-Salazar, Patricia Calero, Rocío Espinosa-Portero, Alicia Jiménez-Fernández, Lisa Wirebrand, María G Velasco-Domínguez, Aroa López-Sánchez, Victoria Shingler, Fernando Govantes
Biofilm dispersal is a genetically programmed response enabling bacterial cells to exit the biofilm in response to particular physiological or environmental conditions. In Pseudomonas putida biofilms, nutrient starvation triggers c-di-GMP hydrolysis by phosphodiesterase BifA, releasing inhibition of protease LapG by the c-di-GMP effector protein LapD, and resulting in proteolysis of the adhesin LapA and the subsequent release of biofilm cells. Here we demonstrate that the stringent response, a ubiquitous bacterial stress response, is accountable for relaying the nutrient stress signal to the biofilm dispersal machinery...
December 22, 2017: Scientific Reports
Petya Violinova Krasteva, Joaquin Bernal-Bayard, Laetitia Travier, Fernando Ariel Martin, Pierre-Alexandre Kaminski, Gouzel Karimova, Rémi Fronzes, Jean-Marc Ghigo
Secreted exopolysaccharides present important determinants for bacterial biofilm formation, survival, and virulence. Cellulose secretion typically requires the concerted action of a c-di-GMP-responsive inner membrane synthase (BcsA), an accessory membrane-anchored protein (BcsB), and several additional Bcs components. Although the BcsAB catalytic duo has been studied in great detail, its interplay with co-expressed subunits remains enigmatic. Here we show that E. coli Bcs proteins partake in a complex protein interaction network...
December 12, 2017: Nature Communications
Ahmed M Elbakush, Kurt W Miller, Mark Gomelsky
Elevated levels of the second messenger c-di-GMP suppress virulence in diverse pathogenic bacteria, yet mechanisms are poorly characterized. In the food-borne pathogen Listeria monocytogenes, high c-di-GMP levels inhibit mammalian cell invasion. Here, we show that invasion is impaired because of the decreased expression of internalin genes whose products are involved in invasion. We further show that at high c-di-GMP levels, expression of the entire virulence regulon is suppressed and so is expression of the prfA gene encoding the master activator of the virulence regulon...
December 11, 2017: Journal of Bacteriology
Nikola Strempel, Michael Nusser, Anke Neidig, Gerald Brenner-Weiss, Joerg Overhage
The opportunistic human pathogen Pseudomonas aeruginosa is able to survive under a variety of often harmful environmental conditions due to a multitude of intrinsic and adaptive resistance mechanisms, including biofilm formation as one important survival strategy. Here, we investigated the adaptation of P. aeruginosa PAO1 to hypochlorite (HClO), a phagocyte-derived host defense compound and frequently used disinfectant. In static biofilm assays, we observed a significant enhancement in initial cell attachment in the presence of sublethal HClO concentrations...
2017: Frontiers in Microbiology
Feng Wang, Qing He, Kaixuan Su, Tiandi Wei, Sujuan Xu, Lichuan Gu
The Asp-His-His and Asp-His-His-associated (DHH/DHHA1) domain-containing phosphodiesterases (PDEs) that catalyze degradation of cyclic di-adenosine monophosphate (c-di-AMP) could be subdivided into two subfamilies based on the final product is 5'-phosphadenylyl-adenosine (5'-pApA) or AMP. In previous study we revealed that Rv2837c, a stand-alone DHH/DHHA1 PDE, employs a 5'-pApA internal flipping mechanism to produce AMPs. However, why the membrane-bound DHH/DHHA1 PDE can only degrade c-di-AMP to 5'-pApA remains obscure...
December 4, 2017: Biochemical Journal
Sundharraman Subramanian, Xiaohui Gao, Charles E Dann, Daniel B Kearns
Stator elements consisting of MotA4MotB2 complexes are anchored to the cell wall, extend through the cell membrane, and interact with FliG in the cytoplasmic C ring rotor of the flagellum. The cytoplasmic loop of MotA undergoes proton-driven conformational changes that drive flagellar rotation. Functional regulators inhibit motility by either disengaging or jamming the stator-rotor interaction. Here we show that the YcgR homolog MotI (formerly DgrA) of Bacillus subtilis inhibits motility like a molecular clutch that disengages MotA...
December 1, 2017: Proceedings of the National Academy of Sciences of the United States of America
Bandita Poudyal, Karin Sauer
A hallmark of biofilms is their tolerance to killing by antimicrobial agents. In P. aeruginosa, biofilm drug tolerance requires the c-di-GMP responsive, MerR transcriptional regulator BrlR. However, the mechanism by which BrlR mediates biofilm drug tolerance has not been elucidated. Here, we demonstrate that BrlR activates the expression of at least 7 ABC transport systems, including PA1874-77, with ChIP and DNA binding assays confirming BrlR binding to the promoter region of PA1874-77. Insertional inactivation of the 7 ABC transport systems rendered P...
November 27, 2017: Antimicrobial Agents and Chemotherapy
David A Rosen, Joy Twentyman, David A Hunstad
The bacterial second messenger, bis-(3' -5')-cyclic dimeric guanosine monophosphate (c-di-GMP) has been shown to influence expression of virulence factors in certain pathogenic bacteria, but little is known about its activity in the increasingly antibiotic-resistant pathogen Klebsiella pneumoniae Here, expression in K. pneumoniae of a heterologous diguanylate cyclase increased bacterial c-di-GMP concentration and attenuated pathogenesis in murine pneumonia. This attenuation remained evident in mice lacking the c-di-GMP sensor STING, indicating that high c-di-GMP exerted its influence not on host responses, but on bacterial physiology...
November 20, 2017: Infection and Immunity
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