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Luisa F Castiblanco, George W Sundin
Bacterial biofilms are multicellular aggregates encased in an extracellular matrix mainly composed of exopolysaccharides (EPSs), protein, and nucleic acids, which determines the architecture of the biofilm. Erwinia amylovora Ea1189 forms a biofilm inside the xylem of its host, that results in vessel plugging and water transport impairment. Production of the EPSs amylovoran and levan are critical for the formation of a mature biofilm. Additionally, cyclic dimeric GMP (c-di-GMP) was reported to positively regulate amylovoran biosynthesis and biofilm formation in E...
October 18, 2016: Molecular Plant Pathology
Yujie Xiao, Hailing Nie, Huizhong Liu, Wenli Chen, Qiaoyun Huang
Cyclic di-GMP (c-di-GMP), a ubiquitous bacterial second messenger that regulates diverse cellular processes, is synthesized by diguanylate cyclase (DGC) and degraded by phosphodiesterase (PDE). GcbA is a well conserved DGC among Pseudomonas species, and has been reported to influence biofilm formation and flagellar motility in Pseudomonas fluorescens and Pseudomonas aeruginosa. Here we confirm the function of GcbA in Pseudomonas putida and reveal that expression of GcbA is regulated by FleQ in response to c-di-GMP...
October 4, 2016: Environmental Microbiology Reports
Mona W Orr, Michael Y Galperin, Vincent T Lee
Bacteria utilize a diverse set of nucleotide second messengers to regulate cellular responses by binding macromolecular receptors (RNAs and proteins). Recent studies on cyclic di-GMP (c-di-GMP) have shown that this signaling molecule binds multiple receptors to regulate different steps in the same biological process. We propose this property of the same molecule regulating multiple steps in the same process is biologically meaningful and have termed this phenomenon 'sustained sensing'. Here, we discuss the recent findings that support the concept of sustained sensing of c-di-GMP levels and provide additional examples that support the utilization of sustained sensing by other second messengers...
October 1, 2016: Current Opinion in Microbiology
Regine Hengge
The bacterial second messenger c-di-GMP controls bacterial biofilm formation, motility, cell cycle progression, development and virulence. It is synthesized by diguanylate cyclases (with GGDEF domains), degraded by specific phosphodiesterases (PDEs, with EAL of HD-GYP domains) and sensed by a wide variety of c-di-GMP-binding effectors that control diverse targets. c-di-GMP-binding effectors can be riboswitches as well as proteins with highly diverse structures and functions. The latter include 'degenerate' GGDEF/EAL domain proteins that are enzymatically inactive but still able to bind c-di-GMP...
November 5, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Mike Khan, Jerome S Harms, Fernanda M Marim, Leah Armon, Cherisse L Hall, Yi-Ping Liu, Menachem Banai, Sergio C Oliveira, Gary A Splitter, Judith A Smith
Brucella species are facultative intracellular bacteria that cause brucellosis, a chronic debilitating disease significantly impacting global health and prosperity. Much remains to be learned about how Brucella spp. succeed in sabotaging immune host cells and how Brucella respond to environmental challenges. Multiple types of bacteria employ the prokaryotic second messenger cyclic-di-GMP (c-di-GMP) to coordinate responses to shifting environments. To determine the role of c-di-GMP in Brucella physiology and in shaping host-Brucella interactions, we utilized c-di-GMP regulatory enzyme deletion mutants...
September 26, 2016: Infection and Immunity
Walaa K Mousa, Charles Shearer, Victor Limay-Rios, Cassie L Ettinger, Jonathan A Eisen, Manish N Raizada
The ancient African crop, finger millet, has broad resistance to pathogens including the toxigenic fungus Fusarium graminearum. Here, we report the discovery of a novel plant defence mechanism resulting from an unusual symbiosis between finger millet and a root-inhabiting bacterial endophyte, M6 (Enterobacter sp.). Seed-coated M6 swarms towards root-invading Fusarium and is associated with the growth of root hairs, which then bend parallel to the root axis, subsequently forming biofilm-mediated microcolonies, resulting in a remarkable, multilayer root-hair endophyte stack (RHESt)...
2016: Nature Microbiology
Jie Zhou, Benjamin T Roembke, Gabor Paragi, Aurélien Laguerre, Herman O Sintim, Célia Fonseca Guerra, David Monchaud
A twice-as-smart ligand is a small molecule that experiences a structural switch upon interaction with its target (i.e., smart ligand) that concomitantly triggers its fluorescence (i.e., smart probe). Prototypes of twice-as-smart ligands were recently developed to track and label G-quadruplexes: these higher-order nucleic acid structures originate in the assembly of four guanine(G)-rich DNA or RNA strands, whose stability is imparted by the formation and the self-assembly of G-quartets. The first prototypes of twice-as-smart quadruplex ligands were designed to exploit the self-association of quartets, being themselves synthetic G-quartets...
September 26, 2016: Scientific Reports
Yujie Xiao, Huizhong Liu, Hailing Nie, Shan Xie, Xuesong Luo, Wenli Chen, Qiaoyun Huang
Flagella-mediated motility is an important capability of many bacteria to survive in nutrient-depleted and harsh environments. Decreasing the intracellular cyclic di-GMP (c-di-GMP) level by overexpression of phosphodiesterase BifA promotes flagellar-mediated motility and induces planktonic lifestyle in Pseudomonas. The mechanism that regulates expression of bifA gene was poorly studied. Here we showed that expression of BifA was partly controlled by flagellar sigma factor FliA (σ(28) ) in Pseudomonas putidaKT2440...
September 23, 2016: MicrobiologyOpen
Chunli Wan, Yanggui Shen, Si Chen, Xiang Liu, Guangmin Liu, Juin-Yih Lai, Duu-Jong Lee
This study revealed that the gross indicators commonly adopted for monitoring the performance of aerobic granular sludge processes are not capable of probing the microstructural deterioration of granule interior upon organic loading swaps. These granules subjected to loading swaps retained their global characteristics: appearances, sizes and settling velocities, chemical oxygen demand (COD) and ammonia-nitrogen removal capacities. However, the granule interior strength, as determined by ultrasound method, was largely weakened upon COD switch-off and was not recovered in the subsequent COD re-supply stage...
December 2016: Bioresource Technology
Badri N Dubey, Christian Lori, Shogo Ozaki, Geoffrey Fucile, Ivan Plaza-Menacho, Urs Jenal, Tilman Schirmer
Histidine kinases are key components of regulatory networks in bacteria. Although many of these enzymes are bifunctional, mediating both phosphorylation and dephosphorylation of downstream targets, the molecular details of this central regulatory switch are unclear. We showed recently that the universal second messenger cyclic di-guanosine monophosphate (c-di-GMP) drives Caulobacter crescentus cell cycle progression by forcing the cell cycle kinase CckA from its default kinase into phosphatase mode. We use a combination of structure determination, modeling, and functional analysis to demonstrate that c-di-GMP reciprocally regulates the two antagonistic CckA activities through noncovalent cross-linking of the catalytic domain with the dimerization histidine phosphotransfer (DHp) domain...
September 2016: Science Advances
Ching-Ting Lin, Tien-Huang Lin, Chien-Chen Wu, Lei Wan, Chun-Fa Huang, Hwei-Ling Peng
Klebsiella pneumoniae is the predominant pathogen isolated from liver abscesses of diabetic patients in Asian countries. However, the effects of elevated blood glucose levels on the virulence of this pathogen remain largely unknown. Type 3 fimbriae, encoded by the mrkABCDF genes, are important virulence factors in K. pneumoniae pathogenesis. In this study, the effects of exogenous glucose and the intracellular cyclic AMP (cAMP) signaling pathway on type 3 fimbriae expression regulation were investigated. The production of MrkA, the major subunit of type 3 fimbriae, was increased in glucose-rich medium, whereas cAMP supplementation reversed the effect...
2016: PloS One
Jonas Stenløkke Madsen, Leise Riber, Witold Kot, Alrun Basfeld, Mette Burmølle, Lars Hestbjerg Hansen, Søren Johannes Sørensen
Horizontal gene transfer (HGT), the transmission of genetic material to a recipient that is not the progeny of the donor, is fundamental in bacterial evolution. HGT is often mediated by mobile genetic elements such as conjugative plasmids, which may be in conflict with the chromosomal elements of the genome because they are independent replicons that may petition their own evolutionary strategy. Here we study differences between type 3 fimbriae encoded on wild type plasmids and in chromosomes. Using known and newly characterized plasmids we show that the expression of type 3 fimbriae encoded on plasmids is systematically different, as MrkH, a c-di-GMP dependent transcriptional activator is not needed for strong expression of the fimbriae...
2016: PloS One
Zhixin Zhao, Zhen Wu, Jun Zhang
As an important bacterial second messenger, bis-(3',5')-cyclic diguanylate (cyclic di-GMP or c-di-GMP) has been implicated in numerous biological activities, including biofilm formation, motility, survival and virulence. These processes are manipulated by the binding of c-di-GMP to its receptors. XC_3703 from the plant pathogen Xanthomonas campestris pv. campestris, which belongs to the YajQ family of proteins, has recently been identified as a potential c-di-GMP receptor. XC_3703, together with XC_2801, functions as a transcription factor activating virulence-related genes, which can be reversed by the binding of c-di-GMP to XC_3703...
September 2016: Acta Crystallographica. Section F, Structural Biology Communications
Naomi Attar
No abstract text is available yet for this article.
October 2016: Nature Reviews. Microbiology
Yu-Chuan Wang, Ko-Hsin Chin, Zhi-Le Tu, Jin He, Christopher J Jones, David Zamorano Sanchez, Fitnat H Yildiz, Michael Y Galperin, Shan-Ho Chou
C-di-GMP is a bacterial second messenger regulating various cellular functions. Many bacteria contain c-di-GMP-metabolizing enzymes but lack known c-di-GMP receptors. Recently, two MshE-type ATPases associated with bacterial type II secretion system and type IV pilus formation were shown to specifically bind c-di-GMP. Here we report crystal structure of the MshE N-terminal domain (MshEN1-145) from Vibrio cholerae in complex with c-di-GMP at a 1.37 Å resolution. This structure reveals a unique c-di-GMP-binding mode, featuring a tandem array of two highly conserved binding motifs, each comprising a 24-residue sequence RLGxx(L/V/I)(L/V/I)xxG(L/V/I)(L/V/I)xxxxLxxxLxxQ that binds half of the c-di-GMP molecule, primarily through hydrophobic interactions...
2016: Nature Communications
Maria A Schumacher, Wenjie Zeng
The pathogenesis of Klebsiella pneumonia is linked to the bacteria's ability to form biofilms. Mannose-resistant Klebsiella-like (Mrk) hemagglutinins are critical for K pneumonia biofilm development, and the expression of the genes encoding these proteins is activated by a 3',5'-cyclic diguanylic acid (c-di-GMP)-regulated transcription factor, MrkH. To gain insight into MrkH function, we performed structural and biochemical analyses. Data revealed MrkH to be a monomer with a two-domain architecture consisting of a PilZ C-domain connected to an N domain that unexpectedly also harbors a PilZ-like fold...
September 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
César Pedroza-Roldán, Carolina Guapillo, Jorge Barrios-Payán, Dulce Mata-Espinosa, Michel de Jesús Aceves-Sánchez, Brenda Marquina-Castillo, Rogelio Hernández-Pando, Mario Alberto Flores-Valdez
Mycobacterium tuberculosis (Mtb) has been a threat to humans since ancient times, and it is the main causative agent of tuberculosis (TB). Until today, the only licensed vaccine against Mtb is the live attenuated M. bovis Bacillus Calmette-Guérin (BCG), which has variable levels of protection against the pulmonary form of infection. The quest for a new vaccine is a priority given the rise of multidrug-resistant Mtb around the world, as well as the tremendous burden imposed by latent TB. The objective of this study was to evaluate the immunogenicity and capacity of protection of a modified BCG strain (BCGΔBCG1419c) lacking the c-di-GMP phosphodiesterase gene BCG1419c, in diverse mice models...
September 14, 2016: Vaccine
Cristina Latasa, Maite Echeverz, Begoña García, Carmen Gil, Enrique García-Ona, Saioa Burgui, Noelia Casares, Sandra Hervás-Stubbs, Juan José Lasarte, Iñigo Lasa, Cristina Solano
Salmonellosis is one of the most important bacterial zoonotic diseases transmitted through the consumption of contaminated food, with chicken and pig related products being key reservoirs of infection. Although numerous studies on animal vaccination have been performed in order to reduce Salmonella prevalence, there is still a need for an ideal vaccine. Here, with the aim of constructing a novel live attenuated Salmonella vaccine candidate, we firstly analyzed the impact of the absence of cyclic-di-GMP (c-di-GMP) in Salmonella virulence...
2016: PloS One
Julie Groizeleau, Morten Rybtke, Jens Bo Andersen, Jens Berthelsen, Yang Liu, Liang Yang, Thomas E Nielsen, Volkhard Kaever, Michael Givskov, Tim Tolker-Nielsen
Current antibiotic treatments are insufficient in eradicating bacterial biofilms, which represent the primary cause of chronic bacterial infections. Thus, there is an urgent need for new strategies to eradicate biofilm infections. The second messenger c-di-GMP is a positive regulator of biofilm formation in many clinically relevant bacteria. It is hypothesized that drugs that lower the intracellular level of c-di-GMP will force biofilm bacteria into a more treatable planktonic lifestyle. To identify compounds capable of lowering c-di-GMP levels in Pseudomonas aeruginosa, we screened 5000 compounds for their potential c-di-GMP lowering effect using a recently developed c-di-GMP biosensor strain...
August 15, 2016: Microbiology
Hyo Kyung Kim, Rasika M Harshey
UNLABELLED: Cell division arrest is a universal checkpoint in response to environmental assaults that generate cellular stress. In bacteria, the cyclic di-GMP (c-di-GMP) signaling network is one of several signal transduction systems that regulate key processes in response to extra-/intracellular stimuli. Here, we find that the diguanylate cyclase YfiN acts as a bifunctional protein that produces c-di-GMP in response to reductive stress and then dynamically relocates to the division site to arrest cell division in response to envelope stress in Escherichia coli YfiN localizes to the Z ring by interacting with early division proteins and stalls cell division by preventing the initiation of septal peptidoglycan synthesis...
2016: MBio
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