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Bacterial signal transduction

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https://www.readbyqxmd.com/read/28429713/gating-of-tonb-dependent-transporters-by-substrate-specific-forced-remodelling
#1
Samuel J Hickman, Rachael E M Cooper, Luca Bellucci, Emanuele Paci, David J Brockwell
Membrane proteins play vital roles in inside-out and outside-in signal transduction by responding to inputs that include mechanical stimuli. Mechanical gating may be mediated by the membrane or by protein(s) but evidence for the latter is scarce. Here we use force spectroscopy, protein engineering and bacterial growth assays to investigate the effects of force on complexes formed between TonB and TonB-dependent transporters (TBDT) from Gram-negative bacteria. We confirm the feasibility of protein-only mediated mechanical gating by demonstrating that the interaction between TonB and BtuB (a TBDT) is sufficiently strong under force to create a channel through the TBDT...
April 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28409190/methyl-accepting-chemotaxis-proteins-a-core-sensing-element-in-prokaryotes-and-archaea
#2
REVIEW
Abu Iftiaf Md Salah Ud-Din, Anna Roujeinikova
Chemotaxis is the directed motility by means of which microbes sense chemical cues and relocate towards more favorable environments. Methyl-accepting chemotaxis proteins (MCPs) are the most common receptors in bacteria and archaea. They are arranged as trimers of dimers that, in turn, form hexagonal arrays in the cytoplasmic membrane or in the cytoplasm. Several different classes of MCPs have been identified according to their ligand binding region and membrane topology. MCPs have been further classified based on the length and sequence conservation of their cytoplasmic domains...
April 13, 2017: Cellular and Molecular Life Sciences: CMLS
https://www.readbyqxmd.com/read/28399655/cyclic-gmp-amp-as-an-endogenous-second-messenger-in-innate-immune-signaling-by-cytosolic-dna
#3
Kazuki Kato, Hiroki Omura, Ryuichiro Ishitani, Osamu Nureki
The innate immune system functions as the first line of defense against invading bacteria and viruses. In this context, the cGAS/STING [cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase/ STING] signaling axis perceives the nonself DNA associated with bacterial and viral infections, as well as the leakage of self DNA by cellular dysfunction and stresses, to elicit the host's immune responses. In this pathway, the noncanonical cyclic dinucleotide 2',3'-cyclicGMP-AMP(2',3'-cGAMP) functions as a second messenger for signal transduction: 2',3'-cGAMP is produced by the enzyme cGAS upon its recognition of double-stranded DNA, and then the 2',3'-cGAMP is recognized by the receptor STING to induce the phosphorylation of downstream factors, including TBK1 (TANK binding kinase 1) and IRF3 (interferon regulatory factor 3)...
April 7, 2017: Annual Review of Biochemistry
https://www.readbyqxmd.com/read/28396915/different-nitrogen-sources-change-the-transcriptome-of-welan-gum-producing-strain-sphingomonas-sp-atcc-31555
#4
Xiaopeng Xu, Zuoming Nie, Zhiyong Zheng, Li Zhu, Hongtao Zhang, Xiaobei Zhan
To reveal effects of different nitrogen sources on the expressions and functions of genes in Sphingomonas sp. ATCC 31555, it was cultivated in medium containing inorganic nitrogen (IN), organic nitrogen (ON), or inorganic-organic combined nitrogen (CN). Welan gum production and bacterial biomass were determined, and RNA sequencing (RNA-seq) was performed. Differentially expressed genes (DEGs) between the different ATCC 31555 groups were identified, and their functions were analyzed. Welan gum production and bacterial biomass were significantly higher in the ON and CN groups compared with those in the IN group...
April 10, 2017: Archives of Microbiology
https://www.readbyqxmd.com/read/28380509/identification-of-loci-associated-with-susceptibility-to-subspecies-tissue-infection-in-cattle
#5
J N Kiser, S N White, K A Johnson, J L Hoff, J F Taylor, H L Neibergs
Johne's disease is a contagious bacterial infection of cattle caused by ssp. (). A previous genome-wide association analysis (GWAA) in Holstein cattle identified QTL on BTA3 and BTA9 that were highly associated (P < 5 × 10) and on BTA1, BTA16, and BTA21 that were moderately associated (P < 5 × 10) with Map tissue infection. The objectives of this study were to validate previous GWAA results in Jersey cattle ( = 57), Holstein cattle from the Pacific Northwest (PNW, = 205) and a combined Holstein population from the PNW and the Northeast (PNW + NE, = 423), and also identify new loci associated with tissue infection...
March 2017: Journal of Animal Science
https://www.readbyqxmd.com/read/28375740/experimentally-dissecting-the-origins-of-peroxiredoxin-catalysis
#6
Kimberly J Nelson, Arden Perkins, Amanda E D Van Swearingen, Steven Hartman, Andrew E Brereton, Derek Parsonage, Freddie R Salsbury, P Andrew Karplus, Leslie B Poole
AIMS: Peroxiredoxins (Prxs) are ubiquitous cysteine-based peroxidases involved in oxidant defense and signal transduction. Despite much study, the precise roles of conserved residues remain poorly defined. In this study, we carried out extensive functional and structural characterization of 10 variants of such residues in a model decameric bacterial Prx. RESULTS: Three active site proximal mutations of Salmonella typhimurium AhpC, T43V, R119A, and E49Q, lowered catalytic efficiency with hydrogen peroxide by 4-5 orders of magnitude, but did not affect reactivity toward their reductant, AhpF...
April 4, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28361445/roles-of-probiotic-lactobacilli-inclusion-in-helping-piglets-establish-healthy-intestinal-inter-environment-for-pathogen-defense
#7
REVIEW
Jiajun Yang, Kun Qian, Chonglong Wang, Yijing Wu
The gastrointestinal tract of pigs is densely populated with microorganisms that closely interact with the host and with ingested feed. Gut microbiota benefits the host by providing nutrients from dietary substrates and modulating the development and function of the digestive and immune systems. An optimized gastrointestinal microbiome is crucial for pigs' health, and establishment of the microbiome in piglets is especially important for growth and disease resistance. However, the microbiome in the gastrointestinal tract of piglets is immature and easily influenced by the environment...
March 30, 2017: Probiotics and Antimicrobial Proteins
https://www.readbyqxmd.com/read/28338646/type-iv-secretion-and-signal-transduction-of-helicobacter-pylori-caga-through-interactions-with-host-cell-receptors
#8
REVIEW
Steffen Backert, Nicole Tegtmeyer
Helicobacter pylori is a highly successful human bacterium, which is exceptionally equipped to persistently inhabit the human stomach. Colonization by this pathogen is associated with gastric disorders ranging from chronic gastritis and peptic ulcers to cancer. Highly virulent H. pylori strains express the well-established adhesins BabA/B, SabA, AlpA/B, OipA, and HopQ, and a type IV secretion system (T4SS) encoded by the cag pathogenicity island (PAI). The adhesins ascertain intimate bacterial contact to gastric epithelial cells, while the T4SS represents an extracellular pilus-like structure for the translocation of the effector protein CagA...
March 24, 2017: Toxins
https://www.readbyqxmd.com/read/28322874/reconstructing-the-genotype-to-fitness-map-for-the-bacterial-chemotaxis-network-and-its-emergent-behavioural-phenotypes
#9
Alberto Nakauma, G Sander van Doorn
The signal-transduction network responsible for chemotaxis in Escherichia coli has been characterised in extraordinary detail. Yet, relatively little is known about eco-evolutionary aspects of chemotaxis, such as how the network has been shaped by selection and to what extent natural populations may fine-tune their chemotactic behaviour to the ecological conditions. To address these questions, we here develop an evolutionary-systems-biology model of the chemotaxis network of E. coli, which we apply to estimate the resource accumulation rate (here used as a proxy for fitness) of wildtype and a large number of potential mutant genotypes...
March 18, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28319728/modulation-of-host-cell-apoptotic-pathways-by-intracellular-pathogens
#10
REVIEW
Anja Friedrich, Julian Pechstein, Christian Berens, Anja Lührmann
Nearly all steps of the host cell apoptotic cascade can be subverted by intracellular microorganisms. Some pathogens modulate early steps and interfere with sensing of extracellular signals, cellular stress or signal transduction; others target Bcl-2 proteins, caspases, or inhibitor of apoptosis proteins (IAPs). In many cases the exact molecular mechanisms leading to interference with the host cell apoptotic cascade are still unknown. However, there are some examples where bacterial factors that modulate host cell death have been identified...
March 17, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/28314727/transcriptomic-analyses-elucidate-adaptive-differences-of-closely-related-strains-of-p-aeruginosa-in-fuel
#11
Thusitha S Gunasekera, Loryn L Bowen, Carol E Zhou, Susan C Howard-Byerly, William S Foley, Richard C Striebich, Larry C Dugan, Oscar N Ruiz
Pseudomonas aeruginosa can utilize hydrocarbons, but different strains have varying degrees of adaptation despite their highly conserved genome. P. aeruginosa ATCC 33988 is highly adapted to hydrocarbons while strain PAO1, a human pathogen, is less-adapted and degrades jet fuel at a slower rate than does ATCC 33988. We investigated fuel specific transcriptomic differences between these strains in order to ascertain the underling mechanisms utilized by the adapted strain to proliferate in fuel. During growth in fuel, the genes related to alkane degradation, heat-shock response, membrane proteins, efflux pumps and several novel genes were upregulated in ATCC 33988...
March 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28301773/progress-and-potential-of-electron-cryotomography-as-illustrated-by-its-application-to-bacterial-chemoreceptor-arrays
#12
Ariane Briegel, Grant Jensen
Electron cryotomography (ECT) can produce three-dimensional images of biological samples such as intact cells in a near-native, frozen-hydrated state to macromolecular resolution (∼4 nm). Because one of its first and most common applications has been to bacterial chemoreceptor arrays, ECT's contributions to this field illustrate well its past, present, and future. Although X-ray crystallography and nuclear magnetic resonance spectroscopy have revealed the structures of nearly all the individual components of chemoreceptor arrays, ECT has revealed the mesoscale information about how the components are arranged within cells...
February 23, 2017: Annual Review of Biophysics
https://www.readbyqxmd.com/read/28271471/structure-and-function-of-the-stressosome-signalling-hub
#13
Jan Pané-Farré, Maureen B Quin, Richard J Lewis, Jon Marles-Wright
The stressosome is a multi-protein signal integration and transduction hub found in a wide range of bacterial species. The role that the stressosome plays in regulating the transcription of genes involved in the general stress response has been studied most extensively in the Gram-positive model organism Bacillus subtilis. The stressosome receives and relays the signal(s) that initiate a complex phosphorylation-dependent partner switching cascade, resulting in the activation of the alternative sigma factor σ(B)...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28270586/emergent-phototactic-responses-of-cyanobacteria-under-complex-light-regimes
#14
Rosanna Man Wah Chau, Devaki Bhaya, Kerwyn Casey Huang
Environmental cues can stimulate a variety of single-cell responses, as well as collective behaviors that emerge within a bacterial community. These responses require signal integration and transduction, which can occur on a variety of time scales and often involve feedback between processes, for example, between growth and motility. Here, we investigate the dynamics of responses of the phototactic, unicellular cyanobacterium Synechocystis sp. PCC6803 to complex light inputs that simulate the natural environments that cells typically encounter...
March 7, 2017: MBio
https://www.readbyqxmd.com/read/28264991/giga-and-gigb-are-master-regulators-of-antibiotic-resistance-stress-responses-and-virulence-in-acinetobacter-baumannii
#15
Michael J Gebhardt, Howard A Shuman
A critical component of bacterial pathogenesis is the ability of an invading organism to sense and adapt to the harsh environment imposed by the host's immune system. This is especially important for opportunistic pathogens, such as Acinetobacter baumannii, a nutritionally versatile, environmental organism that has recently gained attention as a life-threatening human pathogen. The emergence of A. baumannii is closely linked to antibiotic resistance and many contemporary isolates are multi-drug resistant (MDR)...
March 6, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28249794/identification-of-mycobacterial-gara-as-a-substrate-of-protein-kinase-g-from-m-tuberculosis-using-a-kestrel-based-proteome-wide-approach
#16
Philipp Mueller, Jean Pieters
Signal transduction in bacteria is generally mediated via two-component systems. These systems depend on the transfer of a phosphate molecule from a donor to an acceptor by histidine kinases, thereby activating the acceptor to allow downstream signaling/activation. Several bacterial genomes, including the genome of M. tuberculosis, were shown to encode eukaryotic-like kinases. To better understand the function of these kinases and the regulatory networks within which they operate, identification of downstream targets is essential...
February 27, 2017: Journal of Microbiological Methods
https://www.readbyqxmd.com/read/28237903/exploring-functional-membrane-microdomains-in-bacteria-an-overview
#17
REVIEW
Daniel Lopez, Gudrun Koch
Recent studies show that internal organization of bacterial cells is more complex than previously appreciated. A clear example of this is the assembly of the nanoscale membrane platforms termed functional membrane microdomains. The lipid composition of these regions differs from that of the surrounding membrane; these domains confine a set of proteins involved in specific cellular processes such as protease secretion and signal transduction. It is currently thought that functional membrane microdomains act as oligomerization platforms and promote efficient oligomerization of interacting protein partners in bacterial membranes...
February 23, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/28230048/differential-regulation-of-the-epr3-receptor-coordinates-membrane-restricted-rhizobial-colonization-of-root-nodule-primordia
#18
Yasuyuki Kawaharada, Mette W Nielsen, Simon Kelly, Euan K James, Kasper R Andersen, Sheena R Rasmussen, Winnie Füchtbauer, Lene H Madsen, Anne B Heckmann, Simona Radutoiu, Jens Stougaard
In Lotus japonicus, a LysM receptor kinase, EPR3, distinguishes compatible and incompatible rhizobial exopolysaccharides at the epidermis. However, the role of this recognition system in bacterial colonization of the root interior is unknown. Here we show that EPR3 advances the intracellular infection mechanism that mediates infection thread invasion of the root cortex and nodule primordia. At the cellular level, Epr3 expression delineates progression of infection threads into nodule primordia and cortical infection thread formation is impaired in epr3 mutants...
February 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28220253/myd88-in-mycobacterium-tuberculosis-infection
#19
EDITORIAL
Jorge L Cervantes
MyD88 adaptor protein mediates numerous biologically important signal transduction pathways in innate immunity. MyD88 signaling fosters bacterial containment and is necessary to raise an adequate innate and acquired immune response to Mycobacterium tuberculosis (Mtb). The phagosome is a crucial cellular location not only for Mtb replication, but it is also where components of the Myddosome and inflammasome are recruited. Besides its function as a TLR-adaptor protein, MyD88 may help stabilizing cytosolic receptors that are recruited to the phagosome...
February 20, 2017: Medical Microbiology and Immunology
https://www.readbyqxmd.com/read/28217110/intra-species-and-inter-kingdom-signaling-of-legionella-pneumophila
#20
REVIEW
Ramon Hochstrasser, Hubert Hilbi
The ubiquitous Gram-negative bacterium Legionella pneumophila parasitizes environ mental amoebae and, upon inhalation, replicates in alveolar macrophages, thus causing a life-threatening pneumonia called "Legionnaires' disease." The opportunistic pathogen employs a bi-phasic life cycle, alternating between a replicative, non-virulent phase and a stationary, transmissive/virulent phase. L. pneumophila employs the Lqs (Legionella quorum sensing) system as a major regulator of the growth phase switch. The Lqs system comprises the autoinducer synthase LqsA, the homologous sensor kinases LqsS and LqsT, as well as a prototypic response regulator termed LqsR...
2017: Frontiers in Microbiology
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