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PubMed Central (PMC3 - NLM DTD) (2.636.741 recursos)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).

Journal of Bacteriology

Mostrando recursos 1 - 20 de 94.656

1. New Family of Tungstate-Responsive Transcriptional Regulators in Sulfate-Reducing Bacteria - Kazakov, Alexey E.; Rajeev, Lara; Luning, Eric G.; Zane, Grant M.; Siddartha, Kavya; Rodionov, Dmitry A.; Dubchak, Inna; Arkin, Adam P.; Wall, Judy D.; Mukhopadhyay, Aindrila; Novichkov, Pavel S.
The trace elements molybdenum and tungsten are essential components of cofactors of many metalloenzymes. However, in sulfate-reducing bacteria, high concentrations of molybdate and tungstate oxyanions inhibit growth, thus requiring the tight regulation of their homeostasis. By a combination of bioinformatic and experimental techniques, we identified a novel regulator family, tungstate-responsive regulator (TunR), controlling the homeostasis of tungstate and molybdate in sulfate-reducing deltaproteobacteria. The effector-sensing domains of these regulators are similar to those of the known molybdate-responsive regulator ModE, while their DNA-binding domains are homologous to XerC/XerD site-specific recombinases. Using a comparative genomics approach, we identified DNA motifs and reconstructed regulons...

2. TraG Encoded by the pIP501 Type IV Secretion System Is a Two-Domain Peptidoglycan-Degrading Enzyme Essential for Conjugative Transfer - Arends, Karsten; Celik, Ertugrul-Kaan; Probst, Ines; Goessweiner-Mohr, Nikolaus; Fercher, Christian; Grumet, Lukas; Soellue, Cem; Abajy, Mohammad Yaser; Sakinc, Tuerkan; Broszat, Melanie; Schiwon, Katarzyna; Koraimann, Guenther; Keller, Walter; Grohmann, Elisabeth
pIP501 is a conjugative broad-host-range plasmid frequently present in nosocomial Enterococcus faecalis and Enterococcus faecium isolates. We focus here on the functional analysis of the type IV secretion gene traG, which was found to be essential for pIP501 conjugative transfer between Gram-positive bacteria. The TraG protein, which localizes to the cell envelope of E. faecalis harboring pIP501, was expressed and purified without its N-terminal transmembrane helix (TraGΔTMH) and shown to possess peptidoglycan-degrading activity. TraGΔTMH was inhibited by specific lytic transglycosylase inhibitors hexa-N-acetylchitohexaose and bulgecin A. Analysis of the TraG sequence suggested the presence of two domains which both could contribute...

3. ppGpp Metabolism Is Involved in Heterocyst Development in the Cyanobacterium Anabaena sp. Strain PCC 7120 - Zhang, Shao-Ran; Lin, Gui-Ming; Chen, Wen-Li; Wang, Li; Zhang, Cheng-Cai
When deprived of a combined-nitrogen source in the growth medium, the filamentous cyanobacterium Anabaena sp. PCC 7120 (Anabaena) can form heterocysts capable of nitrogen fixation. The process of heterocyst differentiation takes about 20 to 24 h, during which extensive metabolic and morphological changes take place. Guanosine tetraphosphate (ppGpp) is the signal of the stringent response that ensures cell survival by adjusting major cellular activities in response to nutrient starvation in bacteria, and ppGpp accumulates at the early stage of heterocyst differentiation (J. Akinyanju, R. J. Smith, FEBS Lett. 107:173–176, 1979; J Akinyanju, R. J. Smith, New Phytol. 105:117–122, 1987). Here...

4. Interwoven Biology of the Tsetse Holobiont - Snyder, Anna K.; Rio, Rita V. M.
Microbial symbionts can be instrumental to the evolutionary success of their hosts. Here, we discuss medically significant tsetse flies (Diptera: Glossinidae), a group comprised of over 30 species, and their use as a valuable model system to study the evolution of the holobiont (i.e., the host and associated microbes). We first describe the tsetse microbiota, which, despite its simplicity, harbors a diverse range of associations. The maternally transmitted microbes consistently include two Gammaproteobacteria, the obligate mutualists Wigglesworthia spp. and the commensal Sodalis glossinidius, along with the parasitic Alphaproteobacteria Wolbachia. These associations differ in their establishment times, making them unique and...

5. Characterization of SAV7471, a TetR-Family Transcriptional Regulator Involved in the Regulation of Coenzyme A Metabolism in Streptomyces avermitilis - Liu, Yanping; Yan, Tingting; Jiang, Libin; Wen, Ying; Song, Yuan; Chen, Zhi; Li, Jilun
The role of a tetR transcriptional regulatory gene (SAV7471) in avermectin production in the Gram-positive soil bacterium Streptomyces avermitilis was investigated by gene deletion, complementation, and overexpression experiments. Gene deletion of the SAV7471 open reading frame resulted in avermectin overproduction. The deletion also resulted in overexpression of SAV7472-SAV7473 transcripts, which encode a protein of unknown function and a flavoprotein possibly involved in pantothenate and coenzyme A (CoA) metabolism. EMSAs and footprinting assays showed that SAV7471 can bind to two palindromic sequences with high similarity in the intergenic region between SAV7471 and SAV7472, a region that contains the apparent transcription start...

6. Elucidation of the Role of Clp Protease Components in Circadian Rhythm by Genetic Deletion and Overexpression in Cyanobacteria - Imai, Keiko; Kitayama, Yohko; Kondo, Takao
In the cyanobacterium Synechococcus elongatus PCC7942, KaiA, KaiB, and KaiC are essential elements of the circadian clock, and Kai-based oscillation is thought to be the basic circadian timing mechanism. The Kai-based oscillator coupled with transcription/translation feedback and other intercellular factors maintains the stability of the 24-hour period in vivo. In this study, we showed that disruption of the Clp protease family genes clpP1, clpP2, and clpX and the overexpression of clpP3 cause long-period phenotypes. There were no significant changes in the levels of the clock proteins in these mutants. The overexpression of clpX led to a decrease in kaiBC promoter...

7. Effects of Low PBP2b Levels on Cell Morphology and Peptidoglycan Composition in Streptococcus pneumoniae R6 - Berg, Kari Helene; Stamsås, Gro Anita; Straume, Daniel; Håvarstein, Leiv Sigve
Streptococcus pneumoniae produces two class B penicillin-binding proteins, PBP2x and PBP2b, both of which are essential. It is generally assumed that PBP2x is specifically involved in septum formation, while PBP2b is dedicated to peripheral cell wall synthesis. However, little experimental evidence exists to substantiate this belief. In the present study, we obtained evidence that strongly supports the view that PBP2b is essential for peripheral peptidoglycan synthesis. Depletion of PBP2b expression gave rise to long chains of cells in which individual cells were compressed in the direction of the long axis and looked lentil shaped. This morphological change is consistent with...

8. Eliminating a Set of Four Penicillin Binding Proteins Triggers the Rcs Phosphorelay and Cpx Stress Responses in Escherichia coli - Evans, Kerry L.; Kannan, Suresh; Li, Gang; de Pedro, Miguel A.; Young, Kevin D.
Penicillin binding proteins (PBPs) are responsible for synthesizing and modifying the bacterial cell wall, and in Escherichia coli the loss of several nonessential low-molecular-weight PBPs gives rise to abnormalities in cell shape and division. To determine whether these proteins help connect the flagellar basal body to the peptidoglycan wall, we surveyed a set of PBP mutants and found that motility in an agar migration assay was compromised by the simultaneous absence of four enzymes: PBP4, PBP5, PBP7, and AmpH. A wild-type copy of any one of these restored migration, and complementation depended on the integrity of the PBP active-site serine....

9. NADP-Specific Electron-Bifurcating [FeFe]-Hydrogenase in a Functional Complex with Formate Dehydrogenase in Clostridium autoethanogenum Grown on CO - Wang, Shuning; Huang, Haiyan; Kahnt, Jörg; Mueller, Alexander P.; Köpke, Michael; Thauer, Rudolf K.
Flavin-based electron bifurcation is a recently discovered mechanism of coupling endergonic to exergonic redox reactions in the cytoplasm of anaerobic bacteria and archaea. Among the five electron-bifurcating enzyme complexes characterized to date, one is a heteromeric ferredoxin- and NAD-dependent [FeFe]-hydrogenase. We report here a novel electron-bifurcating [FeFe]-hydrogenase that is NADP rather than NAD specific and forms a complex with a formate dehydrogenase. The complex was found in high concentrations (6% of the cytoplasmic proteins) in the acetogenic Clostridium autoethanogenum autotrophically grown on CO, which was fermented to acetate, ethanol, and 2,3-butanediol. The purified complex was composed of seven different subunits....

10. Mycobacterium tuberculosis Cholesterol Catabolism Requires a New Class of Acyl Coenzyme A Dehydrogenase - Voskuil, Martin I.

11. Topoisomerase I (TopA) Is Recruited to ParB Complexes and Is Required for Proper Chromosome Organization during Streptomyces coelicolor Sporulation - Szafran, Marcin; Skut, Patrycja; Ditkowski, Bartosz; Ginda, Katarzyna; Chandra, Govind; Zakrzewska-Czerwińska, Jolanta; Jakimowicz, Dagmara
Streptomyces species are bacteria that resemble filamentous fungi in their hyphal mode of growth and sporulation. In Streptomyces coelicolor, the conversion of multigenomic aerial hyphae into chains of unigenomic spores requires synchronized septation accompanied by segregation of tens of chromosomes into prespore compartments. The chromosome segregation is dependent on ParB protein, which assembles into an array of nucleoprotein complexes in the aerial hyphae. Here, we report that nucleoprotein ParB complexes are bound in vitro and in vivo by topoisomerase I, TopA, which is the only topoisomerase I homolog found in S. coelicolor. TopA cannot be eliminated, and its depletion inhibits...

12. Posttranslational Maturation of the Invasion Acyl Carrier Protein of Salmonella enterica Serovar Typhimurium Requires an Essential Phosphopantetheinyl Transferase of the Fatty Acid Biosynthesis Pathway - Viala, Julie P. M.; Puppo, Rémy; My, Lætitia; Bouveret, Emmanuelle
Salmonella pathogenicity island 1 (SPI-1) carries genes required for the formation of a type 3 secretion system, which is necessary for the invasion process of Salmonella. Among the proteins encoded by SPI-1 is IacP, a homolog of acyl carrier proteins. Acyl carrier proteins are mainly involved in fatty acid biosynthesis, and they require posttranslational maturation by addition of a 4′-phosphopantetheine prosthetic group to be functional. In this study, we analyzed IacP maturation in vivo. By performing matrix-assisted laser desorption ionization–time-of-flight (MALDI-TOF) mass spectrometry analysis of intact purified proteins, we showed that IacP from Salmonella enterica serovar Typhimurium was matured by...

13. Helicobacter pylori Salvages Purines from Extracellular Host Cell DNA Utilizing the Outer Membrane-Associated Nuclease NucT - Liechti, George W.; Goldberg, Joanna B.
Helicobacter pylori is a bacterial pathogen that establishes life-long infections in humans, and its presence in the gastric epithelium is strongly associated with gastritis, peptic ulcer disease, and gastric cancer. Having evolved in this specific gastric niche for hundreds of thousands of years, this microbe has become dependent on its human host. Bioinformatic analysis reveals that H. pylori has lost several genes involved in the de novo synthesis of purine nucleotides, and without this pathway present, H. pylori must salvage purines from its environment in order to grow. While the presence and abundance of free purines in various mammalian tissues...

14. Identification of a Ligand on the Wip1 Bacteriophage Highly Specific for a Receptor on Bacillus anthracis - Kan, Sherry; Fornelos, Nadine; Schuch, Raymond; Fischetti, Vincent A.
Tectiviridae is a family of tailless bacteriophages with Gram-negative and Gram-positive hosts. The family model PRD1 and its close relatives all infect a broad range of enterobacteria by recognizing a plasmid-encoded conjugal transfer complex as a receptor. In contrast, tectiviruses with Gram-positive hosts are highly specific to only a few hosts within the same bacterial species. The cellular determinants that account for the observed specificity remain unknown. Here we present the genome sequence of Wip1, a tectivirus that infects the pathogen Bacillus anthracis. The Wip1 genome is related to other tectiviruses with Gram-positive hosts, notably, AP50, but displays some interesting...

15. Trapping and Identification of Cellular Substrates of the Staphylococcus aureus ClpC Chaperone - Graham, Justin W.; Lei, Mei G.; Lee, Chia Y.
ClpC is an ATP-dependent Hsp100/Clp chaperone involved in protein quality control in low-GC Gram-positive bacteria. Previously, we found that ClpC affected the expression of a large number of genes, including capsule genes in Staphylococcus aureus. Here we constructed a His-tagged ClpC variant (ClpCtrap) with mutations within the Walker B motifs to identify the direct substrates of ClpC by copurification with ClpCtrap followed by gel electrophoresis combined with liquid chromatography-tandem mass spectrometry proteomics. We identified a total of 103 proteins that are potential substrates of ClpC in strain Newman. The direct protein-protein interaction of ClpC with a subset of the captured...

16. Function of a Glutamine Synthetase-Like Protein in Bacterial Aniline Oxidation via γ-Glutamylanilide - Takeo, Masahiro; Ohara, Akira; Sakae, Shinji; Okamoto, Yasuhiro; Kitamura, Chitoshi; Kato, Dai-ichiro; Negoro, Seiji
Acinetobacter sp. strain YAA has five genes (atdA1 to atdA5) involved in aniline oxidation as a part of the aniline degradation gene cluster. From sequence analysis, the five genes were expected to encode a glutamine synthetase (GS)-like protein (AtdA1), a glutamine amidotransferase-like protein (AtdA2), and an aromatic compound dioxygenase (AtdA3, AtdA4, and AtdA5) (M. Takeo, T. Fujii, and Y. Maeda, J. Ferment. Bioeng. 85:17-24, 1998). A recombinant Pseudomonas strain harboring these five genes quantitatively converted aniline into catechol, demonstrating that catechol is the major oxidation product from aniline. To elucidate the function of the GS-like protein AtdA1 in aniline oxidation,...

17. Identification of the Set of Genes, Including Nonannotated morA, under the Direct Control of ModE in Escherichia coli - Kurata, Tatsuaki; Katayama, Akira; Hiramatsu, Masakazu; Kiguchi, Yuya; Takeuchi, Masamitsu; Watanabe, Tomoyuki; Ogasawara, Hiroshi; Ishihama, Akira; Yamamoto, Kaneyoshi
ModE is the molybdate-sensing transcription regulator that controls the expression of genes related to molybdate homeostasis in Escherichia coli. ModE is activated by binding molybdate and acts as both an activator and a repressor. By genomic systematic evolution of ligands by exponential enrichment (SELEX) screening and promoter reporter assays, we have identified a total of nine operons, including the hitherto identified modA, moaA, dmsA, and napF operons, of which six were activated by ModE and three were repressed. In addition, two promoters were newly identified and direct transcription of novel genes, referred to as morA and morB, located on antisense...

18. Comparative Proteome Analysis of Spontaneous Outer Membrane Vesicles and Purified Outer Membranes of Neisseria meningitidis - Lappann, Martin; Otto, Andreas; Becher, Dörte; Vogel, Ulrich
Outer membrane vesicles (OMVs) of Gram-negative bacteria receive increasing attention because of various biological functions and their use as vaccines. However, the mechanisms of OMV release and selective sorting of proteins into OMVs remain unclear. Comprehensive quantitative proteome comparisons between spontaneous OMVs (SOMVs) and the outer membrane (OM) have not been conducted so far. Here, we established a protocol for metabolic labeling of neisserial proteins with 15N. SOMV and OM proteins labeled with 15N were used as an internal standard for proteomic comparison of the SOMVs and OMs of two different strains. This labeling approach, coupled with high-sensitivity mass spectrometry,...

19. In Vitro Evolution of an Archetypal Enteropathogenic Escherichia coli Strain - Nisa, Shahista; Hazen, Tracy H.; Assatourian, Lillian; Nougayrède, Jean-Philippe; Rasko, David A.; Donnenberg, Michael S.
Enteropathogenic Escherichia coli (EPEC) is a leading cause of infantile diarrhea in developing countries. EPEC strain E2348/69 is used worldwide as a prototype to study EPEC genetics and disease. However, isolates of E2348/69 differ phenotypically, reflecting a history of in vitro selection. To identify the genomic and phenotypic changes in the prototype strain, we sequenced the genome of the nalidixic acid-resistant (Nalr) E2348/69 clone. We also sequenced a recent nleF mutant derived by one-step PCR mutagenesis from the Nalr strain. The sequencing results revealed no unintended changes between the mutant and the parent strain. However, loss of the pE2348-2 plasmid...

20. Suppressor Analysis Reveals a Role for SecY in the SecA2-Dependent Protein Export Pathway of Mycobacteria - Ligon, Lauren S.; Rigel, Nathan W.; Romanchuk, Artur; Jones, Corbin D.; Braunstein, Miriam
All bacteria use the conserved Sec pathway to transport proteins across the cytoplasmic membrane, with the SecA ATPase playing a central role in the process. Mycobacteria are part of a small group of bacteria that have two SecA proteins: the canonical SecA (SecA1) and a second, specialized SecA (SecA2). The SecA2-dependent pathway exports a small subset of proteins and is required for Mycobacterium tuberculosis virulence. The mechanism by which SecA2 drives export of proteins across the cytoplasmic membrane remains poorly understood. Here we performed suppressor analysis on a dominant negative secA2 mutant (secA2 K129R) of the model mycobacterium Mycobacterium smegmatis...

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