PubMed Central (PMC3 - NLM DTD)
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 94,954
Amylocyclicin, a Novel Circular Bacteriocin Produced by Bacillus amyloliquefaciens FZB42 - Scholz, Romy; Vater, Joachim; Budiharjo, Anto; Wang, Zhiyuan; He, Yueqiu; Dietel, Kristin; Schwecke, Torsten; Herfort, Stefanie; Lasch, Peter; Borriss, Rainer
Bacillus amyloliquefaciens FZB42 is a Gram-positive plant growth-promoting bacterium with an impressive capacity to synthesize nonribosomal secondary metabolites with antimicrobial activity. Here we report on a novel circular bacteriocin which is ribosomally synthesized by FZB42. The compound displayed high antibacterial activity against closely related Gram-positive bacteria. Transposon mutagenesis and subsequent site-specific mutagenesis combined with matrix-assisted laser desorption ionization–time of flight mass spectroscopy revealed that a cluster of six genes covering 4,490 bp was responsible for the production, modification, and export of and immunity to an antibacterial compound, here designated amylocyclicin, with a molecular mass of 6,381 Da. Peptide sequencing of...
A Novel ESX-1 Locus Reveals that Surface-Associated ESX-1 Substrates Mediate Virulence in Mycobacterium marinum - Kennedy, George M.; Hooley, Gwendolyn C.; Champion, Matthew M.; Mba Medie, Felix; Champion, Patricia A. DiGiuseppe
EsxA (ESAT-6) and EsxB (CFP-10) are virulence factors exported by the ESX-1 system in mycobacterial pathogens. In Mycobacterium marinum, an established model for ESX-1 secretion in Mycobacterium tuberculosis, genes required for ESX-1 export reside at the extended region of difference 1 (RD1) locus. In this study, a novel locus required for ESX-1 export in M. marinum was identified outside the RD1 locus. An M. marinum strain bearing a transposon-insertion between the MMAR_1663 and MMAR_1664 genes exhibited smooth-colony morphology, was deficient for ESX-1 export, was nonhemolytic, and was attenuated for virulence. Genetic complementation revealed a restoration of colony morphology and a...
The Precarious Prokaryotic Chromosome - Kuzminov, Andrei
Evolutionary selection for optimal genome preservation, replication, and expression should yield similar chromosome organizations in any type of cells. And yet, the chromosome organization is surprisingly different between eukaryotes and prokaryotes. The nuclear versus cytoplasmic accommodation of genetic material accounts for the distinct eukaryotic and prokaryotic modes of genome evolution, but it falls short of explaining the differences in the chromosome organization. I propose that the two distinct ways to organize chromosomes are driven by the differences between the global-consecutive chromosome cycle of eukaryotes and the local-concurrent chromosome cycle of prokaryotes. Specifically, progressive chromosome segregation in prokaryotes demands a single...
All in the Family: Kin Contact Leads to Outer Membrane Exchange - Hartzell, Trish
The ability to recognize related cells in a population can confer evolutionary benefits. For example, some bacteria use contact-dependent inhibition proteins to distinguish kin from nonkin. Kinship recognition is taken to a new level in Myxococcus, which uses the dual-purpose TraA protein for kin recognition and outer membrane and lipoprotein exchange. In this issue of the Journal of Bacteriology, Wei et al. (X. Wei, C. N. Vassallo, D. T. Pathak, D. Wall, J. Bacteriol. 196:1807–1814, 2014) show that Tra-dependent exchange can be uncoupled from outer membrane vesicle/tube formation, reported elsewhere to mediate outer membrane exchange.
Myxobacteria Produce Outer Membrane-Enclosed Tubes in Unstructured Environments - Wei, Xueming; Vassallo, Christopher N.; Pathak, Darshankumar T.; Wall, Daniel
Myxobacteria are social microbes that exhibit complex multicellular behaviors. By use of fluorescent reporters, we show that Myxococcus xanthus isolates produce long narrow filaments that are enclosed by the outer membrane (OM) and contain proteins. We show that these OM tube (OMT) structures are produced at surprisingly high levels when cells are placed in liquid medium or buffer without agitation. OMTs can be long and easily exceed multiple cell lengths. When viewed by transmission electron microscopy, their morphology varies between tubes and chain-like structures. Intermediate-like structures are also found, suggesting that OMTs may transition between these two morphotypes. In support...
Mycobacterium tuberculosis Latin American-Mediterranean Family and Its Sublineages in the Light of Robust Evolutionary Markers - Mokrousov, Igor; Vyazovaya, Anna; Narvskaya, Olga
Mycobacterium tuberculosis has a clonal population structure, and the Latin American-Mediterranean (LAM) family is one of the largest and most widespread within this species, showing evidence for remarkable pathobiology and a confusing phylogeny. Here, we applied robust phylogenetic markers to study the evolution of the LAM family and its major sublineages circulating in Russia and neighboring countries. A total of 250 M. tuberculosis isolates were confirmed to belong to the LAM family based on the analysis of the LAM-specific single-nucleotide polymorphisms (SNPs) in the Rv3062 and Rv0129c genes. At this stage, the family status was rectified for 121 isolates misleadingly...
Outer Membrane Protein OmpW Participates with Small Multidrug Resistance Protein Member EmrE in Quaternary Cationic Compound Efflux - Beketskaia, Maria S.; Bay, Denice C.; Turner, Raymond J.
In Escherichia coli, the small multidrug resistance (SMR) transporter protein EmrE confers host resistance to a broad range of toxic quaternary cation compounds (QCC) via proton motive force in the plasma membrane. Biologically produced QCC also act as EmrE osmoprotectant substrates within the cell and participate in host pH regulation and osmotic tolerance. Although E. coli EmrE is one of the most well-characterized SMR members, it is unclear how the substrates it transports into the periplasm escape across the outer membrane (OM) in Gram-negative bacteria. We tested the hypothesis that E. coli EmrE relies on an unidentified OM protein (OMP)...
Localization of P42 and F1-ATPase α-Subunit Homolog of the Gliding Machinery in Mycoplasma mobile Revealed by Newly Developed Gene Manipulation and Fluorescent Protein Tagging - Tulum, Isil; Yabe, Masaru; Uenoyama, Atsuko; Miyata, Makoto
Mycoplasma mobile has a unique mechanism that enables it to glide on solid surfaces faster than any other gliding mycoplasma. To elucidate the gliding mechanism, we developed a transformation system for M. mobile based on a transposon derived from Tn4001. Modification of the electroporation conditions, outgrowth time, and colony formation from the standard method for Mycoplasma species enabled successful transformation. A fluorescent-protein tagging technique was developed using the enhanced yellow fluorescent protein (EYFP) and applied to two proteins that have been suggested to be involved in the gliding mechanism: P42 (MMOB1050), which is transcribed as continuous mRNA with other proteins...
Biochemical Characterization of a Nitrogen-Type Phosphotransferase System Reveals that Enzyme EINtr Integrates Carbon and Nitrogen Signaling in Sinorhizobium meliloti - Goodwin, Reed A.; Gage, Daniel J.
In Sinorhizobium meliloti, catabolite repression is influenced by a noncanonical nitrogen-type phosphotransferase system (PTSNtr). In this PTSNtr, the protein HPr is phosphorylated on histidine-22 by the enzyme EINtr and the flux of phosphate through this residue onto downstream proteins leads to an increase in succinate-mediated catabolite repression (SMCR). In order to explore the molecular determinants of HPr phosphorylation by EINtr, both proteins were purified and the activity of EINtr was measured. Experimentally determined kinetic parameters of EINtr activity were significantly slower than those determined for the carbohydrate-type EI in Escherichia coli. Enzymatic assays showed that glutamine, a signal of nitrogen...
The KC Channel in the cbb3-Type Respiratory Oxygen Reductase from Rhodobacter capsulatus Is Required for Both Chemical and Pumped Protons - Yıldız, Gülgez Gökçe; Gennis, Robert B.; Daldal, Fevzi; Öztürk, Mehmet
The heme-copper superfamily of proton-pumping respiratory oxygen reductases are classified into three families (A, B, and C families) based on structural and phylogenetic analyses. Most studies have focused on the A family, which includes the eukaryotic mitochondrial cytochrome c oxidase as well as many bacterial homologues. Members of the C family, also called the cbb3-type oxygen reductases, are found only in prokaryotes and are of particular interest because of their presence in a number of human pathogens. All of the heme-copper oxygen reductases require proton-conducting channels to convey chemical protons to the active site for water formation and to convey...
Functional Dissection of Intersubunit Interactions in the EspR Virulence Regulator of Mycobacterium tuberculosis - Blasco, Benjamin; Japaridze, Aleksandre; Stenta, Marco; Wicky, Basile I. M.; Dietler, Giovanni; Dal Peraro, Matteo; Pojer, Florence; Cole, Stewart T.
The nucleoid-associated protein EspR, a chromosome organizer, has pleiotropic effects on expression of genes associated with cell wall function and pathogenesis in Mycobacterium tuberculosis. In particular, EspR binds to several sites upstream of the espACD locus to promote its expression, thereby ensuring full function of the ESX-1 secretion system, a major virulence determinant. The N terminus of EspR contains the helix-turn-helix DNA-binding domain, whereas the C-terminal dimerization domain harbors residues involved in intersubunit interactions. While direct binding to DNA appears to be mediated by an EspR dimer-of-dimers, where two helix-turn-helix motifs remain free for long-range interactions, the mechanism of EspR...
Iron-Regulated Protein HupB of Mycobacterium tuberculosis Positively Regulates Siderophore Biosynthesis and Is Essential for Growth in Macrophages - Pandey, Satya Deo; Choudhury, Mitali; Yousuf, Suhail; Wheeler, Paul R.; Gordon, Stephen V.; Ranjan, Akash; Sritharan, Manjula
Mycobacterium tuberculosis expresses the 28-kDa protein HupB (Rv2986c) and the Fe3+-specific high-affinity siderophores mycobactin and carboxymycobactin upon iron limitation. The objective of this study was to understand the functional role of HupB in iron acquisition. A hupB mutant strain of M. tuberculosis, subjected to growth in low-iron medium (0.02 μg Fe ml−1), showed a marked reduction of both siderophores with low transcript levels of the mbt genes encoding the MB biosynthetic machinery. Complementation of the mutant strain with hupB restored siderophore production to levels comparable to that of the wild type. We demonstrated the binding of HupB to the mbtB...
Identification of a Novel Aminopropyltransferase Involved in the Synthesis of Branched-Chain Polyamines in Hyperthermophiles - Okada, Kazuma; Hidese, Ryota; Fukuda, Wakao; Niitsu, Masaru; Takao, Koichi; Horai, Yuhei; Umezawa, Naoki; Higuchi, Tsunehiko; Oshima, Tairo; Yoshikawa, Yuko; Imanaka, Tadayuki; Fujiwara, Shinsuke
Longer- and/or branched-chain polyamines are unique polycations found in thermophiles. N4-aminopropylspermine is considered a major polyamine in Thermococcus kodakarensis. To determine whether a quaternary branched penta-amine, N4-bis(aminopropyl)spermidine, an isomer of N4-aminopropylspermine, was also present, acid-extracted cytoplasmic polyamines were analyzed by high-pressure liquid chromatography, gas chromatography (HPLC), and gas chromatography-mass spectrometry. N4-bis(aminopropyl)spermidine was an abundant cytoplasmic polyamine in this species. To identify the enzyme that catalyzes N4-bis(aminopropyl)spermidine synthesis, the active fraction was concentrated from the cytoplasm and analyzed by linear ion trap–time of flight mass spectrometry with an electrospray ionization instrument after analysis by the MASCOT database. TK0545, TK0548, TK0967, and...
Analysis of the Loss in Heat and Acid Resistance during Germination of Spores of Bacillus Species - Luu, Stephanie; Setlow, Peter
A major event in the nutrient germination of spores of Bacillus species is release of the spores' large depot of dipicolinic acid (DPA). This event is preceded by both commitment, in which spores continue through germination even if germinants are removed, and loss of spore heat resistance. The latter event is puzzling, since spore heat resistance is due largely to core water content, which does not change until DPA is released during germination. We now find that for spores of two Bacillus species, the early loss in heat resistance during germination is most likely due to release of committed spores'...
Purification and Characterization of Phosphonoglycans from Glycomyces sp. Strain NRRL B-16210 and Stackebrandtia nassauensis NRRL B-16338 - Yu, Xiaomin; Price, Neil P. J.; Evans, Bradley S.; Metcalf, William W.
Two related actinomycetes, Glycomyces sp. strain NRRL B-16210 and Stackebrandtia nassauensis NRRL B-16338, were identified as potential phosphonic acid producers by screening for the gene encoding phosphoenolpyruvate (PEP) mutase, which is required for the biosynthesis of most phosphonates. Using a variety of analytical techniques, both strains were subsequently shown to produce phosphonate-containing exopolysaccharides (EPS), also known as phosphonoglycans. The phosphonoglycans were purified by sequential organic solvent extractions, methanol precipitation, and ultrafiltration. The EPS from the Glycomyces strain has a mass of 40 to 50 kDa and is composed of galactose, xylose, and five distinct partially O-methylated galactose residues. Per-deutero-methylation analysis...
The C-Terminal Part of Microcin B Is Crucial for DNA Gyrase Inhibition and Antibiotic Uptake by Sensitive Cells - Shkundina, Irina; Serebryakova, Marina; Severinov, Konstantin
Microcin B (McB) is a ribosomally synthesized antibacterial peptide. It contains up to nine oxazole and thiazole heterocycles that are introduced posttranslationally and are required for activity. McB inhibits the DNA gyrase, a validated drug target. Previous structure-activity analyses indicated that two fused heterocycles located in the central part of McB are important for antibacterial action and gyrase inhibition. Here, we used site-specific mutagenesis of the McB precursor gene to assess the functional significance of the C-terminal part of McB that is located past the second fused heterocycle and contains two single heterocycles as well as an unmodified four-amino-acid C-terminal...
Diversity of O-Antigen Repeat Unit Structures Can Account for the Substantial Sequence Variation of Wzx Translocases - Hong, Yaoqin; Reeves, Peter R.
The most common system for synthesis of cell surface polysaccharides is the Wzx/Wzy-dependent pathway, which involves synthesis, on the cytoplasmic face of the cell membrane, of repeat units, which are then translocated to the periplasmic face by a Wzx translocase and then polymerized by Wzy to generate the polysaccharide. One such polysaccharide is O antigen, which is incorporated into lipopolysaccharide (LPS). The O antigen is extremely variable, with over 186 forms in Escherichia coli. Wzx proteins are also very diverse, but they have been thought to be specific only for the first sugar of the repeat units. However, recent studies...
Genome-Wide Analysis of Small RNAs Expressed by Yersinia pestis Identifies a Regulator of the Yop-Ysc Type III Secretion System - Schiano, Chelsea A.; Koo, Jovanka T.; Schipma, Matthew J.; Caulfield, Adam J.; Jafari, Nadereh; Lathem, Wyndham W.
Small noncoding RNA (sRNA) molecules are integral components of the regulatory machinery for many bacterial species and are known to posttranscriptionally regulate metabolic and stress-response pathways, quorum sensing, virulence factors, and more. The Yop-Ysc type III secretion system (T3SS) is a critical virulence component for the pathogenic Yersinia species, and the regulation of this system is tightly controlled at each step from transcription to translocation of effectors into host cells. The contribution of sRNAs to the regulation of the T3SS in Yersinia has been largely unstudied, however. Previously, our lab identified a role for the sRNA chaperone protein Hfq in...
The Flagellar Soluble Protein FliK Determines the Minimal Length of the Hook in Salmonella enterica Serovar Typhimurium - Uchida, Kaoru; Aizawa, Shin-Ichi
The length of the flagellar hook is controlled by the soluble protein FliK. FliK is structurally divided into two halves with distinct functions; the N-terminal half determines hook length, while the C-terminal half switches the secretion substrate specificity, consequently terminating hook elongation. FliK properly achieves both functions only when it is secreted. In a previous paper, we showed that a temperature-sensitive flgE mutant of Salmonella enterica serovar Typhimurium, SJW2219, produced basal bodies with short hooks (average length, 25 nm) at 37°C. In this study, we show that the mutant cells grown at 37°C secrete FliK but not flagellin (FliC), indicating...