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Journal of Bacteriology

Birgit M Prüβ
Two-component signaling is a specialized mechanism that bacteria use to respond to changes in their environment. Non-pathogenic strains of E. coli K-12 harbor 30 histidine kinases and 32 response regulators, which form a network of regulation that integrates many other global regulators that do not follow the two-component signaling mechanism, as well as signals from central metabolism. The output of this network is a multitude of phenotypic changes in response to changes in the environment. Among these phenotypic changes, many two-component systems control motility and/or the formation of biofilm, sessile communities of bacteria that form on surfaces...
May 22, 2017: Journal of Bacteriology
Elías J Mongiardini, J Ignacio Quelas, Carolina Dardis, M Julia Althabegoiti, Aníbal R Lodeiro
Bradyrhizobium diazoefficiens, the soybean N2-fixing symbiont, possesses a dual flagellar system comprising a constitutive subpolar flagellum and inducible lateral flagella. Here, we analyzed the genomic organization and biosynthetic regulation of the lateral-flagellar genes. We found that those genes are located in a single genomic cluster, organized in two monocistronic transcriptional units and three operons, one possibly containing an internal transcription start site. Among the monocistronic units is blr6846, homologous to the Class-IB master regulators of flagella synthesis in Brucella melitensis and Ensifer meliloti, and required for the expression of all the lateral-flagellar genes except lafA2, which locus encodes a single lateral flagellin...
May 22, 2017: Journal of Bacteriology
Antonella Succurro, Fiona Wanjiku Moejes, Oliver Ebenhöh
The last few years have seen the advancement of high-throughput experimental techniques produce an extraordinary amount of data. Bioinformatics and statistical analyses have become instrumental to interpreting the information coming from e.g. sequencing data, and often motivate further targeted experiments. The broad discipline of "computational biology" spans far beyond the well-established field of bioinformatics, but it is our impression that more theoretical methods like mathematical models are not yet as well integrated in the research studying microbial interactions...
May 22, 2017: Journal of Bacteriology
Alan Basset, Muriel Herd, Raecliffe Daly, Simon L Dove, Richard Malley
In Streptococcus pneumoniae, the type 1 pilus is involved in many steps of pathogenesis, including adherence to epithelial cells, mediation of inflammation, escape from macrophages, and the formation of biofilms. The type 1 pilus genes are expressed in a bistable fashion with cells switching between ON and OFF expression states. Bistable expression of these genes is due to their control by RlrA, a positive regulator subject to control by a positive feedback loop. The type 1 pilus genes are also thought to be negatively regulated by a large number of repressors...
May 15, 2017: Journal of Bacteriology
Elodie Lesne, Elian Dupré, Camille Locht, Rudy Antoine, Françoise Jacob-Dubuisson
The whooping cough agent, Bordetella pertussis, controls the expression of its large virulence regulon in a coordinated manner through the two-component system BvgAS. BvgS is a dimeric, multi-domain sensor-kinase. Each monomer comprises in succession tandem periplasmic Venus flytrap (VFT) domains, a transmembrane segment, a cytoplasmic Per-ArnT-Sim (PAS) domain, a kinase module and additional phosphorelay domains. BvgS shifts between kinase and phosphatase modes of activity in response to chemical modulators that modify the clamshell motions of the VFT domains...
May 15, 2017: Journal of Bacteriology
James D Chang, Erin E Foster, Aanchal N Thadani, Alejandro J Ramirez, Sung Joon Kim
Oritavancin is a lipoglycopeptide antibiotic that exhibits potent activities against vancomycin-resistant Gram-positive pathogens. Oritavancin differs from vancomycin by a hydrophobic side chain attached to the drug disaccharide, which forms a secondary-binding site to enable oritavancin binding to the cross-linked peptidoglycan in cell wall. The mode of action of secondary-binding site was investigated by measuring the changes in the peptidoglycan composition of Staphylococcus aureus grown in presence of desleucyl-oritavancin at sub-inhibitory concentration using liquid chromatography-mass spectrometry (LC-MS)...
May 15, 2017: Journal of Bacteriology
Smarajit Mondal, Alexander V Yakhnin, Paul Babitzke
The Bacillus subtilis trpEDCFBA operon is regulated by a transcription attenuation mechanism in which tryptophan-activated TRAP binds to the nascent transcript and blocks formation of an antiterminator structure such that formation of an overlapping intrinsic terminator causes termination in the 5' untranslated region (5' UTR). In the absence of bound TRAP the antiterminator forms and transcription continues into the trp genes. RNA polymerase pauses at positions U107 and U144 in the 5' UTR. The general transcription elongation factors NusA and NusG stimulate pausing at both positions...
May 15, 2017: Journal of Bacteriology
B Remes, T Rische-Grahl, K M H Müller, K U Förstner, Y Sung-Huan, L Weber, A Jäger, V Peuser, G Klug
Under unfavorable growth conditions, bacteria enter stationary phase and can maintain cell viability over prolonged periods with no increase in cell number. To get insights into the regulatory mechanisms that allow bacteria to resume growth when conditions become favorable again (outgrowth) we performed global transcriptome analyses at different stages of growth for the alphaproteobacterium Rhodobacter sphaeroides The majority of genes was not differentially expressed across growth phases. After short stationary phase (about 20 h after growth starts to slow down), only 7 % of the genes showed altered expression (fold change of > 1...
May 15, 2017: Journal of Bacteriology
Anna F Wang Erickson, Padraig Deighan, Cinthia P Garcia, Robert O J Weinzierl, Ann Hochschild, Richard Losick
Sigma (σ) factors direct gene transcription by binding to and determining the promoter recognition specificity of RNA polymerase (RNAP) in bacteria. Genes transcribed under the control of alternative sigma factors allow cells to respond to stress and undergo developmental processes such as sporulation in Bacillus subtilis, in which gene expression is controlled by a cascade of alternative sigma factors. Binding of sigma factors to RNA polymerase depends on the coiled-coil (or clamp helices) motif of the β' subunit...
May 15, 2017: Journal of Bacteriology
Paul Babitzke, Michael O'Connor
The canonical translation initiation mechanism involves base pairing between the mRNA and 16S rRNA. However, a variety of identified mechanisms deviate from this conventional route. In this issue of Journal of Bacteriology, Beck and Janssen describe another non-canonical mode of translation initiation. We describe how this process differs from previously reported mechanisms with the hope that it will foster increased awareness of the diversity of regulatory mechanisms that await discovery.
May 8, 2017: Journal of Bacteriology
Brian A Klein, Louis P Cornacchione, Marisha Collins, Michael H Malamy, Margaret J Duncan, Linden T Hu
Cellular pigmentation is an important virulence factor of the oral pathogen Porphyromonas gingivalis Pigmentation has been associated with many bacterial functions including but not limited to: colonization, maintaining a local anaerobic environment by binding oxygen molecules, and defense against reactive oxygen species (ROS) produced by immune cells. Pigmentation-associated loci identified to date have involved lipopolysaccharide, fimbriae and haem acquisition and processing. We utilized a transposon mutant library of P...
May 8, 2017: Journal of Bacteriology
Mengyi Cao, Heidi Goodrich-Blair
In mutually beneficial and pathogenic symbiotic associations, microbes must adapt to the host environment for optimal fitness. Both within an individual host and during transmission between hosts, microbes are exposed to temporal and spatial variation in environmental conditions. The phenomenon of phenotypic variation, in which different subpopulations of cells express distinctive and potentially adaptive characteristics, can contribute to microbial adaptation to a lifestyle that includes rapidly changing environments...
May 8, 2017: Journal of Bacteriology
Heather J Beck, Gary R Janssen
Alternative translation initiation mechanisms, distinct from the Shine-Dalgarno (SD) sequence-dependent mechanism, are more prevalent in bacteria than once anticipated. Translation of Escherichia coliptrB instead requires an AUG triplet at the 5'-terminus of its messenger RNA (mRNA). The 5'-terminal AUG (5'-uAUG) acts as a ribosomal recognition signal to attract ribosomes to the ptrB mRNA rather than functioning as an initiation codon to support translation of an upstream open reading frame. ptrB expression exhibits a stronger dependence on the 5'-uAUG than the predicted SD sequence; however, strengthening the predicted ptrB SD sequence relieves the necessity for the 5'-uAUG...
May 8, 2017: Journal of Bacteriology
Sonia L Bardy, Ariane Briegel, Simon Rainville, Tino Krell
Unraveling the structure and function of two-component and chemotactic signaling along with different aspects related to motility of bacteria and archaea are key research areas in modern microbiology. Escherichia coli is the traditional model organism to study chemotaxis signaling and motility. However, the recent study of a wide range of bacteria and even some archaea with different lifestyles has provided new insight into the eco-physiology of chemotaxis, which is essential for the host establishment of different pathogens or beneficial bacteria...
May 8, 2017: Journal of Bacteriology
Cierra Birch, Madison Davis, Lea Mbengi, Peter Zuber
Bacillus subtilis Spx is a global transcriptional regulator that is conserved among gram-positive bacteria, in which Spx is required for preventing oxidatively induced proteotoxicity. Upon stress induction, Spx engages RNA polymerase (RNAP) through interaction with the C-terminal domain of the rpoA-encoded RNAP α subunit (αCTD). Previous mutational analysis of rpoA revealed that substitutions of Y263 in αCTD severely impaired Spx-activated transcription. Attempts to substitute alanine for αCTD R261, R268, R289, E255, E298 and K294 were unsuccessful, suggesting that these residues are essential...
May 8, 2017: Journal of Bacteriology
Alyssa S Ball, Ryan R Chaparian, Julia C van Kessel
Coordination of group behaviors in bacteria is accomplished via the cell-cell signaling process called quorum sensing. Vibrios have historically been models for studying bacterial communication due to the diverse and remarkable behaviors controlled by quorum sensing in these bacteria, including bioluminescence, type III and type VI secretion, biofilm formation, and motility. Here, we discuss the Vibrio LuxR/HapR family of proteins, the master global transcription factors that direct downstream gene expression in response to changes in cell density...
May 8, 2017: Journal of Bacteriology
Ogun Adebali, Marharyta G Petukh, Alexander O Reznik, Artem V Tishkov, Amit A Upadhyay, Igor B Zhulin
Histidine kinases are key components of regulatory systems that enable bacteria to respond to environmental changes. Two major classes of histidine kinases are recognized on the basis of their modular design: classical (HKI) and chemotaxis-specific (HKII). Recently, a new type of histidine kinases that appeared to have features of both HKI and HKII was identified and termed HKIII; however, the details of HKIII's relationship to other two classes of histidine kinases, their function and evolutionary history remain unknown...
May 8, 2017: Journal of Bacteriology
J Bartoli, L My, Lucid Belmudes, Yohann Couté, J P Viala, E Bouveret
The phospholipid (PL) composition of bacterial membranes varies as a function of growth rate and in response to changes in the environment. While growth adaptation can be explained by biochemical feedbacks in the PL synthesis pathway, recent transcriptome studies have revealed that the expression of PL synthesis genes can also be tuned in response to various stresses. We previously showed that the BasRS two-component pathway controls expression of the diacylglycerol kinase gene dgkA in Escherichia coli (Wahl et al, Mol...
May 8, 2017: Journal of Bacteriology
Sujina Mali, Morgan Mitchell, Spencer Havis, Abiodun Bodunrin, Jonathan Rangel, Gabriella Olson, William R Widger, Steven J Bark
Dormancy is a protective state where diverse bacteria including M. tuberculosis, S. aureus, T. pallidum (syphilis), and B. burgdorferi (Lyme Disease) curtail metabolic activity to survive external stresses including antibiotics. Evidence suggests dormancy consists of a continuum of interrelated states including viable but nonculturable (VBNC) and persistence states. VBNC and persistence contribute to antibiotic tolerance, reemergence from latent infections, and even quorum sensing and biofilm formation. Previous studies indicate that the protein mechanisms regulating persistence and VBNC states are not well understood...
May 8, 2017: Journal of Bacteriology
Xue Liu, Jing-Wen Li, Zhixing Feng, Youfu Luo, Jan-Willem Veening, Jing-Ren Zhang
Reversible or phenotypic tolerance to antibiotics within microbial populations has been implicated in treatment failure of chronic infections and development of persister cells. However, the molecular mechanisms regulating phenotypic drug tolerance are largely unknown. In this study, we identified a four-gene operon in Streptococcus pneumoniae that contributes to phenotypic tolerance to vancomycin (ptv). RNA-Seq, qRT-PCR, and transcriptional luciferase reporter experiments revealed that transcription of the ptv operon (consisting of ptvR, ptvA, ptvB and ptvC) is induced by exposure to vancomycin...
May 8, 2017: Journal of Bacteriology
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