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Journal of Bacteriology

Jonathan B Lynch, Rosanna A Alegado
Outer membrane vesicles (OMVs) are proteoliposome nanoparticles ubiquitously produced by Gram-negative bacteria. Typically bearing similar composition to the outer membrane and periplasm of the cells from which they are derived, OMVs package an array of proteins, lipids, and nucleic acids. Once considered inconsequential byproducts of bacterial growth, OMVs have since been demonstrated to mediate cellular stress relief, promote horizontal gene transfer and antimicrobial activity, and elicit metazoan inflammation...
April 17, 2017: Journal of Bacteriology
George C diCenzo, Harsh Sharthiya, Anish Nanda, Maryam Zamani, Turlough M Finan
Maintenance of cellular phosphate homeostasis is essential for cellular life. The PhoU protein has emerged as a key regulator of this process in bacteria and it is suggested to modulate phosphate import by PstSCAB and control activation of the phosphate limitation response by the PhoR-PhoB two-component system. However, a proper understanding of PhoU has remained elusive due to numerous complications of mutating phoU, including loss of viability and genetic instability of the mutants. Here, we developed two sets of strains of Sinorhizobium meliloti that overcame these limitations and allowed for a more detailed and comprehensive analysis of the biological and molecular activities of PhoU...
April 17, 2017: Journal of Bacteriology
Jessica M Gullett, Amber Bible, Gladys Alexandre
Chemotaxis is the movement of cells in response to gradients of diverse chemical cues. Motile bacteria utilize a conserved chemotaxis signal transduction system to bias their motility and navigate through a gradient. A central regulator of chemotaxis is the histidine kinase, CheA. This cytoplasmic protein interacts with membrane-bound receptors, which assemble into large polar arrays, to propagate the signal. In the alphaproteobacterium, Azospirillum brasilense, Che1 controls transient increases in swimming speed during chemotaxis, but it also biases the cell length at division...
April 17, 2017: Journal of Bacteriology
Brett W Burkhart, Lubomira Cubonova, Margaret R Heider, Zvi Kelman, John N Reeve, Thomas J Santangelo
Many aspects of and factors required for DNA replication are conserved across all three Domains of life but there are some significant differences surrounding lagging strand synthesis. In Archaea, a 5' to 3' exonuclease, related to both bacterial RecJ and eukaryotic Cdc45, that associates with the replisome specifically through interactions with GINS, was identified and designated GAN (for GINS-associated nuclease). Despite the presence of a well-characterized flap endonuclease (Fen1), it was hypothesized that GAN might participate in primer removal during Okazaki fragment maturation and, as a Cdc45 homologue, GAN might also be a structural component of an archaeal CMG (Cdc45, MCM, GINS) replication complex...
April 17, 2017: Journal of Bacteriology
Erin J Breland, Ellisa W Zhang, Tomas Bermudez, Charles R Martinez, Maria Hadjifrangiskou
Two-component systems are prototypically comprised of a histidine kinase (sensor) and a response regulator (responder). The sensor kinases auto-phosphorylate at a conserved histidine residue, acting as a phospho-donor for subsequent phosphotransfer to and activation of a cognate response regulator. In rare cases, the histidine residue is also essential for response regulator de-phosphorylation via a reverse-phosphotransfer reaction. In this work, we present an example of a kinase that relies on reverse-phosphotransfer to catalyze the de-phosphorylation of its cognate partner...
April 10, 2017: Journal of Bacteriology
Angel A Aguirre, Alexandre M Vicente, Steven W Hardwick, Daniela M Alvelos, Ricardo R Mazzon, Ben F Luisi, Marilis V Marques
In diverse bacterial lineages, multi-enzyme assemblies have evolved that are central elements of RNA metabolism and RNA-mediated regulation. The aquatic, Gram-negative bacteria Caulobacter crescentus, which has been a model system for studying the bacterial cell cycle, has an RNA degradosome assembly that is formed by the endoribonuclease RNase E and includes the DEAD-box RNA helicase RhlB. Immunoprecipitations of extracts from cells expressing an epitope-tagged RNase E reveal that RhlE, another member of the DEAD-box helicase family, associates with the degradosome at temperatures below the optimum for growth...
April 10, 2017: Journal of Bacteriology
Karthik R Chamakura, Jennifer S Tran, Ry Young
The L protein of the ssRNA phage MS2 causes lysis of E. coli without inducing a bacteriolytic activity or inhibiting net peptidoglycan (PG) synthesis. To find host genes required for L-mediated lysis, spontaneous Ill ( insensitivity to Llysis) mutants were selected as survivors of L expression and shown to have a missense change of the highly-conserved proline (P330Q) in the C-terminal domain of DnaJ. In the dnaJP330Q host, L-mediated lysis is completely blocked at 30°C without affecting the intracellular levels of L...
April 10, 2017: Journal of Bacteriology
Atsushi Yahashiri, Matthew A Jorgenson, David S Weiss
Sporulation-related repeat (SPOR) domains are small peptidoglycan (PG) binding domains found in thousands of bacterial proteins. The name "SPOR" domain stems from the fact that several early examples came from proteins involved in sporulation, but SPOR domain proteins are quite diverse and contribute to a variety of processes that involve remodelling of the PG sacculus, especially cell division. SPOR domains target proteins to the division site by binding to regions of PG devoid of stem peptides ("denuded" glycans), which in turn are enriched in septal PG by the intense, localized activity of cell wall amidases involved in daughter cell separation...
April 10, 2017: Journal of Bacteriology
Melissa Illingworth, Anna J Hooppaw, Lu Ruan, Derek J Fisher, Lingling Chen
Chaperonins are essential for cellular growth under normal and stressful conditions and consequently represent one of the most conserved and ancient protein classes. The paradigm Escherichia coli chaperonin, EcGroEL, and its cochaperonin, EcGroES, assist folding of proteins via an ATP-dependent mechanism. In addition to the presence of groEL and groES homologs, groEL paralogs are found in many bacteria, including pathogens, and have evolved poorly understood species-specific functions. Chlamydia spp., which are obligate intracellular bacteria, have reduced genomes that nonetheless encode three groEL genes, ChgroEL, ChgroEL2 and ChgroEL3 We hypothesized that ChGroEL is the bona-fide chaperonin, while the paralogs perform novel, Chlamydia-specific functions...
April 10, 2017: Journal of Bacteriology
Surashree S Kulkarni, Yongtao Zhu, Colton J Brendel, Mark J McBride
Flavobacterium johnsoniae and many related bacteria secrete proteins across the outer membrane using the type IX secretion system (T9SS). Proteins secreted by T9SSs have amino-terminal signal peptides for export across the cytoplasmic membrane by the Sec system and carboxy-terminal domains (CTDs) targeting them for secretion across the outer membrane by the T9SS. Most but not all T9SS CTDs belong to family TIGR04183 (type-A CTDs). We functionally characterized diverse CTDs for secretion by the F. johnsoniae T9SS...
April 10, 2017: Journal of Bacteriology
Steven L Distelhorst, Dominika A Jurkovic, Jian Shi, Grant J Jensen, Mitchell F Balish
Although mycoplasmas have small genomes, many of them, including the HIV-associated opportunist Mycoplasma penetrans, construct a polar attachment organelle (AO) used for both adherence to host cells and gliding motility. However, the irregular phylogenetic distribution of similar structures within the mycoplasmas as well as compositional and ultrastructural differences among these AOs suggest that AOs have arisen several times by convergent evolution. We investigated the ultrastructure and protein composition of the cytoskeleton-like material of the M...
April 3, 2017: Journal of Bacteriology
Hervé Nicoloff, Saumya Gopalkrishnan, Sarah E Ades
The alternative sigma factor σ(E) is a key component of the Escherichia coli response to cell envelope stress and is required for viability even in the absence of stress. σ(E) activity increases during entry into stationary phase suggesting an important role for σ(E) when nutrients are limiting. Elevated σ(E) activity has been proposed to activate a pathway leading to lysis of non-culturable cells that accumulate during early stationary phase. To better understand σ(E)-directed cell lysis and the role of σ(E) in stationary phase, we investigated the effects of elevated σ(E) activity in cultures grown for ten days...
April 3, 2017: Journal of Bacteriology
Ashley C Bono, Christine E Hartman, Sina Solaimanpour, Hao Tong, Steffen Porwollik, Michael McClelland, Jonathan G Frye, Jan Mrázek, Anna C Karls
The variable sigma (σ) subunit of the bacterial RNA polymerase (RNAP) holoenzyme, which is responsible for promoter specificity and open complex formation, plays a strategic role in the response to environmental changes. S Typhimurium utilizes the housekeeping σ(70) and five alternative sigma factors, including σ(54) The σ(54)-RNAP differs from other σ-RNAP holoenzymes in that it forms a stable closed complex with the promoter and requires ATP hydrolysis by an activated cognate bacterial enhancer binding protein (bEBP) to transition to open complex and initiate transcription...
April 3, 2017: Journal of Bacteriology
Mark Itsko, Roel M Schaaper
dGTP starvation, a newly discovered phenomenon in which E. coli cells are starved specifically for the DNA precursor dGTP, leads to impaired growth and, ultimately, cell death. Phenomenologically, it represents an example of nutritionally-induced unbalanced growth: cell mass amplifies normally as dictated by the nutritional status of the medium, but DNA content growth is specifically impaired. The other known example of such a condition, Thymineless Death (TLD), involves starvation for the DNA precursor dTTP, which has found important chemotherapeutic applications...
April 3, 2017: Journal of Bacteriology
Keith E Weaver, Yuqing Chen, Elly M Miiller, Jake N Johnson, Alex A Dangler, Dawn A Manias, Aaron M Clem, Daniel J Schjodt, Gary M Dunny
Tools for regulated gene expression in E. faecalis are extremely limited. In this study we describe the construction of an expression vector for E. faecalis, designated pCIE, utilizing the PQ pheromone-responsive promoter of plasmid pCF10. We demonstrate that this promoter is tightly repressed, responds to nanogram quantities of the peptide pheromone, and has a large dynamic range. To demonstrate its utility, the promoter was used to control expression of the toxic peptides of two par family toxin-antitoxin loci present in E...
March 27, 2017: Journal of Bacteriology
Mark J Buttner
The survival strategy of Actinoplanes is fascinating from an evolutionary perspective, combining a short motile phase in an otherwise non-motile, filamentous life cycle, and the somewhat paradoxical concept of spores - normally thought of as a resting stage - that swim. In the first paper to report a molecular genetic analysis of development in Actinoplanes, the authors identify a key regulator of the entry into development.
March 27, 2017: Journal of Bacteriology
Nana Y D Ankrah, Junbo Luan, Angela E Douglas
An important factor determining the impact of microbial symbionts on their animal host is the balance between the cost of nutrients consumed by the symbionts and benefit of nutrients released back to the host, but the quantitative significance of nutrient exchange in symbioses involving multiple microbial partners has rarely been addressed. In this study on the association between two intracellular bacterial symbionts, Portiera aleyrodidarum and Hamiltonella defensa, and their animal host, the whitefly Bemisia tabaci, we apply metabolic modeling to investigate host-symbiont nutrient exchange...
March 27, 2017: Journal of Bacteriology
Eric D Peng, Shelley M Payne
Vibrio cholerae is the causative agent of the severe diarrheal disease cholera. V. cholerae thrives within the human host where it replicates to high numbers but also persists within the aquatic environments of ocean and brackish water. To survive within these nutritionally diverse environments, V. cholerae must encode the necessary tools to acquire the essential nutrient iron in all forms it may encounter. A prior study of systems involved in iron transport in V. cholerae revealed the existence of vciB which, while unable to directly transport iron, stimulates the transport of iron through ferrous (Fe(2+)) iron transport systems...
March 27, 2017: Journal of Bacteriology
Yoshihiro Mouri, Kenji Konishi, Azusa Fujita, Takeaki Tezuka, Yasuo Ohnishi
The rare actinomycete Actinoplanes missouriensis forms sporangia, including hundreds of flagellated spores that start swimming as zoospores after their release. Under conditions suitable for vegetative growth, zoospores stop swimming and germinate. A comparative proteome analysis between zoospores and germinating cells identified 15 proteins that were produced in larger amounts in germinating cells. They include an orthologue of BldD (AmBldD), which is a transcriptional regulator involved in morphological development and secondary metabolism in Streptomyces AmBldD was detected in mycelia during vegetative growth but was barely detected in mycelia during the sporangium-forming phase, in spite of the constant transcription of AmbldD throughout growth...
March 27, 2017: Journal of Bacteriology
Min-Hyung Ryu, Anastasia Fomicheva, Oleg V Moskvin, Mark Gomelsky
Many aspects of bacterial physiology and behavior including motility, surface attachment, and cell cycle, are controlled by the c-di-GMP-dependent signaling pathways on the scale of seconds-to-minutes. Interrogation of such processes in real time requires tools for introducing rapid and reversible changes in intracellular c-di-GMP levels. Inducing expression of genes encoding c-di-GMP synthetic (diguanylate cyclases) and degrading (c-di-GMP phosphodiesterase) enzymes by chemicals may not provide adequate temporal control...
March 20, 2017: Journal of Bacteriology
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