Kooperativer Bibliotheksverbund

Berlin Brandenburg

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  • 1
    In: Molecular Microbiology, August 2010, Vol.77(3), pp.533-536
    Description: Large externalized, repeat‐rich proteins are emerging as important factors in the attachment of bacteria to biotic and abiotic surfaces. An intriguing new study of the plant‐associated terrestrial microbe by Manuel Espinosa‐Urgel's group that is reported in this issue of has revealed that LapF, a huge protein (〉 6000 aa) associated with the cell surface, is required for microcolony assembly from single attached cells, and in turn, formation of biofilms. Mutants defective in exhibit competitive deficiencies in the rhizosphere. On both biotic and abiotic surfaces, these mutants undergo normal irreversible attachment, but cannot advance beyond this point to form multicellular clusters. The phenotype is nutritionally conditional and is only manifested under a subset of growth regimes. Accordingly, gene expression is controlled by the stress‐responsive sigma factor RpoS and is elevated within growing microcolonies on abiotic surfaces and plant tissues. Earlier work had identified the LapA protein, another enormous cell surface protein (〉 8000 aa), as a key requirement for the reversible to irreversible transition during attachment. The current findings support a model in which LapA and LapF act in a relay to drive the stable colonization of surfaces and subsequent assembly of the multicellular structures.
    Keywords: Gene Expression ; Colonization ; Cell Surface ; Rhizosphere ; Biofilms ; Sigma Factor ; Pseudomonas Putida ; Genetics & Taxonomy ; Cell Biology;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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  • 2
    Language: English
    In: Journal of bacteriology, July 2013, Vol.195(13), pp.2947-58
    Description: The ASM 6th Conference on Biofilms was held in Miami, Florida, 29 September to 4 October, 2012. The conference provided an opportunity for the exchange of new findings and ideas with regard to biofilm research. A wide range of findings, spanning applied biology, evolution, ecology, physiology, and molecular biology, were presented at the conference. This review summarizes the presentations with regard to emerging biofilm-related themes.
    Keywords: Biofilms
    ISSN: 00219193
    E-ISSN: 1098-5530
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  • 3
    Language: English
    In: Journal of Bacteriology, July, 2011, Vol.193(13-14), p.3461(12)
    Description: The plant pathogen Agrobacterium tumefaciens encodes predicted iron-responsive regulators, Irr and RirA, that function in several other bacteria to control the response to environmental iron levels. Deletion mutations of irr and rirA, alone and in combination, were evaluated for their impact on cellular iron response. Growth was severely diminished in the [DELTA]irr mutant under iron-limiting conditions, but reversed to wild-type levels in an [DELTA]irr [DELTA]rirA mutant. The level of uncomplexed iron in the [DELTA]irr mutant was decreased, whereas the [DELTA]rirA mutant exhibited elevated iron levels. Sensitivity of the [DELTA]irr and [DELTA]rirA mutants to iron-activated antimicrobial compounds generally reflected their uncomplexed-iron levels. Expression of genes that encode iron uptake systems was decreased in the [DELTA]irr mutant, whereas that of iron utilization genes was increased. Irr function required a trihistidine repeat likely to mediate interactions with heme. Iron uptake genes were derepressed in the [DELTA]rirA mutant. In the [DELTA]irr [DELTA]rirA mutant, iron uptake and utilization genes were derepressed, roughly combining the phenotypes of the single mutants. Siderophore production was elevated in the rirA mutant, but most strongly regulated by an RirA-controiled sigma factor. Expression of rirA itself was regulated by Irr, RirA, and iron availability, in contrast to irr expression, which was relatively stable in the different mutants. These studies suggest that in A. tumefaciens, the Irr protein is most active under low-iron conditions, inhibiting iron utilization and activating iron acquisition, while the RirA protein is active under high-iron conditions, repressing iron uptake. doi:10.1128/JB.00317-11
    Keywords: Agrobacterium Tumefaciens -- Physiological Aspects ; Agrobacterium Tumefaciens -- Genetic Aspects ; Agrobacterium Tumefaciens -- Research ; Iron (Nutrient) -- Physiological Aspects ; Iron (Nutrient) -- Genetic Aspects ; Iron (Nutrient) -- Research
    ISSN: 0021-9193
    Source: Cengage Learning, Inc.
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  • 4
    In: Evolution, June 2012, Vol.66(6), pp.1953-1965
    Description: Cooperative benefits depend on a variety of ecological factors. Many cooperative bacteria increase the population size of their groups by making a public good available. Increased local population size can alleviate the constraints of kin competition on the evolution of cooperation by enhancing the between‐group fitness of cooperators. The cooperative pathogenesis of causes infected plants to exude opines—resources that provide a nearly exclusive source of nutrient for the pathogen. We experimentally demonstrate that opines provide cooperative cells a within‐group fitness advantage over saprophytic agrobacteria. Our results are congruent with a resource–consumer competition model, which predicts that cooperative, virulent agrobacteria are at a competitive disadvantage when opines are unavailable, but have an advantage when opines are available at sufficient levels. This model also predicts that freeloading agrobacteria that catabolize opines but cannot infect plants competitively displace the cooperative pathogen from all environments. However, we show that these cooperative public goods also promote increased local population size. A model built from the Price Equation shows that this effect on group size can contribute to the persistence of cooperative pathogenesis despite inherent kin competition for the benefits of pathogenesis.
    Keywords: Agrobacterium Tumefaciens ; Greenbeard ; Kin Competition ; Multilevel Selection ; Population Size
    ISSN: 0014-3820
    E-ISSN: 1558-5646
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  • 5
    Language: English
    In: Chemical reviews, 12 January 2011, Vol.111(1), pp.1-3
    Keywords: Quorum Sensing ; Bacteria -- Metabolism
    ISSN: 00092665
    E-ISSN: 1520-6890
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  • 6
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States, Jan 31, 2012, Vol.109(5), p.1697(5)
    Description: Elongation of many rod-shaped bacteria occurs by peptidoglycan synthesis at discrete foci along the sidewall of the cells. However, within the Rhizobiales, there are many budding bacteria, in which new cell growth is constrained to a specific region. The phylogeny of the Rhizobiales indicates that this mode of zonal growth may be ancestral. We demonstrate that the rod-shaped bacterium Agrobacterium tumefaciens grows unidirectionally from the new pole generated after cell division and has an atypical peptidoglycan composition. Polar growth occurs under ali conditions tested, including when cells are attached to a plant root and under conditions that induce virulence. Finally, we show that polar growth also occurs in the closely related bacteria Sinorhizobium meliloti, Brucella abortus, and Ochrobactrum anthropi. We find that unipolar growth is an ancestral and conserved trait among the Rhizobiales, which includes important mutualists and pathogens of plants and animals. cell wall morphogenesis | cell elongation-division cycle doi: 10.1073/pnas.1114476109
    Keywords: Proteobacteria -- Physiological Aspects ; Proteobacteria -- Growth ; Peptidoglycans -- Physiological Aspects ; Morphology (Biology) -- Research
    ISSN: 0027-8424
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Journal of Bacteriology, Sept, 2011, Vol.193(17-18), p.5011(2)
    Description: Ruegeria sp. strain KLH11, isolated from the marine sponge Mycale laxissima, produces a complex profile of N-acylhomoserine lactone quorum-sensing (QS) molecules. The genome sequence provides insights into the genetic potential of KLH11 to maintain complex QS systems, and this is the first genome report of a cultivated symbiont from a marine sponge. doi: 10.1128/JB.05556-11
    Keywords: Bacterial Genetics -- Research ; Genomics -- Research ; Proteobacteria -- Physiological Aspects ; Proteobacteria -- Genetic Aspects ; Sponges (Animals) -- Physiological Aspects ; Lactones -- Physiological Aspects ; Lactones -- Genetic Aspects ; Quorum Sensing -- Research
    ISSN: 0021-9193
    Source: Cengage Learning, Inc.
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  • 8
    In: PLoS ONE, 2013, Vol.8(2)
    Description: The α-Proteobacterium Agrobacterium tumefaciens has proteins homologous to known regulators that govern cell division and development in Caulobacter crescentus , many of which are also conserved among diverse α-Proteobacteria. In light of recent work demonstrating similarity between the division cycle of C. crescentus and that of A. tumefaciens , the functional conservation for this presumptive control pathway was examined. In C. crescentus the CtrA response regulator serves as the master regulator of cell cycle progression and cell division. CtrA activity is controlled by an integrated pair of multi-component phosphorelays: PleC/DivJ-DivK and CckA-ChpT-CtrA. Although several of the conserved orthologues appear to be essential in A. tumefaciens , deletions in pleC or divK were isolated and resulted in cell division defects, diminished swimming motility, and a decrease in biofilm formation. A. tumefaciens also has two additional p leC/ d ivJ h omologue s ensor kinases called pdhS1 and pdhS2 , absent in C. crescentus . Deletion of pdhS1 phenocopied the Δ pleC and Δ divK mutants. Cells lacking pdhS2 morphologically resembled wild-type bacteria, but were decreased in swimming motility and elevated for biofilm formation, suggesting that pdhS2 may serve to regulate the motile to non-motile switch in A. tumefaciens. Genetic analysis suggests that the PleC/DivJ-DivK and CckA-ChpT-CtrA phosphorelays in A. tumefaciens are vertically-integrated, as in C. crescentus . A gain-of-function mutation in CckA (Y674D) was identified as a spontaneous suppressor of the Δ pleC motility phenotype. Thus, although the core architecture of the A. tumefaciens pathway resembles that of C. crescentus there are specific differences including additional regulators, divergent pathway architecture, and distinct target functions.
    Keywords: Research Article ; Biology
    E-ISSN: 1932-6203
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  • 9
    Language: English
    In: Journal of bacteriology, 15 August 2014, Vol.196(16), pp.2979-88
    Description: Agrobacterium tumefaciens can adhere to plant tissues and abiotic surfaces and forms biofilms. Cell surface appendages called pili play an important role in adhesion and biofilm formation in diverse bacterial systems. The A. tumefaciens C58 genome sequence revealed the presence of the ctpABCDEFGHI genes (cluster of type IV pili; Atu0216 to Atu0224), homologous to tad-type pilus systems from several bacteria, including Aggregatibacter actinomycetemcomitans and Caulobacter crescentus. These systems fall into the type IVb pilus group, which can function in bacterial adhesion. Transmission electron microscopy of A. tumefaciens revealed the presence of filaments, significantly thinner than flagella and often bundled, associated with cell surfaces and shed into the external milieu. In-frame deletion mutations of all of the ctp genes, with the exception of ctpF, resulted in nonpiliated derivatives. Mutations in ctpA (a pilin homologue), ctpB, and ctpG decreased early attachment and biofilm formation. The adherence of the ctpA mutant could be restored by ectopic expression of the paralogous pilA gene. The ΔctpA ΔpilA double pilin mutant displayed a diminished biovolume and lower biofilm height than the wild type under flowing conditions. Surprisingly, however, the ctpCD, ctpE, ctpF, ctpH, and ctpI mutants formed normal biofilms and showed enhanced reversible attachment. In-frame deletion of the ctpA pilin gene in the ctpCD, ctpE, ctpF, ctpH, and ctpI mutants caused the same attachment-deficient phenotype as the ctpA single mutant. Collectively, these findings indicate that the ctp locus is involved in pilus assembly and that nonpiliated mutants, which retain the CtpA pilin, are proficient in attachment and adherence.
    Keywords: Bacterial Adhesion ; Multigene Family ; Agrobacterium Tumefaciens -- Genetics ; Fimbriae, Bacterial -- Genetics
    ISSN: 00219193
    E-ISSN: 1098-5530
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  • 10
    In: Proceedings of the Royal Society B, 2012, Vol.279(1734), pp.1691-1699
    Description: Harbouring a plasmid often imposes a fitness cost on the bacterial host. Motivated by implications for public health, the majority of studies on plasmid cost are focused on elements that impart antibiotic resistance. Plasmids, however, can provide a wide range of ecologically important phenotypes to their bacterial hosts—such as virulence, specialized catabolism and metal resistance. The Agrobacterium tumefaciens tumour-inducing (Ti) plasmid confers both the ability to infect dicotyledonous plants and to catabolize the metabolites that plants produce as a result of being infected. We demonstrate that this virulence and catabolic plasmid imposes a measurable fitness cost on host cells under resource-limiting, but not resource replete, environmental conditions. Additionally, we show that the expression of Ti-plasmid-borne pathogenesis genes necessary to initiate cooperative pathogenesis is extremely costly to the host cell. The benefits of agrobacterial pathogenesis stem from the catabolism of public goods produced by infected host plants. Thus, the virulence-plasmid-dependent costs we demonstrate constitute costs of cooperation typically associated with the ability to garner the benefits of cooperation. Interestingly, genotypes that harbour derived opine catabolic plasmids minimize this trade-off, and are thus able to freeload upon the pathogenesis initiated by other individuals.
    Keywords: Research articles
    ISSN: 0962-8452
    E-ISSN: 1471-2945
    E-ISSN: 14712954
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