3,140 research outputs found
The molecular function of SwrA: an auxiliary factor modulating DegU transcriptional activity
No full textWe recently demonstrated that the main fla/che promoter PA(fla/che) can be bound by the phosphorylated form of DegU (DegU~P) with two opposite outcomes: complete repression if DegU~P alone is bound to PA(fla/che) DNA; transcriptional stimulation if DNA is bound by DegU~P complexed with SwrA.
Thus SwrA, which is necessary for swarming motility, constitutes an auxiliary factor that modulates the transcriptional activity of the response regulator DegU turning it from a repressor into an activator of PA(fla/che). Evidences indicate that SwrA might modulate other DegU~P-regulated promoters.
Also, we demonstrated that DegU32(Hy) is a mutant protein unable to functionally interact with SwrA at the fla/che promoter; the phenotype of degU32(Hy) strains differs from that of the wild type DegU~P and we suggest the use of degS200(Hy) mutant strains for studies aimed at analyzing the effect of the level of DegU phosphorylation.
SwrA is coded by a gene containing a slippery poly-adenine tract that allows phase variations between a functional and a non-functional allelic state.
In swrA+ cells (typically in undomesticated strains) fla/che transcription oscillates from the basal/medium level to the activated state that is required for swarming. When swrA is in the non-functional form (e.g. in the 168 laboratory strain) fla/che transcription can oscillate between a repressed state in which no flagella are made and a basal/medium level of transcription sufficient for a limited swimming motility. While in both swrA- and swrA+ strains oscillations depend on phosphorylation of DegU mediated by environmental stimuli, in swrA- cells the secondary fla/che promoter PD3(fla/che) plays an important role that might constitute the bistable switch acting on motility
Swarming and poly-gamma-glutamate synthesis depend on the synergic action of SwrAA and DegU in Bacillus subtilis
No full textIsogenic populations of Bacillus subtilis are multicellular communities consisting of distinct differentiated cell types and the two component system DegS-DegU has a central role in the control of single cell fates. The level of DegU phosphorylation attained inside each cell is one of the main parameters used to select specific cell fates but is not the only parameter that triggers a particular genetic programme. In laboratory strains, cooperativity between DegU and SwrAA has been observed in motility: a wild-type copy of the gene (swrAA+) confers a full swimming capacity and the ability to swarm on semi-solid surfaces when DegU is present but it does not show any motility advantage if the two component system DegS/U is deleted (1).
We will show that the synergic action of DegU and SwrAA is a conserved “modus operandi” since it is also observed in the production of poly-gamma-glutamic acid (gamma-PGA), an extracellular anionic polymer composed of thousands of glutamic acid residues linked by gamma-glutamyl bonds, produced and secreted by Bacilli. Domesticated B. subtilis strains synthesize gamma-PGA if they carry a degQH (2) or a degU32(Hy) / degS200(Hy) mutation and the wild type swrAA allele. These data indicate that the activation of the biosynthetic pgs operon is dependent on the co-presence of a high level of DegU~P and SwrAA. The presence of either SwrAA or DegU~P alone has only a marginal effect on gamma-PGA production and pgs operon transcription. The effect of SwrAA and DegU~P is cooperative rather than additive. Motility is not involved in gamma-PGA production since a sigD null mutation or a large deletion in the main flagellar operon (fla/che) do not affect gamma-PGA synthesis in degU32(Hy) swrAA+ strains. Moreover, a fla/che promoter up-mutation, that allows swarming and full swimming motilities in a degU32(Hy) swrAA- strain, does not confer the ability to produce gamma-PGA.
Activation of gamma-PGA synthesis is therefore a motility-independent phenotype in which SwrAA and DegU~P display a cooperative effect.
1) Calvio et al., 2008. J Bacteriol 190:5720-28.
2) Stanley NR and Lazazzera BA, 2005. Mol Microbiol 57:1143-
Poly-gamma-glutamate production in Bacillus subtilis
No full textPoly-gamma-glutamic acid (gamma-PGA) is an anionic polymer of increasing industrial interest, composed of thousands of glutamic acid residues linked by gamma-glutamyl bonds. Secretion of the polymer into the medium confers a mucoid colony morphology to the Bacillus producer strains grown on LB agar plates.
Although Bacillus subtilis possesses the functional biosynthetic pgs operon, containing four genes, laboratory strains do not have the ability to produce the polymer because pgs transcription is not active.
We dissected the genetic elements involved in the conversion of laboratory non-producer strains into gamma-PGA producers and established that the synergic action of two gene products is required. The co-presence of the wild-type swrAA allele, a gene involved in swarming motility, and the hyperphosphorylated form of the transcriptional factor degU, belonging to the two-component system degS/degU, is sufficient to drive pgs transcription and gamma-PGA production
Transcriptional autoregulation of swrAA, a gene involved in Bacillus subtilis motility
No full textThe swrAA gene, required for swarming migration in B. subtilis, is involved in transcriptional regulation of the fla/che operon which contains the genes necessary for flagellum biosynthesis and chemotaxis and the gene coding for the alternative sigma factor SigD. Nevertheless SwrAA does not bear resemblance to DNA binding proteins nor does it show any particular feature by in silico analysis.
In order to gain insight into its biological role we studied its expression profile in relationship with swarming and swimming motility.
We demonstrate that transcription of swrAA is driven by two promoters: a sigD-dependent promoter, active during growth in liquid LB medium, and a putative sigA-dependent promoter, triggered by the phosphorylated form of the two-component response regulator DegU and active during swarming migration.
Our data indicate that DegU is necessary not only for swarming (2, 3), but also for swimming and this requirement is independent from swrAA transcription, since SwrAA over-expression does not restore motility in strains carrying a degU deletion, suggesting that DegU concurs with SwrAA to achieve complete motility in B. subtilis
A imagem de Alessandro Baricco no Brasil
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Estudos da Tradução, Florianópolis, 2013.Com a intenção de delinear o modo pelo qual o escritor italiano Alessandro Baricco se inseriu no sistema literário brasileiro e os caminhos percorridos pelos seus livros traduzidos, esta dissertação dá voz às experiências tradutórias de seus tradutores. A inserção de Bariccono Brasil tem seu início em 1997, através de uma proposição da Profa. Dra. Roberta Barni à editora Iluminuras da tradução de Oceano Mare. A partir daí, outras sete obras foram publicadas no Brasil, sendo três delas traduzidas por Roberta Barni e as outras quatro por quatro tradutores diferentes. De um lado, considera-se o tradutor como figura principal namediação entre culturas, e, de outro, se analisa a realidade desta figuradentro do sistema literário, sua invisibilidade, seus limites e o exercíciode sua profissão. A pesquisa conta, ainda, com críticas e resenhas referentes ao autor italiano publicadas em jornais consagrados no Brasil, considerando estas como parte constituinte da imagem de Baricco refletida em território nacional. Abstract : Intending to delineate the way the Italian writer Alessandro Baricco has been inserted in the Brazilian literary system and the paths his translated books have followed, this thesis gives voice to the translating experiences of his translators. Baricco's insertion in Brazil began in 1997, through a personal project of Dr. Roberta Barni, with her translation of Oceano Mare. Since then, seven other of his works have been published in Brazil, three of which were translated by Roberta Barni and the other four by four different translators. On the one hand,the translator is considered as the main figure in mediation betweencultures and, on the other, this figure's reality is analyzed within theliterary system: its invisibility, its limits and its professional practice. Criticisms and reviews of this Italian author published in well established Brazilian newspapers are also considered, with the understanding that they are part of Baricco's image reflected here
SwrAA activates poly-gamma-glutamate synthesis inaddition to swarming in Bacillus subtilis
No full textPoly-gamma-glutamic acid (γ-PGA) is an extracellular polymer produced by various strains of Bacillus. Ιt was first described as the component of the capsule in B. anthracis, where it plays a relevant role in virulence. γ-PGA is also a distinctive component of “natto”, a Japanese traditional food consisting of soybean fermented by B. subtilis (natto). Domesticated B. subtilis strains do not synthesize γ-PGA although they possess the functional biosynthetic pgs operon. In the present work we explore the correlation between the genetic determinants, swrAA and degU, which allow a derivative of the domestic strain JH642 to display a mucoid colony morphology on LB agar plates due to the production of γ-PGA. Full activation of the pgs operon requires the co-presence of SwrAA and the phosphorylated form of DegU (DegU~P). The presence of either DegU~P or SwrAA alone has only marginal effects on pgs operon transcription and γ-PGA production.
Although SwrAA was identified as necessary for swarming and full swimming motility together with DegU, we show that motility is not involved in γ-PGA production. Activation of γ-PGA synthesis is therefore a motility-independent phenotype in which SwrAA and DegU~P display a cooperative effect
An Auto-Regulatory Loop Governing Motility in Bacillus subtilis
No full textWe will show that transcription of swrAA, the gene required for swarming migration in B. subtilis, is driven by two promoters: a sigD-dependent promoter, active during liquid growth, and a putative sigA-regulated promoter, active in the presence of the phosphorylated form of the response regulator DegU, and in swarming. Since sigD transcription is enhanced by SwrAA (Kearns and Losick, 2005), the finding that swrAA is, in turn, sigD-dependent, delineates the existence of a positive feed-back loop, one possible mechanism to set up bistability.
We will also demonstrate that the positive action played by SwrAA is prevented in strains carrying a deletion of the two component system degS-degU, and this effect is independent from swrAA transcription. As seen by other authors (Verhamme et al., 2007; Kobayashi, 2007), degU is necessary for swarming; however, we will show that also the positive effect of SwrAA on swimming motility is lost in delta-degU strains.
The epistatic effect of degU on swrAA points to a cooperation of the two gene products in the pathway leading to Bacillus motility. This effect might not be unique, as also the activation of the pgs operon, driving the synthesis of gamma-poly-glutamic acid, depends on the concerted action of DegU-P and SwrAA
DNA extraction from soil: comparison of different methods using spore-forming bacteria and the swrAA gene as indicators
Full text linkSoil microcosms seeded with spores of a tracer organism (Bacillus subtilis strain PB5332) were used to test five different
DNA extraction protocols hereby indicated as A, B, C, D and E. The representativity of DNA samples obtained from each procedure was
evaluated by PCR amplification of the swrAA gene, unique to PB5332 strain, followed by Southern hybridization with a gene-specific
probe. A significant improvement of DNA extraction from spores was obtained using grinding under liquid N2 associated with sodiumdodecyl
sulphate (SDS)-based lysis in presence of 1% hexadecyltrimethylammonium bromide (CTAB; protocol C). The same procedure
was tested on soil samples from two distinct greenhouse trials carried out with genetically modified white poplars (Populus alba L.)
expressing the StSy gene for resveratrol production and the bar gene for Basta�� tolerance, respectively. The representativity of DNA
samples recovered from the greenhouse soil was assessed using three spore-forming bacteria (SFB) as tracer organisms. The tracers
(SFB-1, SFB-2 and SFB-3) were previously isolated from the same trials classified as members of the genus Bacillus. All the tested
DNA samples produced the expected amplification products, indicating the presence at the soil level of the tracers and confirming the
reliability of the optimized DNA extraction protocol
An Event and Service Mesh Architecture Supporting Service Integration in Society 5.0 enabled Smart Cities
Full text linkSociety 5.0 envisions a more resilient, sustainable, and human-centered society fostered by ever-evolving cooperation and knowledge sharing among the many digital systems already shaping our daily lives. However, the current state of smart cities often consists of siloed systems, with different actors and stakeholders managing their services and assets independently. This phenomenon is evident in both technological and operational domains, posing challenges to seamless collaboration. In this context, new cloud computing models and technologies like event and service mesh promise to reduce the burden associated with the development and integration of solutions. In the attempt to pave the way for more integrated IT environments, we propose a practical architecture that combines service and event mesh technologies, enabling the seamless exploitation of service invocation and composition based on event distribution and direct service calls. Our proposal allows applications to remain transparent of the underlying technology, facilitating various optimizations on the network and management plane, necessary to meet the diverse operational requirements of complex and heterogeneous applications. We validate our proposal in a real-use case scenario implementation, discussing the tradeoffs that emerge
A QoS-Aware Data Distribution Platform for Edge-Based Vehicular Digital Twins in Smart Cities
No full textDigital Twins (DTs) are emerging as key enablers for Connected and Autonomous Vehicles (CAVs), offering virtual representations that support various applications ranging from offline, large-scale traffic analysis to real-time driver assistance. These use cases pose significantly diverse Quality of Service (QoS) requirements on DTs, including ultra-low latency for real-time synchronization with the physical counterparts. Deploying DTs at the network edge offers a promising solution, considering the increasingly advanced compute and network resources potentially available in a city-wide infrastructure. However, edge deployments introduce additional complexity: DT developers must deal with heterogeneous resources, optimize their usage for different QoS levels, and handle vehicle mobility. That process requires a high level of specialization and makes development time-consuming and error-prone. In this paper, we first introduce a DT communication model based on three key interfaces: to physical devices, to peer DTs, and to centralized applications. We then analyze the distinct QoS requirements of these interfaces and propose the adoption of a data distribution platform that maps them directly to edge network capabilities, hiding complexity and easing the DT development process. Early evaluations on a real testbed demonstrate the platform's potential to meet CAV DTs' QoS demands efficiently
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