The Distinctive Regulation of Cyanobacterial Glutamine Synthetase

Glutamine synthetase (GS) features prominently in bacterial nitrogen assimilation as it catalyzes the entry of bioavailable nitrogen in form of ammonium into cellular metabolism. The classic example, the comprehensively characterized GS of enterobacteria, is subject to exquisite regulation at multiple levels, among them gene expression regulation to control GS abundance, as well as feedback inhibition and covalent modifications to control enzyme activity. Intriguingly, the GS of the ecologically important clade of cyanobacteria features fundamentally different regulatory systems to those of most prokaryotes. These include the interaction with small proteins, the so-called inactivating factors (IFs) that inhibit GS linearly with their abundance. In addition to this protein interaction-based regulation of GS activity, cyanobacteria use alternative elements to control the synthesis of GS and IFs at the transcriptional level. Moreover, cyanobacteria evolved unique RNA-based regulatory mechanisms such as glutamine riboswitches to tightly tune IF abundance. In this review, we aim to outline the current knowledge on the distinctive features of the cyanobacterial GS encompassing the overall control of its activity, sensing the nitrogen status, transcriptional and post-transcriptional regulation, as well as strain-specific differences.Deutsche Forschungsgemeinschaft KL 3114/2-1Ministerio de Economía y Competitividad BIO2016-75634-PFEDER BIO2016-75634-

Intrinsically disordered inhibitor of glutamine synthetase is a functional protein with random-coil-like pKa values

The sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT) in cyanobacteria allows the incorporation of ammonium into carbon skeletons. In the cyanobacterium Synechocystis sp. PCC 6803, the activity of GS is modulated by the interaction with proteins, which include a 65-residue-long intrinsically disordered protein (IDP), the inactivating factor IF7. This interaction is regulated by the presence of charged residues in both IF7 and GS. To understand how charged amino acids can affect the binding of an IDP with its target and to provide clues on electrostatic interactions in disordered states of proteins, we measured the pKa values of all IF7 acidic groups (Glu32, Glu36, Glu38, Asp40, Asp58, and Ser65, the backbone C-terminus) at 100 mM NaCl concentration, by using NMR spectroscopy. We also obtained solution structures of IF7 through molecular dynamics simulation, validated them on the basis of previous experiments, and used them to obtain theoretical estimates of the pKa values. Titration values for the two Asp and three Glu residues of IF7 were similar to those reported for random-coil models, suggesting the lack of electrostatic interactions around these residues. Furthermore, our results suggest the presence of helical structure at the N-terminus of the protein and of conformational changes at acidic pH values. The overall experimental and in silico findings suggest that local interactions and conformational equilibria do not play a role in determining the electrostatic features of the acidic residues of IF7.Ministerio de Economía y Competitividad CTQ 2015-64445-R, BFU2013- 41712-P, BIO2016-75634PJunta de Andalucía BIO-284Generalitat Valenciana Prometeo 018/201

NADP(+)-isocitrate dehydrogenase from the cyanobacterium Anabaena sp. strain PCC 7120: purification and characterization of the enzyme and cloning, sequencing, and disruption of the icd gene

NADP(+)-isocitrate dehydrogenase (NADP(+)-IDH) from the dinitrogen-fixing filamentous cyanobacterium Anabaena sp. strain PCC 7120 was purified to homogeneity. The native enzyme is composed of two identical subunits (M(r), 57,000) and cross-reacts with antibodies obtained against the previously purified NADP(+)-IDH from the unicellular cyanobacterium Synechocystis sp. strain PCC 6803. Anabaena NADP(+)-IDH resembles in its physicochemical and kinetic parameters the typical dimeric IDHs from prokaryotes. The gene encoding Anabaena NADP(+)-IDH was cloned by complementation of an Escherichia coli icd mutant with an Anabaena genomic library. The complementing DNA was located on a 6-kb fragment. It encodes an NADP(+)-IDH that has the same mobility as that of Anabaena NADP(+)-IDH on nondenaturing polyacrylamide gels. The icd gene was subcloned and sequenced. Translation of the nucleotide sequence gave a polypeptide of 473 amino acids that showed high sequence similarity to the E. coli enzyme (59% identity) and with IDH1 and IDH2, the two subunits of the heteromultimeric NAD(+)-IDH from Saccharomyces cerevisiae (30 to 35% identity); however, a low level of similarity to NADP(+)-IDHs of eukaryotic origin was found (23% identity). Furthermore, Anabaena NADP(+)-IDH contains a 44-residue amino acid sequence in its central region that is absent in the other IDHs so far sequenced. Attempts to generate icd mutants by insertional mutagenesis were unsuccessful, suggesting an essential role of IDH in Anabaena sp. strain PCC 7120.España, Dirección General de Investigación Científica y Técnica (grant PB91-0127

Incorporating Digital Health Literacy into Adult ESL Education on the US-Mexico Border

The increasing digitization of information and communication has undoubtedly impacted the ways in which people in the United States access and interpret health information. Although the traditional emphasis of health literacy research has been the comprehension of health-related texts such as patient information forms, prescriptions, and medicine labels, the increased use of electronic means to locate health information requires more critical engagement with texts beyond basic comprehension. In accessing electronic health information, patients need to be able to navigate the vast amount of online health information and to interpret and synthesize health information across multiple sources (i.e. websites) while also evaluating the credibility of these sources. Recent health literacy research has examined the increased role of the media literacy in influencing health behaviors (Bergsma & Carney, 2008) and the role of increased access to computers (Salovey et al., 2009), but little (if any) research to date has provided recommendations for best practices related to meeting the health literacy demands required by digitization. This article attempts to fill this gap by exploring the use of the internet as a key source of health information and by looking at best practices in teaching digital health literacy. It describes the development of a digital literacy component within a community-based health literacy/ESL curriculum funded by the National Institutes of Health and implemented on the US-Mexico border

Planificación y optimización de redes ópticas en el Internet del futuro

[SPA] Las estrictas exigencias requeridas por la futura red 5G, junto a las elevadas previsiones de crecimiento de tráfico IP, principalmente cimentadas en la proliferación de numerosos servicios basados en la nube, crean un panorama futuro lleno de incógnitas desde la perspectiva de las grandes redes ópticas de telecomunicaciones. Las tareas de planificación y optimización serán esenciales para asegurar que los requisitos pueden cumplirse de una manera económicamente viable. Esta tesis trata de analizar, en primer lugar, la validez de las predicciones de crecimiento tráfico, a la luz de las actuales aplicaciones y en un escenario donde los requisitos de latencia implican la evolución de los CDNs con el despliegue de micro-datacenters. Se analizará en particular el efecto de esta evolución en el tráfico soportado por las redes ópticas troncales. Segundo, la tesis estudia opciones que permitan abordar los requisitos esperados de la red, desde tres enfoques: a) optimización en el diseño y gestión de CDNs, b) control programable de la red basado, en redes definidas por software (SDN) y con virtualización en las funciones de red (NFV) y por último, c) posible introducción de tecnología SDM (Space Division Multiplexing) para expandir la capacidad de las redes de transporte como soporte efectivo del incremento de tráfico IP. Los resultados de este trabajo concluyen, en primera instancia, que la evolución del tráfico troncal en el Internet del futuro dependerá de la naturaleza de los servicios que las aplicaciones ofrezca, siendo el balance entre el tráfico de usuario y de sincronización especialmente determinante. Por otro lado, los resultados sugieren que un acercamiento del contenido a los usuarios puede tener el efecto neto de disminuir la cantidad de tráfico soportada por las redes core, en relación con las previsiones actuales. Los casos de uso analizados en el entorno SDN-NFV determinan la necesidad de optimización para proporcionar flexibilidad y programabilidad en la migración hacia sistemas virtualizados en las redes, siendo este conjunto de funcionalidades esenciales para satisfacer los requerimientos de los futuros servicios en el paradigma 5G. Además, las pruebas de concepto presentadas avalan la optimización conjunta de recursos de red e IT para la asistencia de service chains en redes basadas en SDN-NFV. Finalmente, para las redes ópticas basadas en SDM, la propuesta presentada de restricción de canal espacial (SCC) emerge como una opción válida a implementar en ROADMs para contextos flex-grid. La validez de tal propuesta reside en la reducción de coste de implementación dada por su menor complejidad y mayor disponibilidad de equipamiento, a costa de mínimas pérdidas en rendimiento, respecto de opciones totalmente permisivas.[ENG] The strict requirements required for the future 5G network, jointly with the high growth forecasts of IP traffic, mainly based on the proliferation of cloud services, create a future panorama full of uncertainties from the perspective of large optical telecommunications networks. Planning and optimization tasks are essential to ensure that the requirements are satisfied in an economically viable manner. This thesis tries to analyze, in the first place, the validity of traffic growth predictions, in the light of current applications in a scenario where the latency requirements imply the evolution of CDNs with the deployment of micro-datacenters. In particular, the effect of this traffic evolution, supported by the optical backbone networks, will be analyzed. Second, the thesis studies some options that allow addressing the expected requirements of the network, from the perspective of three major approaches: a) optimization in the design and management of CDNs, b) programmable control of the network based on software-defined networking and with virtualization in network functions and finally, c) possible introduction of the Space Division Multiplexing (SDM) technology to expand the capacity of transport networks as effective support for the increase of IP traffic. The outcomes of this work conclude, in the first instance, that the evolution of the backbone traffic in the future Internet will depend on the nature of the services that the applications offer, being the balance between user traffic and synchronization one especially determining. On the other hand, the results suggest that place the content close to the users can have direct effect of decreasing the amount of traffic supported by the core networks, in relation to the current forecasts. The use cases analyzed in the SDN-NFV environment determine the need for optimization providing flexibility and programmability in the migration to virtualized systems in the networks. This set of functionalities are essential to satisfy the requirements of the future services in the 5G paradigm. In addition, the proof of concept presented in this thesis supports the joint optimization of network and IT resources for the assistance of service chains in networks based on SDN-NFV. Finally, for SDM-based optical networks, the proposal presented for space channel restriction (SCC) emerges as a valid option to be implemented in ROADMs for flex-grid environments. The validity of this proposal lies in the significant reduction in terms of implementation cost due to its lower complexity and the current availability of the equipment, at the expense of minimal performance degradations, compared to totally permissive options.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma de Doctorado en Tecnologías de la Información y las Comunicaciones por la Universidad Politécnica de Cartagen

Control of Delayed Recycling Systems with an Unstable Pole at Forward Path

International audienceUnstable time delay system and recycling system pose a challenge problem in their own. When unstable time delay system have recycle the control problem becomes even more difficult. A control methodology for these systems is proposed in this paper. The strategy is based on the observation that if some internal system were available, then it would be possible to decouple the backward dynamics and then a feedback controller could be designed for the forward dynamics. The key for this strategy to be carried out is the asymptotic observerpredictor proposed to estimate the required internal signals. Necessary and sufficient conditions to assure convergence of this observer are given. Then, the strategy is complemented by using a PID controller with two degree of freedom in order to track step input references. Robustness to delay uncertainty is also discussed