Roles of transcriptional and translational control mechanisms in regulation of ribosomal protein synthesis in Escherichia coli

ABSTRACTBacterial ribosome biogenesis is tightly regulated to match nutritional conditions and to prevent formation of defective ribosomal particles. InEscherichia coli, most ribosomal protein (r-protein) synthesis is coordinated with rRNA synthesis by a translational feedback mechanism: when r-proteins exceed rRNAs, specific r-proteins bind to their own mRNAs and inhibit expression of the operon. It was recently discovered that the second messenger nucleotide guanosine tetra and pentaphosphate (ppGpp), which directly regulates rRNA promoters, is also capable of regulating many r-protein promoters. To examine the relative contributions of the translational and transcriptional control mechanisms to the regulation of r-protein synthesis, we devised a reporter system that enabled us to genetically separate thecis-acting sequences responsible for the two mechanisms and to quantify their relative contributions to regulation under the same conditions. We show that the synthesis of r-proteins from the S20 and S10 operons is regulated by ppGpp following shifts in nutritional conditions, but most of the effect of ppGpp required the 5′ region of the r-protein mRNA containing the target site for translational feedback regulation and not the promoter. These results suggest that most regulation of the S20 and S10 operons by ppGpp following nutritional shifts is indirect and occurs in response to changes in rRNA synthesis. In contrast, we found that the promoters for the S20 operon were regulated during outgrowth, likely in response to increasing nucleoside triphosphate (NTP) levels. Thus, r-protein synthesis is dynamic, with different mechanisms acting at different times.IMPORTANCEBacterial cells have evolved complex and seemingly redundant strategies to regulate many high-energy-consuming processes. InE. coli, synthesis of ribosomal components is tightly regulated with respect to nutritional conditions by mechanisms that act at both the transcription and translation steps. In this work, we conclude that NTP and ppGpp concentrations can regulate synthesis of ribosomal proteins, but most of the effect of ppGpp is indirect as a consequence of translational feedback in response to changes in rRNA levels. Our results illustrate how effects of seemingly redundant regulatory mechanisms can be separated in time and that even when multiple mechanisms act concurrently their contributions are not necessarily equivalent.</jats:p

THERMOGRAVIMETRIC ANALYSIS OF THERMAL AND KINETIC BEHAVIOR OF ACACIA MANGIUM WOOD

Thermogravimetric analysis was used to study the thermal behavior of Acacia mangium wood under inert atmosphere at heating rates ranging from 5 to 15C min -1, from room temperature to 800C. Weight losses of A. mangium wood in inert atmosphere were found to occur in three stages. These three states are generally associated with the decomposition of the three main components of the lignocellulosic materials. Most decomposition occurred in the range of 300-400C (80% weight approximately). The kinetic parameters of the process were evaluated using the independent parallel reaction model, attributed to the three main components of lignocellulosic materials: hemicelluloses, cellulose, and lignin. The values of activation energy, preexponential factor, and contribution factor were similar to those reported in other studies for this type of biomass. The model proposed predicted an acceptable correlation between the experimental and the calculated curve to the decomposition of A. mangium, with an error of less than 3% of deviation in the temperature range studied

Expansion of Intrinsically Disordered Proteins Increases the Range of Stability of Liquid-Liquid Phase Separation.

Proteins containing intrinsically disordered regions (IDRs) are ubiquitous within biomolecular condensates, which are liquid-like compartments within cells formed through liquid-liquid phase separation (LLPS). The sequence of amino acids of a protein encodes its phase behaviour, not only by establishing the patterning and chemical nature (e.g., hydrophobic, polar, charged) of the various binding sites that facilitate multivalent interactions, but also by dictating the protein conformational dynamics. Besides behaving as random coils, IDRs can exhibit a wide-range of structural behaviours, including conformational switching, where they transition between alternate conformational ensembles. Using Molecular Dynamics simulations of a minimal coarse-grained model for IDRs, we show that the role of protein conformation has a non-trivial effect in the liquid-liquid phase behaviour of IDRs. When an IDR transitions to a conformational ensemble enriched in disordered extended states, LLPS is enhanced. In contrast, IDRs that switch to ensembles that preferentially sample more compact and structured states show inhibited LLPS. This occurs because extended and disordered protein conformations facilitate LLPS-stabilising multivalent protein-protein interactions by reducing steric hindrance; thereby, such conformations maximize the molecular connectivity of the condensed liquid network. Extended protein configurations promote phase separation regardless of whether LLPS is driven by homotypic and/or heterotypic protein-protein interactions. This study sheds light on the link between the dynamic conformational plasticity of IDRs and their liquid-liquid phase behaviour

An in silico analysis identifies drugs potentially modulating the cytokine storm triggered by SARS-CoV-2 infection

The ongoing COVID-19 pandemic is one of the biggest health challenges of recent decades. Among the causes of mortality triggered by SARS-CoV-2 infection, the development of an inflammatory “cytokine storm” (CS) plays a determinant role. Here, we used transcriptomic data from the bronchoalveolar lavage fluid (BALF) of COVID-19 patients undergoing a CS to obtain gene-signatures associated to this pathology. Using these signatures, we interrogated the Connectivity Map (CMap) dataset that contains the effects of over 5000 small molecules on the transcriptome of human cell lines, and looked for molecules which effects on transcription mimic or oppose those of the CS. As expected, molecules that potentiate immune responses such as PKC activators are predicted to worsen the CS. In addition, we identified the negative regulation of female hormones among pathways potentially aggravating the CS, which helps to understand the gender-related differences in COVID-19 mortality. Regarding drugs potentially counteracting the CS, we identified glucocorticoids as a top hit, which validates our approach as this is the primary treatment for this pathology. Interestingly, our analysis also reveals a potential effect of MEK inhibitors in reverting the COVID-19 CS, which is supported by in vitro data that confirms the anti-inflammatory properties of these compounds.Open access funding provided by Karolinska Institute.S

Solar Panels for Scientific Missions Using CubeSat Platforms for LEO, MEO and GTO

DHV Technology is a company specialized on the designing, manufacturing and testing of solar panels for CubeSats and Small Satellites. In this presentation is discussed about solar panels of CubeSat missions developed for Scientific missions with Space Agencies involved as CNES, ESA and NASA Goddard. DHV Technology have developed the solar panels for Angels mission developed by HEMERIA and CNES based on a 12U platform, the solar panels for GTOSat mission developed by NASA Goddard based on a 3U CubeSat and the solar panels of TRISAT-R mission developed by Maribor University and funded by ESA using a 3U CubeSat. Angels mission is a LEO mission for Earth Observation with a payload developed by Syrlinksand Thales Alenia Space to analyze the state of the oceans, GTOSat mission is a GTO mission to acquire new data about high energy particles and TRISAT-R mission is a MEO mission for in-orbit demonstration. The requirements on solar panels for LEO, MEO and GTO missions will be analyzed in this presentation and other subjects as qualification process and the quality assurance will be discussed. There are some key points that are analyzed in this presentation as the features of the solar panels for high radiation environment, the resistance torque analysis and the harness design, the electrical losses analysis and the ATOX degradation analysis

Valency and Binding Affinity Variations Can Regulate the Multilayered Organization of Protein Condensates with Many Components.

Biomolecular condensates, which assemble via the process of liquid-liquid phase separation (LLPS), are multicomponent compartments found ubiquitously inside cells. Experiments and simulations have shown that biomolecular condensates with many components can exhibit multilayered organizations. Using a minimal coarse-grained model for interacting multivalent proteins, we investigate the thermodynamic parameters governing the formation of multilayered condensates through changes in protein valency and binding affinity. We focus on multicomponent condensates formed by scaffold proteins (high-valency proteins that can phase separate on their own via homotypic interactions) and clients (proteins recruited to condensates via heterotypic scaffold-client interactions). We demonstrate that higher valency species are sequestered to the center of the multicomponent condensates, while lower valency proteins cluster towards the condensate interface. Such multilayered condensate architecture maximizes the density of LLPS-stabilizing molecular interactions, while simultaneously reducing the surface tension of the condensates. In addition, multilayered condensates exhibit rapid exchanges of low valency proteins in and out, while keeping higher valency proteins-the key biomolecules involved in condensate nucleation-mostly within. We also demonstrate how modulating the binding affinities among the different proteins in a multicomponent condensate can significantly transform its multilayered structure, and even trigger fission of a condensate into multiple droplets with different compositions.Engineering and Physical Sciences Research Council (EPSRC) scholarship to Ignacio Sanchez-Burgo

Integrating affection, emotion, and aesthetics into a General Theory of Learning

Every learning process is an affective experience. Affect is central in experiencing learning as uncertainty. This article proposes an internal integration of affect into the learning process. The main concepts of learning are articulated with a take on the reflection framework and a dynamic and social understanding of affection, emotions, and aesthetic experiences, helping to integrate concepts like edge-emotions and liminal experiences into the learning process. These concepts support the idea that complex emotions play a central part in learning dynamics, while arguing for reflection as a self-regulatory movement of the learning process. It is argued that there would be no such thing as a merely cognitive learning process. Every time that people learn, they experience edge-emotions and liminal experiences. Furthermore, if the learning process occurs in educational settings, it is possible to think about learning experiences as being mediated by liminal affective techniques and so, open to transformation

Marketing digital y la empleabilidad en jóvenes graduados del pregrado en universidades de la ciudad de Trujillo, 2023

La investigación tuvo como objetivo general determinar la relación entre el marketing digital y la empleabilidad en los jóvenes graduados del pregrado de universidades de la ciudad de Trujillo, 2023. La investigación fue de tipo aplicada, de diseño no experimental y transversal. La población estuvo conformada por los graduados de las universidades de la ciudad de Trujillo, la muestra estuvo conformada por 365 graduados. Se utilizó un cuestionario de 25 preguntas. El 67,40% de los jóvenes graduados muestran un nivel medio de marketing digital; debido principalmente a que no usan estrategias de marketing digital para elaborar su perfil de competencias. El 58.90% de los jóvenes graduados afirman que el nivel de empleabilidad es medio; debido a que consideran que hay ocasiones en las que no se sienten muy capaces para evaluar y clasificar las distintas opciones que les permita tomar una decisión. Los resultados evidencian que existe un valor de significancia del 0.000; así también un valor de correlación de Spearman de 0.599; lo cual indica que existe una relación positiva entre marketing digital y la empleabilidad en los jóvenes graduados del pregrado de universidades de la ciudad de Trujillo, 2023