Dissecting the mechanism of action of actinoporins. Role of the N-terminal amphipathic α-helix in membrane binding and pore activity of sticholysins I and II

<div><p>Actinoporins sticholysin I and sticholysin II (St I, St II) are proposed to lyse model and biomembranes via toroidal pore formation by their N-terminal domain. Based on the hypothesis that peptide fragments can reproduce the structure and function of this domain, the behavior of peptides containing St I residues 12–31 (StI_12-31), St II residues 11–30 (StII_11-30), and its TOAC-labeled analogue (N-TOAC-StII_11-30) was examined. Molecular modeling showed a good match with experimental structures, indicating amphipathic α-helices in the same regions as in the toxins. CD spectra revealed that the peptides were essentially unstructured in aqueous solution, acquiring α-helical conformation upon interaction with micelles and large unilamellar vesicles (LUV) of variable lipid composition. Fluorescence quenching studies with NBD-containing lipids indicated that N-TOAC-StII_11-30’s nitroxide moiety is located in the membranes polar head group region. Pyrene-labeled phospholipid inter-leaflet redistribution suggested that the peptides form toroidal pores, according to the mechanism of action proposed for the toxins. Binding occurred only to negatively charged LUV, indicating the importance of electrostatic interactions; in contrast the peptides bound to both negatively charged and zwitterionic micelles, pointing to a lesser influence of these interactions. In addition, differences between bilayers and micelles in head group packing and in curvature led to differences in peptide-membrane interaction. We propose that the peptides topography in micelles resembles that of the toxins in the toroidal pore. The peptides mimicked the toxins permeabilizing activity, St II peptides being more effective than StI_12-31. To our knowledge, this is the first demonstration that differences in the toxins N-terminal amphipathic α-helix play a role in the difference between St I and St II activities.</p></div

Irrigation Scheduling in Crop Management System

Center pivor systems are widely used to suppress the irrigation needs of agricultural fields. In this article, we propose an autonomous to improve the low efficiency of this method of irrigation, developing a system based on the water requirement of the plantation, through field data (local temperature, local wind, soil moisture and precipitation forecast) and soil evapotranspiration calculation. The stored information will allow to calculatem the real evapotranspiration, not being necessary to restrict to lysometric measures. Accordingly, it is possible to schedule the irrigation for the period in which it has the lowest cost, considering the energy produced locally and the price of energy bought in the main market. Irrigation must be carried out within the time interval in which the plantation does not reach the wilding point, so it will be carried out at the time of the lowest cost.The present work was done and funded in the scope of the following project: Eco Rural IoT project funded by TETRAMAX-VALUECHAIN-TTX-1, and UID/EEA/00760/2019 funded by FEDER Funds through COMPETE program and by National Funds through FCT.info:eu-repo/semantics/publishedVersio

First synthesis of a fully active spin-labeled peptide hormone

For the first time in the electron spin resonance (ESR) and peptide synthesis fields, a fully active spin-labeled peptide hormone was reported. the ESR spectra of this alpha-melanocyte stimulating hormone (alpha-MSH) analogue (acetyl-Toac(0)-alpha-MSH) where Toac is the paramagnetic amino acid probe 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid, suggested a pH-independent conformation and a more restricted movement comparatively to the free Toac, Owing to its equivalent biological potency in a skin pigmentation assay as compared to the native alpha-MSH and its unique characteristic (paramagnetic, naturally fluorescent and fully active), this analogue is of great potential for investigation of relevant physiological roles reported for a-MSH, (C) 1999 Federation of European Biochemical Societies.Universidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilUniv São Paulo, Inst Fis, BR-01498 São Paulo, BrazilUniv São Paulo, Inst Biociencias, Dept Fisiol, BR-01498 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilWeb of Scienc

The State of the ReCLes. pt CLIL training project

Content and Language Integrated Learning (CLIL), an area that has only recently been more thoroughly explored for appropriate use at higher levels of education, has been one of the research areas identified by the Association of Language Centers in Higher Education in Portugal (ReCLes.pt). ReCLes.pt members – administration and research professors are striving to make a difference in the paucity of scientific publications in this area with the creation of their national program for training content teachers in Portuguese higher education. To best learn from each other in a collaborative network and apply well-informed teaching and learning methodology to English-taught classrooms, the underlying concepts range from classroom management and scaffolding to learner autonomy and from Web 2.0 tools to terminology-based learning. As an update of the current state of the art as interpreted in this project, the outreach and reception will be described in full with attention to some detailed examples of the more successful aspects as well as others where we have found room for improvement. Recommendations will be made for other networks and individual schools aiming to effectively prepare their students for the market by using an integrated approach to content and language learning. This paper reports on the current state of the ongoing ReCLes.pt CLIL Training Project, financed in part by the FCT (the Portuguese Foundation for Science and Technology), with project members from a number of universities and polytechnics across Portugal.info:eu-repo/semantics/publishedVersio

Comparative EPR and fluorescence conformational studies of fully active spin-labeled melanotropic peptides

Similar to melanocyte stimulating hormone (alpha -MSH), its potent and long-acting analogue, [Nle(4), D-Phe(7)]alpha -MSH, when labeled with the paramagnetic amino acid probe 2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid (Toac), maintains its full biological potency, thus validating any comparative structural investigations between the two labeled peptides, Correlation times, calculated from tire electron paramagnetic resonance signal of Toac bound to the peptides, and Toac-Trp distances, estimated from the Toac fluorescence quenching of the Trp residue present in the peptides, indicate a more rigid and folded structure for the potent analogue as compared to the hormone, in aqueous medium. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.Universidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilUniv São Paulo, Inst Fis, BR-66318 São Paulo, BrazilUniv São Paulo, Inst Biociencias, Dept Fisiol, BR-11176 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilWeb of Scienc

Photobiomodulation reduces the cytokine storm syndrome associated with Covid-19 in the zebrafish model

Although the exact mechanism of the pathogenesis of COVID-19 is not fully understood, oxidative stress and the release of pro-inflammatory cytokines have been highlighted as playing a vital role in the pathogenesis of the disease. In this sense, alternative treatments are needed to reduce the inflammation caused by COVID-19. Therefore, this study aimed to investigate the potential effect of red PBM as an attractive therapy to downregulate the cytokine storm caused by COVID-19 from a zebrafish model. RT-PCR analyses and protein-protein interaction prediction among SARS-CoV-2 and Danio rerio proteins showed that rSpike was responsible for generating systemic inflammatory processes with significantly increased pro-inflammatory (il1b, il6, tnfa, and nfkbiab), oxidative stress (romo1) and energy metabolism (slc2a1a, coa1) mRNA markers, with a pattern like those observed in COVID-19 cases in humans. On the other hand, PBM treatment decreased the mRNA levels of these pro-inflammatory and oxidative stress markers compared with rSpike in various tissues, promoting an anti-inflammatory response. Conversely, PBM promotes cellular and tissue repair of injured tissues and significantly increases the survival rate of rSpike-inoculated individuals. Additionally, metabolomics analysis showed that the most impacted metabolic pathways between PBM and the rSpike-treated groups were related to steroid metabolism, immune system, and lipids metabolism. Together, our findings suggest that the inflammatory process is an incisive feature of COVID-19, and red PBM can be used as a novel therapeutic agent for COVID-19 by regulating the inflammatory response. Nevertheless, the need for more clinical trials remains, and there is a significant gap to overcome before clinical trials.publishedVersio

EPR investigation of the influence of side chain protecting groups on peptide-resin solvation of the Asx and Glx model containing peptides

In spite of all progressive efforts aiming to optimize SPPS, serious problems mainly affecting the assembly of aggregating sequences have persisted. Following the study intended to unravel the complex solvation phenomenon of peptide-resin beads, the XING and XAAAA model aggregating segments were labeled with a paramagnetic probe and studied via EPR spectroscopy. Low and high substituted resins were also comparatively used, with the X residue being Asx or Glx containing the main protecting groups used in the SPPS. Notably, the cyclo-hexyl group used for Asp and Glu residues in Boc-chemistry induced greater chain immobilization than its tert-butyl partner-protecting group of the Fmoc strategy. Otherwise, the most impressive peptide chain immobilization occurred when the large trytil group was used for Asn and Gln protection in Fmoc-chemistry. These surprising results thus seem to stress the possibility of the relevant influence of the amino-acid side chain protecting groups in the overall peptide synthesis yield. (C) 2007 Elsevier B.V. All rights reserved.UNESP, Inst Chem Dept Biochem & Technol Chem, Araraquara, SP, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, SP, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, SP, BrazilWeb of Scienc

Interaction between the antimicrobial peptide Aurein 1.2 dimer and mannans

We have previously described the structure and the ability of a dimeric analog of the antimicrobial peptide Aurein 1.2 to aggregate Candida albicans. In this study, circular dichroism and fluorescence spectroscopy data showed that this aggregation is related to the interaction between the peptide and mannans, the main component of yeast cell wall. In this context, we propose a model in which dimers interact with the polysaccharide leading to cells aggregation.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES