Myristoylated GRASP55 dimerizes in the presence of model membranes.

The Golgi Reassembly and Stacking Proteins (GRASPs) are engaged in various functions within the cell, both in unconventional secretion mechanisms and structuring and organizing the Golgi apparatus. Understanding their specific role in each situation still requires more structural and functional data at the molecular level. GRASP55 is one of the GRASP members in mammals, anchored to the membrane via the myristoylation of a Gly residue at its N-terminus. Therefore, co-translational modifications, such as myristoylation, are fundamental when considering a strategy to obtain detailed information on the interactions between GRASP55 and membranes. Despite its functional relevance, the N-terminal myristoylation has been underappreciated in the studies reported to date, compromising the previously proposed models for GRASP-membrane interactions. Here, we investigated the synergy between the presence of the membrane and the formation of oligomeric structures of myristoylated GRASP55, using a series of biophysical techniques to perform the structural characterization of the lipidated GRASP55 and its interaction with biological lipid model membranes. Our data fulfill an unexplored gap: the adequate evaluation of the presence of lipidations and lipid membranes on the structure-function dyad of GRASPs.Communicated by Ramaswamy H. Sarma.

Antimicrobial Activity of an Fmoc-Plantaricin 149 Derivative Peptide against Multidrug-Resistant Bacteria.

Antimicrobial resistance poses a major threat to public health. Given the paucity of novel antimicrobials to treat resistant infections, the emergence of multidrug-resistant bacteria renewed interest in antimicrobial peptides as potential therapeutics. This study designed a new analog of the antimicrobial peptide Plantaricin 149 (Pln149-PEP20) based on previous Fmoc-peptides. The minimal inhibitory concentrations of Pln149-PEP20 were determined for 60 bacteria of different species and resistance profiles, ranging from 1 mg/L to 128 mg/L for Gram-positive bacteria and 16 to 512 mg/L for Gram-negative. Furthermore, Pln149-PEP20 demonstrated excellent bactericidal activity within one hour. To determine the propensity to develop resistance to Pln149-PEP20, a directed-evolution in vitro experiment was performed. Whole-genome sequencing of selected mutants with increased MICs and wild-type isolates revealed that most mutations were concentrated in genes associated with membrane metabolism, indicating the most likely target of Pln149-PEP20. Synchrotron radiation circular dichroism showed how this molecule disturbs the membranes, suggesting a carpet mode of interaction. Membrane depolarization and transmission electron microscopy assays supported these two hypotheses, although a secondary intracellular mechanism of action is possible. The molecule studied in this research has the potential to be used as a novel antimicrobial therapy, although further modifications and optimization remain possible.

Using crystallography tools to improve vaccine formulations.

This article summarizes developments attained in oral vaccine formulations based on the encapsulation of antigen proteins inside porous silica matrices. These vaccine vehicles show great efficacy in protecting the proteins from the harsh acidic stomach medium, allowing the Peyer's patches in the small intestine to be reached and consequently enhancing immunity. Focusing on the pioneering research conducted at the Butantan Institute in Brazil, the optimization of the antigen encapsulation yield is reported, as well as their distribution inside the meso- and macroporous network of the porous silica. As the development of vaccines requires proper inclusion of antigens in the antibody cells, X-ray crystallography is one of the most commonly used techniques to unveil the structure of antibody-combining sites with protein antigens. Thus structural characterization and modelling of pure antigen structures, showing different dimensions, as well as their complexes, such as silica with encapsulated hepatitis B virus-like particles and diphtheria anatoxin, were performed using small-angle X-ray scattering, X-ray absorption spectroscopy, X-ray phase contrast tomography, and neutron and X-ray imaging. By combining crystallography with dynamic light scattering and transmission electron microscopy, a clearer picture of the proposed vaccine complexes is shown. Additionally, the stability of the immunogenic complex at different pH values and temperatures was checked and the efficacy of the proposed oral immunogenic complex was demonstrated. The latter was obtained by comparing the antibodies in mice with variable high and low antibody responses.

Using crystallography tools to improve vaccine formulations

This article summarizes developments attained in oral vaccine formulations based on the encapsulation of antigen proteins inside porous silica matrices. These vaccine vehicles show great efficacy in protecting the proteins from the harsh acidic stomach medium, allowing the Peyer's patches in the small intestine to be reached and consequently enhancing immunity. Focusing on the pioneering research conducted at the Butantan Institute in Brazil, the optimization of the antigen encapsulation yield is reported, as well as their distribution inside the meso- and macroporous network of the porous silica. As the development of vaccines requires proper inclusion of antigens in the antibody cells, X-ray crystallography is one of the most commonly used techniques to unveil the structure of antibody-combining sites with protein antigens. Thus structural characterization and modelling of pure antigen structures, showing different dimensions, as well as their complexes, such as silica with encapsulated hepatitis B virus-like particles and diphtheria anatoxin, were performed using small-angle X-ray scattering, X-ray absorption spectroscopy, X-ray phase contrast tomography, and neutron and X-ray imaging. By combining crystallography with dynamic light scattering and transmission electron microscopy, a clearer picture of the proposed vaccine complexes is shown. Additionally, the stability of the immunogenic complex at different pH values and temperatures was checked and the efficacy of the proposed oral immunogenic complex was demonstrated. The latter was obtained by comparing the antibodies in mice with variable high and low antibody responses.

Lectin from red algae Amansia multifida Lamouroux: Extraction, characterization and anti-inflammatory activity.

Seaweed lectins are very promising biotechnological tools that also gain prominence when applied to the pharmacology field. The purpose of the present work was to isolate and characterize lectin from the red algae Amansia multifida and subsequently test it in general inflammation models. The lectin was purified by ion exchange chromatography, characterized with two-dimensional electrophoresis, automated analysis of amino acid sequences and circular dichroism spectroscopy. The pharmacological tests performed were paw edema induced by carrageenan or rapid inflammatory mediators, peritonitis induced by carrageenan and myeloperoxidase leukocyte count assays, glutathione and cytokine concentration. Our results have identified a 30 KDa molecular weight protein that presents a major secondary structure arranged in ß-strand elements (~43%). A fragment of 20 amino acid residues was sequenced and presented low identity to the known classes of lectins from marine alga. This lectin was able to modulate inflammatory parameters such as paw edema, leukocyte migration, oxidative stress and proinflammatory cytokines. Thus, the lectin from the seaweed Amansia multifida has evident anti-inflammatory properties because it acts by reducing the formation of edema by modulating the effect of vascular mediators, migration of neutrophils, proinflammatory cytokines and oxidative stress control.

Lectin obtained from the red seaweed Bryothamnion triquetrum: Secondary structure and anti-inflammatory activity in mice.

Seaweeds are sources of biomolecules with biological activities and pharmacological potential - for example, lectins, a group of proteins that can bind reversibly to carbohydrates or compounds containing them. The aim of this study was to elucidate the structural properties of a lectin extracted from the red seaweed Bryothamnion triquetrum (BtL) and to investigate its anti-inflammatory activity in mice. The lectin was purified by precipitation with ammonium sulfate and ion-exchange chromatography. Its secondary structure and tryptophan (Trp) microenvironment were analyzed by circular dichroism spectroscopy and steady-state fluorescence spectroscopy, respectively. The anti-inflammatory effect was evaluated by means of paw edema induced by carrageenan or dextran, myeloperoxidase activity in paw tissue, and by measurement of leukocyte and neutrophil migration and cytokine quantification in a peritonitis model. The secondary structure of BtL is mostly composed of ß-strands and unordered conformation, and it is quite resistant to extremes of pH and temperature, preserving the exposure of Trp residues under these conditions. In an assessment of biological activities, groups of mice were subjected to pretreatment with BtL before the inflammatory stimulus. BtL had anti-inflammatory effects in the models tested, and hence may be considered a molecule with potential to be used in the pharmaceutical industry.

Frog Foam Nest Protein Diversity and Synthesis.

Some amphibian species have developed a breeding strategy in which they deposit their eggs in stable foam nests to protect their eggs and larvae. The frog foam nests are rich in proteins (ranaspumin), especially surfactant proteins, involved in the production of the foam nest. Despite the ecological importance of the foam nests for evolution and species conservation, the biochemical composition, the long-term stability and even the origin of the components are still not completely understood. Recently we showed that Lv-RSN-1, a 23.5-kDa surfactant protein isolated from the nest of the frog Leptodacylus vastus, presents a structural conformation distinct from any protein structures yet reported. So, in the current study we aimed to reveal the protein composition of the foam nest of L. vastus and further characterize the Lv-RSN-1. Proteomic analysis showed the foam nest contains more than 100 of proteins, and that Lv-RSN-1 comprises 45% of the total proteins, suggesting a key role in the nest construction and stability. We demonstrated by Western blotting that Lv-RSN-1 is mainly produced only by the female in the pars convoluta dilata, which highlights the importance of the female preservation for conservation of species that depend on the production of foam nests in the early stages of development. Overall, our results showed the foam nest of L. vastus is composed of a great diversity of proteins and that besides Lv-RSN-1, the main protein in the foam, other proteins must have a coadjuvant role in building and stability of the nest.

New insights into the structure and mode of action of Mo-CBP3, an antifungal chitin-binding protein of Moringa oleifera seeds.

Mo-CBP3 is a chitin-binding protein purified from Moringa oleifera Lam. seeds that displays inhibitory activity against phytopathogenic fungi. This study investigated the structural properties and the antifungal mode of action of this protein. To this end, circular dichroism spectroscopy, antifungal assays, measurements of the production of reactive oxygen species and microscopic analyses were utilized. Mo-CBP3 is composed of 30.3% α-helices, 16.3% ß-sheets, 22.3% turns and 30.4% unordered forms. The Mo-CBP3 structure is highly stable and retains its antifungal activity regardless of temperature and pH. Fusarium solani was used as a model organism for studying the mechanisms by which this protein acts as an antifungal agent. Mo-CBP3 significantly inhibited spore germination and mycelial growth at 0.05 mg.mL-1. Mo-CBP3 has both fungistatic and fungicidal effects, depending on the concentration used. Binding of Mo-CBP3 to the fungal cell surface is achieved, at least in part, via electrostatic interactions, as salt was able to reduce its inhibitory effect. Mo-CBP3 induced the production of ROS and caused disorganization of both the cytoplasm and the plasma membrane in F. solani cells. Based on its high stability and specific toxicity, with broad-spectrum efficacy against important phytopathogenic fungi at low inhibitory concentrations but not to human cells, Mo-CBP3 has great potential for the development of new antifungal drugs or transgenic crops with enhanced resistance to phytopathogens.

Interaction of antimicrobial peptide Plantaricin149a and four analogs with lipid bilayers and bacterial membranes

The amidated analog of Plantaricin149, an antimicrobial peptide from Lactobacillus plantarum NRIC 149, directly interacts with negatively charged liposomes and bacterial membranes, leading to their lysis. In this study, four Pln149-analogs were synthesized with different hydrophobic groups at their N-terminus with the goal of evaluating the effect of the modifications at this region in the peptide's antimicrobial properties. The interaction of these peptides with membrane models, surface activity, their hemolytic effect on red blood cells, and antibacterial activity against microorganisms were evaluated. The analogs presented similar action of Plantaricin149a; three of them with no hemolytic effect (< 5%) until 0.5 mM, in addition to the induction of a helical element when binding to negative liposomes. The N-terminus difference between the analogs and Plantaricin149a retained the antibacterial effect on S. aureus and P. aeruginosa for all peptides (MIC50 of 19 µM and 155 µM to Plantaricin149a, respectively) but resulted in a different mechanism of action against the microorganisms, that was bactericidal for Plantaricin149a and bacteriostatic for the analogs. This difference was confirmed by a reduction in leakage action for the analogs. The lytic activity of Plantaricin149a is suggested to be a result of the peptide-lipid interactions from the amphipathic helix and the hydrophobic residues at the N-terminus of the antimicrobial peptide.

New small proteinase inhibitors from Capsicum annuum seeds: Characterization, stability, spectroscopic analysis and a cDNA cloning.

Recent results from our laboratory have previously shown the purification of a small serine proteinase inhibitor (PI), named CaTI1, from Capsicum annuum seeds. This work demonstrated the characterization of CaTI now named CaTI1, and the identification of two other small serine PIs, named CaTI2 and CaTI3, also present in these seeds. CaTI1 presented molecular mass of 6 kDa and pI value of ∼9.0. CaTI1 inhibited both trypsin and chymotrypsin with inhibition constants (Ki and Ki') of 14 and 2.8 nM for trypsin and 4.3 and 0.58 nM for chymotrypsin, respectively. Circular dichroism analysis suggested the predominance of both disordered and ß-strands regions in the secondary structure. CaTI1 presented striking physico-chemical stability. In an attempt to get the entire sequence of CaTI1 we found another PI called CaTI2. The discussion of this finding is in the main text. A degenerate primer was designed based on the sequence of trypsin inhibitor CaTI1 in an attempt to achieve the cloning of this PI. Surprisingly, the alignment of the predicted peptide derived from the cDNA with the protein database showed similarity with other C. annuun PIs, and thus it was called CaTI3.

Lipid interaction triggering Septin2 to assembly into ß-sheet structures investigated by Langmuir monolayers and PM-IRRAS.

The molecular mechanisms responsible for protein structural changes in the central nervous system leading to Alzheimer's disease are unknown, but there is evidence that a family of proteins known as septins may be involved. Septins are a conserved group of GTP-binding proteins which participate in various cellular processes, including polarity determination and membrane dynamics. SEPT1, SEPT4, and SEPT2 have been found in deposits known as neurofibrillary tangles and glial fibrils in Alzheimer's disease. In this study, we provide molecular-level information for the interaction of SEPT2 with Langmuir monolayers at the air/water interface, which are used as simplified membrane models. The high surface activity of SEPT2 causes it to adsorb onto distinct types of lipid Langmuir monolayers, namely dipalmitoylphosphatidylcholine and PtdIns(4,5)P2. However, the interaction with PtdIns(4,5)P2 is much stronger, not only leading to a higher adsorption, but also to SEPT2 remaining inserted within the membrane at high surface pressures. Most importantly, in situ polarization-modulated infrared reflection absorption spectroscopy results indicated that the native secondary structure of SEPT2 is preserved upon interacting with PtdIns(4,5)P2, but not when dipalmitoylphosphatidylcholine is at the air/water interface. Taken together, the results presented here suggest that the interaction between SEPT2 and the cell membrane may play an important role in the assembly of SEPT2 into amyloid-like fibers.

Interaction of antimicrobial peptide Plantaricin149a and four analogs with lipid bilayers and bacterial membranes.

The amidated analog of Plantaricin149, an antimicrobial peptide from Lactobacillus plantarum NRIC 149, directly interacts with negatively charged liposomes and bacterial membranes, leading to their lysis. In this study, four Pln149-analogs were synthesized with different hydrophobic groups at their N-terminus with the goal of evaluating the effect of the modifications at this region in the peptide's antimicrobial properties. The interaction of these peptides with membrane models, surface activity, their hemolytic effect on red blood cells, and antibacterial activity against microorganisms were evaluated. The analogs presented similar action of Plantaricin149a; three of them with no hemolytic effect (< 5%) until 0.5 mM, in addition to the induction of a helical element when binding to negative liposomes. The N-terminus difference between the analogs and Plantaricin149a retained the antibacterial effect on S. aureus and P. aeruginosa for all peptides (MIC50 of 19 µM and 155 µM to Plantaricin149a, respectively) but resulted in a different mechanism of action against the microorganisms, that was bactericidal for Plantaricin149a and bacteriostatic for the analogs. This difference was confirmed by a reduction in leakage action for the analogs. The lytic activity of Plantaricin149a is suggested to be a result of the peptide-lipid interactions from the amphipathic helix and the hydrophobic residues at the N-terminus of the antimicrobial peptide.

Osmotin from Calotropis procera latex: new insights into structure and antifungal properties.

This study aimed at investigating the structural properties and mechanisms of the antifungal action of CpOsm, a purified osmotin from Calotropis procera latex. Fluorescence and CD assays revealed that the CpOsm structure is highly stable, regardless of pH levels. Accordingly, CpOsm inhibited the spore germination of Fusarium solani in all pH ranges tested. The content of the secondary structure of CpOsm was estimated as follows: α-helix (20%), ß-sheet (33%), turned (19%) and unordered (28%), RMSD 1%. CpOsm was stable at up to 75°C, and thermal denaturation (T(m)) was calculated to be 77.8°C. This osmotin interacted with the negatively charged large unilamellar vesicles (LUVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-1-glycerol (POPG), inducing vesicle permeabilization by the leakage of calcein. CpOsm induced the membrane permeabilization of spores and hyphae from Fusarium solani, allowing for propidium iodide uptake. These results show that CpOsm is a stable protein, and its antifungal activity involves membrane permeabilization, as property reported earlier for other osmotins and thaumatin-like proteins.

Efeito da alteração ambiental sobre componentes psicológicos e parâmetros fisiológicos durante corrida em atletas / Effect of environment alteration in psychological components and physiological parameters during the treadmill running in athletes

Avaliou-se o efeito da alteração ambiental no afeto, percepção subjetiva do esforço e em parâmetros fisiológicos durante a corrida em atletas. Dezoito atletas de andebol atenderam a quatro sessões experimentais de corrida na esteira (linha de base, fragmentada, superestimada e indefinida) de 20 minutos. Foram avaliados: afeto, percepção subjetiva do esforço, frequência cardíaca e cortisol. Manipulou-se a informação sobre a duração da corrida. Verificou-se um aumento estatisticamente significativo para o afeto no decorrer da corrida das sessões "fragmentada" e "superestimada", assim como no nível de cortisol salivar aos 11 minutos da corrida. O controle do comportamento afetivo dos atletas parece amenizar desgastes fisiológicos frente a adversários desconhecidos e condições indefinidas de jogo.(AU)

It was evaluated the effect of environmental alteration in affect, perceived exertion and in physiological parameters during treadmill running in athletes. Eighteen handball players participated in four running experimental sessions (baseline, fragmented overrated and unknown) for 20 minutes. It was analyzed: affect, rating of perceived exertion, heart rate and cortisol. Information about the running duration was manipulated. It was observed a statistically significant increase in affect during the treadmill running for the "fragmented" and "overrated " sessions, as well as in salivary cortisol level at the 11th minute of running. The control of athletes' affective behavior seems to relieve physiological damage when facing unknown opponents and uncertain game conditions.(AU)

Efeito da alteração ambiental sobre componentes psicológicos e parâmetros fisiológicos durante corrida em atletas / Effect of environment alteration in psychological components and physiological parameters during the treadmill running in athletes

Avaliou-se o efeito da alteração ambiental no afeto, percepção subjetiva do esforço e em parâmetros fisiológicos durante a corrida em atletas. Dezoito atletas de andebol atenderam a quatro sessões experimentais de corrida na esteira (linha de base, fragmentada, superestimada e indefinida) de 20 minutos. Foram avaliados: afeto, percepção subjetiva do esforço, frequência cardíaca e cortisol. Manipulou-se a informação sobre a duração da corrida. Verificou-se um aumento estatisticamente significativo para o afeto no decorrer da corrida das sessões "fragmentada" e "superestimada", assim como no nível de cortisol salivar aos 11 minutos da corrida. O controle do comportamento afetivo dos atletas parece amenizar desgastes fisiológicos frente a adversários desconhecidos e condições indefinidas de jogo.

It was evaluated the effect of environmental alteration in affect, perceived exertion and in physiological parameters during treadmill running in athletes. Eighteen handball players participated in four running experimental sessions (baseline, fragmented overrated and unknown) for 20 minutes. It was analyzed: affect, rating of perceived exertion, heart rate and cortisol. Information about the running duration was manipulated. It was observed a statistically significant increase in affect during the treadmill running for the "fragmented" and "overrated " sessions, as well as in salivary cortisol level at the 11th minute of running. The control of athletes' affective behavior seems to relieve physiological damage when facing unknown opponents and uncertain game conditions.

Disruption of Saccharomyces cerevisiae by Plantaricin 149 and investigation of its mechanism of action with biomembrane model systems.

The action of a synthetic antimicrobial peptide analog of Plantaricin 149 (Pln149a) against Saccharomyces cerevisiae and its interaction with biomembrane model systems were investigated. Pln149a was shown to inhibit S. cerevisiae growth by more than 80% in YPD medium, causing morphological changes in the yeast wall and remaining active and resistant to the yeast proteases even after 24 h of incubation. Different membrane model systems and carbohydrates were employed to better describe the Pln149a interaction with cellular components using circular dichroism and fluorescence spectroscopies, adsorption kinetics and surface elasticity in Langmuir monolayers. These assays showed that Pln149a does not interact with either mono/polysaccharides or zwitterionic LUVs, but is strongly adsorbed to and incorporated into negatively charged surfaces, causing a conformational change in its secondary structure from random-coil to helix upon adsorption. From the concurrent analysis of Pln149a adsorption kinetics and dilatational surface elasticity data, we determined that 2.5 muM is the critical concentration at which Pln149a will disrupt a negative DPPG monolayer. Furthermore, Pln149a exhibited a carpet-like mechanism of action, in which the peptide initially binds to the membrane, covering its surface and acquiring a helical structure that remains associated to the negatively charged phospholipids. After this electrostatic interaction, another peptide region causes a strain in the membrane, promoting its disruption.