The development of multifunctional particles using polymeric scaffolds is an emerging technology for many nanobiotechnological applications. Here we present a system for the production of multifunctional complexes, based on the high affinity non-covalent interaction of cohesin and dockerin modules complementary fused to decameric Brucella abortus lumazine synthase (BLS) subunits, and selected target proteins, respectively. The cohesin-BLS scaffold was solubly expressed in high yield in Escherichia coli, and revealed a high thermostability.
View Article and Find Full Text PDFFijiviruses replicate and package their genomes within viroplasms in a process involving RNA-RNA and RNA-protein interactions. Here, we demonstrate that the 24 C-terminal residues (C-arm) of the P9-1 major viroplasm protein of the mal de Río Cuarto virus (MRCV) are required for its multimerization and the formation of viroplasm-like structures. Using an integrative structural approach, the C-arm was found to be dispensable for P9-1 dimer assembly but essential for the formation of pentamers and hexamers of dimers (decamers and dodecamers), which favored RNA binding.
View Article and Find Full Text PDFPLoS One
September 2022
Background: Passive immunotherapy has been evaluated as a therapeutic alternative for patients with COVID-19 disease. Equine polyclonal immunotherapy for COVID-19 (EPIC) showed adequate safety and potential efficacy in a clinical trial setting and obtained emergency use authorization in Argentina. We studied its utility in a real world setting with a larger population.
View Article and Find Full Text PDFVoltage-gated sodium channels, Nas, are responsible for the rapid rise of action potentials in excitable tissues. Na channel mutations have been implicated in several human genetic diseases, such as hypokalemic periodic paralysis, myotonia, and long-QT and Brugada syndromes. Here, we generated high-affinity anti-Na nanobodies (Nbs), Nb17 and Nb82, that recognize the Na1.
View Article and Find Full Text PDFRes Vet Sci
July 2022
Brucella ovis is an economically important cause of epididymitis in rams worldwide. Polymeric BLSOmp31 was previously identified as a protective immunogen against this pathogen. In this study, BLSOmp31 was formulated with a modified version of ISCOMATRIX adjuvant called ISPA (BLSOmp31/ISPA) and was administered in BALB/C by the subcutaneous and ocular route.
View Article and Find Full Text PDFPhytochromes constitute a widespread photoreceptor family that typically interconverts between two photostates called Pr (red light–absorbing) and Pfr (far-red light–absorbing). The lack of full-length structures solved at the (near-)atomic level in both pure Pr and Pfr states leaves gaps in the structural mechanisms involved in the signal transmission pathways during the photoconversion. Here, we present the crystallographic structures of three versions from the plant pathogen virulence regulator BphP bacteriophytochrome, including two full-length proteins, in the Pr and Pfr states.
View Article and Find Full Text PDFThe ability to sense and respond to environmental cues is essential for adaptation and survival in living organisms. In bacteria, this process is accomplished by multidomain sensor histidine kinases that undergo autophosphorylation in response to specific stimuli, thereby triggering downstream signaling cascades. However, the molecular mechanism of allosteric activation is not fully understood in these important sensor proteins.
View Article and Find Full Text PDFRed/far-red light-sensing bacteriophytochrome photoreceptor (BphP) pathways play key roles in bacterial physiology and ecology. These bilin-binding proteins photoswitch between two states, Pr (red absorbing) and Pfr (far-red absorbing). The isomerization of the chromophore and the downstream structural changes result in the light signal transduction.
View Article and Find Full Text PDFRes Vet Sci
March 2021
Previously, we demonstrated that the chimera BLSOmp31 formulated in chitosan microspheres or Poloxamer407-Chitosan administered via the nasal and the ocular mucosa conferred partial protection in sheep against B. ovis. In this work, we tested a new delivery system for mucosal immunization with BLSOmp31 in the murine model to improve the efficacy of previously used formulations.
View Article and Find Full Text PDFActa Crystallogr D Struct Biol
November 2020
Carbohydrate-lectin interactions are involved in important cellular recognition processes, including viral and bacterial infections, inflammation and tumor metastasis. Hence, structural studies of lectin-synthetic glycan complexes are essential for understanding lectin-recognition processes and for the further design of promising chemotherapeutics that interfere with sugar-lectin interactions. Plant lectins are excellent models for the study of the molecular-recognition process.
View Article and Find Full Text PDFTailed bacteriophages are one of the most widespread biological entities on Earth. Their singular structures, such as spikes or fibers are of special interest given their potential use in a wide range of biotechnological applications. In particular, the long fibers present at the termini of the T4 phage tail have been studied in detail and are important for host recognition and adsorption.
View Article and Find Full Text PDFPhytochromes are photosensitive proteins with a covalently bound open-chain chromophore that can switch between two principal states: red light absorbing Pr and far-red light absorbing Pfr. Our group has previously shown that the bacteriophytochrome from Xanthomonas campestris pv. campestris (XccBphP) is a bathy-like phytochrome that uses biliverdin IXα as a co-factor and is involved in bacterial virulence.
View Article and Find Full Text PDFThe disease named COVID-19, caused by the SARS-CoV-2 coronavirus, is currently generating a global pandemic. Vaccine development is no doubt the best long-term immunological approach, but in the current epidemiologic and health emergency there is a need for rapid and effective solutions. Convalescent plasma is the only antibody-based therapy available for COVID-19 patients to date.
View Article and Find Full Text PDFThe multi-copper Laccase enzyme corresponds to one of the most investigated oxidoreductases for potential uses in xenobiotic bioremediation. In this work, we have investigated the photo-degradation process of Laccase from Trametesversicolor induced by UVB light and the influence on its activity over selected substrates. Laccase undergoes photo-degradation when irradiated with UVB light, and the process depends on the presence of oxygen in the medium.
View Article and Find Full Text PDFBackground: Natural killer and cytotoxic CD8 T cells are major players during antitumor immunity. They express NKG2D, an activating receptor that promotes tumor elimination through recognition of the MHC class I chain-related proteins A and B (MICA and MICB). Both molecules are overexpressed on a great variety of tumors from different tissues, making them attractive targets for immunotherapy.
View Article and Find Full Text PDFShiga toxin (Stx)-producing (STEC) is the main cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening clinical complication characterized by hemolytic anemia, thrombocytopenia, and acute renal failure that mainly affects children. A relevant feature of STEC strains is the production of Stx, and all of them express Stx1 and/or Stx2 regardless of the strain serotype. Therefore, Stx detection assays are considered the most suitable methods for the early detection of STEC infections.
View Article and Find Full Text PDFX-ray crystallography provides structural information of molecules at the atomic level, being a central technique at the forefront of science and technology. However, crystallography teaching is not usually implemented in biochemistry lab classes due to its complex execution by nonexpert users. Here, we report the basic step-by-step workflow performed by crystallographers in order to solve the three-dimensional structure of a protein.
View Article and Find Full Text PDFBrucella spp. are pathogenic intracellular Gram-negative bacteria adapted to life within cells of several mammals, including humans. These bacteria are the causative agent of brucellosis, one of the zoonotic infections with the highest incidence in the world and for which a human vaccine is still unavailable.
View Article and Find Full Text PDFVet Immunol Immunopathol
March 2019
Subcellular vaccines against ovine contagious epididymitis due Brucella ovis can solve some shortcomings associated with the use of Brucella melitensis Rev 1. We have demonstrated that the parenteral immunization with polymeric antigen BLSOmp31 emulsified in oil adjuvant conferred significant protection against B. ovis in rams.
View Article and Find Full Text PDFEngineering oligomeric protein self-assembly is an attractive approach to fabricate nanostructures with well-defined geometries, stoichiometry and functions. The homodecamer Lumazine Synthase (BLS) is a highly stable and immunogenic protein nanoparticle (PNP). Here, we engineered the BLS protein scaffold to display two functions in spatially opposite regions of its structure yielding a Janus-like nanoparticle.
View Article and Find Full Text PDFVaccination is as one of the most beneficial biopharmaceutical interventions against pathogens due to its ability to induce adaptive immunity through targeted activation of the immune system. Each vaccine needs a tailor-made set of tests in order to monitor its quality throughout the development and manufacturing. The analysis of the conformational state of protein nanoparticles is one of the key steps in vaccine quality control.
View Article and Find Full Text PDFBackground: Scientific and professional development opportunities for early career scientists in low- and middle- income countries (LMICs) are limited and not consistent. There is a disproportionately low number of biomedical and clinical researchers in LMIC's relative to their high burden of disease, a disparity that is aggravated by emigration of up to 70% of scientists from their countries of birth for education and employment elsewhere. To help address this need, a novel University-accredited, immersive fellowship program was established by a large public-academic-private network.
View Article and Find Full Text PDFThe pathogenic bacterium codes for a multi-domain dimeric cytoplasmic histidine kinase called LOV-HK, which is a key blue light-activated virulence factor in this microorganism. The structural basis of the light activation mechanism of this protein remains unclear. In this work, full-length LOV-HK was cloned, expressed and purified.
View Article and Find Full Text PDFMany signaling pathways that control cellular development, cell-cycle progression and nutritional versatility have been studied in Caulobacter crescentus. For example, it was suggested that the response regulator NtrX is conditionally essential for this bacterium and that it might be necessary for responding to a signal produced in phosphate-replete minimal medium. However, such signal has not been identified yet and the role of NtrX in C.
View Article and Find Full Text PDFHere, we report the draft genome sequence of sp. strain V23, a bacterium isolated from accretion ice of the subglacial Lake Vostok (3,592 meters below the surface). This genome makes possible the study of ancient and psychrophilic genes and proteins from a subglacial environment isolated from the surface for at least 15 million years.
View Article and Find Full Text PDF