Person: Martínez Del Pozo, Álvaro
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First Name
Álvaro
Last Name
Martínez Del Pozo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Bioquímica y Biología Molecular
Area
Bioquímica y Biología Molecular
Identifiers
67 results
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Now showing 1 - 10 of 67
Item Der p 1‑based immunotoxin as potential tool for the treatment of dust mite respiratory allergy(Scientific Reports, 2020) Lázaro‑Gorines, Rodrigo; López Rodríguez, Juan Carlos; Benedé Pérez, Sara; González, Miguel; Mayorga, Cristobalina; Vogel, Lothar; Martínez Del Pozo, Álvaro; Lacadena García-Gallo, Francisco Javier; Villalba Díaz, María TeresaImmunotoxins appear as promising therapeutic molecules, alternative to allergen-specifcimmunotherapy. In this work, we achieved the development of a protein chimera able to promote specifc cell death on efector cells involved in the allergic reaction. Der p 1 allergen was chosen as cell-targeting domain and the powerful ribotoxin α-sarcin as the toxic moiety. The resultant construction, named proDerp1αS, was produced and purifed from the yeast Pichia pastoris. Der p 1-protease activity and α-sarcin ribonucleolytic action were efectively conserved in proDerp1αS. Immunotoxin impact was assayed by using efector cells sensitized with house dust mite-allergic sera. Cell degranulation and death, triggered by proDerp1αS, was exclusively observed on Der p 1 sera sensitized-humRBL-2H3 cells, but not when treated with non-allergic sera. Most notably, equivalent IgE-binding and degranulation were observed with both proDerp1αS construct and native Der p 1 when using purifed basophils from sensitized patients. However, proDerp1αS did not cause any cytotoxic efect on these cells, apparently due to its lack of internalization after their surface IgEbinding, showing the complex in vivo panorama governing allergic reactions. In conclusion, herein we present proDerp1αS as a proof of concept for a potential and alternative new designs of therapeutic tools for allergies. Development of new, and more specifc, second-generation of immunotoxins following proDerp1αS, is further discussedItem Sea anemone actinoporins: The transition from a folded soluble state to a functionally active membrane-bound oligomeric pore(Current Protein and Peptide Science, 2007) Alegre Cebollada, Jorge; Oñaderra, Mercedes; Gavilanes, José G.; Martínez Del Pozo, ÁlvaroActinoporins are a family of 20-kDa, basic proteins isolated from sea anemones, whose activity is inhibited by preincubation with sphingomyelin. They are produced in monomeric soluble form but, when binding to the plasma membrane, they oligomerize to produce functional pores which result in cell lysis. Equinatoxin II (EqtII) from Actinia equina and Sticholysin II (StnII) from Stichodactyla helianthus are the actinoporins that have been studied in more detail. Both proteins display a beta-sandwich fold composed of 10 beta-strands flanked on each side by two short alpha-helices. Twodimensional crystallization on lipid monolayers has allowed the determination of low-resolution models of tetrameric structures distinct from the pore. However, the actual structure of the pore is not known yet. Wild-type EqtII and StnII, as well as a nice collection of natural and artificially made variants of both proteins, have been produced in Escherichia coli and purified. Their characterization has allowed the proposal of a model for the mechanism of pore formation. Four regions of the actinoporins structure seem to play an important role. First, a phosphocholine-binding site and a cluster of exposed aromatic residues, together with a basic region, would be involved in the initial interaction with the membrane, whereas the amphipathic N-terminal region would be essential for oligomerization and pore formation. Accordingly, the model states that pore formation would proceed in at least four steps: Monomer binding to the membrane interface, assembly of four monomers, and at least two distinct conformational changes driving to the final formation of the functional pore.Item Toxin-induced pore formation is hindered by intermolecular hydrogen bonding in sphingomyelin bilayers(Biochimica et Biophysica Acta - Biomembranes, 2016) García Linares, Sara; Palacios Ortega, Juan; Yasuda, Tomokazu; Åstrand, Mia; Gavilanes, José G.; Martínez Del Pozo, Álvaro; Slotte, J. PeterSticholysin I and II (StnI and StnII) are pore-forming toxins that use sphingomyelin (SM) for membrane binding. We examined how hydrogen bonding among membrane SMs affected the StnI- and StnII-induced pore formation process, resulting in bilayer permeabilization. We compared toxin-induced permeabilization in bilayers containing either SM or dihydro-SM (lacking the trans 4 double bond of the long-chain base), since their hydrogen-bonding properties are known to differ greatly. We observed that whereas both StnI and StnII formed pores in unilamellar vesicles containing palmitoyl-SM or oleoyl-SM, the toxins failed to similarly form pores in vesicles prepared from dihydro-PSM or dihydro-OSM. In supported bilayers containing OSM, StnII bound efficiently, as determined by surface plasmon resonance. However, StnII binding to supported bilayers prepared from dihydro-OSM was very low under similar experimental conditions. The association of the positively charged StnII (at pH 7.0) with unilamellar vesicles prepared from OSM led to a concentration-dependent increase in vesicle charge, as determined from zeta-potential measurements. With dihydro-OSM vesicles, a similar response was not observed. Benzyl alcohol, which is a small hydrogen-bonding compound with affinity to lipid bilayer interfaces, strongly facilitated StnII-induced pore formation in dihydro-OSM bilayers, suggesting that hydrogen bonding in the interfacial region originally prevented StnII from membrane binding and pore formation. We conclude that interfacial hydrogen bonding was able to affect the membrane association of StnI- and StnII, and hence their pore forming capacity. Our results suggest that other types of protein interactions in bilayers may also be affected by hydrogen-bonding origination from SMs.Item Characterization of a new toxin from the entomopathogenic fungus Metarhizium anisopliae: the ribotoxin anisoplin(Biological chemistry, 2017) Olombrada, Miriam; Medina, Pilar; Budia, Flor; Gavilanes, José; Martínez Del Pozo, Álvaro; García Ortega, LucíaMetarhizium anisopliae is an entomopathogenic fungus relevant in biotechnology with applications like malaria vector control. Studies of its virulence factors are therefore of great interest. Fungal ribotoxins are toxic ribonucleases with extraordinary efficiency against target ribosomes and suggested as potential insecticides. Here, we describe this ribotoxin characteristic activity in M. anisopliae cultures. Anisoplin has been obtained as a recombinant protein and further characterized. It is structurally similar to hirsutellin A, the ribotoxin from the entomopathogen Hirsutella thompsonii. Moreover, anisoplin shows the ribonucleolytic activity typical of ribotoxins and cytotoxicity against insect cells. How Metarhizium uses this toxin and possible applications are on perspective.Item Role of histidine-50, glutamic acid-96 and histidine-137 in the ribonucleolytic mechanism of the ribotoxin alpha-sarcin(Proteins: Structure, Function and Genetics, 1999) Lacadena García-Gallo, Francisco Javier; Martínez Del Pozo, Álvaro; Martínez Ruiz, Antonio; Pérez-Cañadillas, José Manuel; Bruix, Marta; Mancheño Gómez, José Miguel; Gavilanes Franco, José Gregorio; Oñaderra Sánchez, Mercedesalpha-Sarcin is a ribotoxin secreted by the mold Aspergillus giganteus that degrades the ribosomal RNA by acting as a cyclizing ribonuclease. Three residues potentially involved in the mechanism of catalysis--histidine-50, glutamic acid-96, and histidine-137--were changed to glutamine. Three different single mutation variants (H50Q, E96Q, H137Q) as well as a double variant (H50/137Q) and a triple variant (H50/137Q/E96Q) were prepared and isolated to homogeneity. These variants were spectroscopically (circular dichroism, fluorescence emission, and proton nuclear magnetic resonance) characterized. According to these results, the three-dimensional structure of these variants of alpha-sarcin was preserved; only very minor local changes were detected. All the variants were inactive when assayed against either intact ribosomes or poly(A). The effect of pH on the ribonucleolytic activity of alpha-sarcin was evaluated against the ApA dinucleotide. This assay revealed that only the H50Q variant still retained its ability to cleave a phosphodiester bond, but it did so to a lesser extent than did wild-type alpha-sarcin. The results obtained are interpreted in terms of His137 and Glu96 as essential residues for the catalytic activity of alpha-sarcin (His137 as the general acid and Glu96 as the general base) and His50 stabilizing the transition state of the reaction catalyzed by alpha-sarcin.Item The ribonucleolytic activity of the ribotoxin α-sarcin is not essential for in vitro protein biosynthesis inhibition(BBA-Proteins and Proteomics, 2011) Alvarez García, Elisa; Diago Navarro, Elizabeth; Herrero Galán, Elías; García Ortega, Lucía; López Villarejo, Juan; Olmo López, Nieves; Díaz Orejas, Ramón; Gavilanes, José G.; Martínez Del Pozo, ÁlvaroFungal ribotoxins are toxic secreted ribonucleases that cleave a conserved single phosphodiester bond located at the sarcin/ricin loop of the larger rRNA. This cleavage inactivates ribosomes leading to protein biosynthesis inhibition and cell death. It has been proposed that interactions other than those found at the active site of ribotoxins are needed to explain their exquisite specific activity. The study presented shows the ability of a catalytically inactive α-sarcin mutant (H137Q) to bind eukaryotic ribosomes and interfere with in vitro protein biosynthesis. The results obtained are compatible with previous observations that α-sarcin can promote cell death by a mechanism that is independent of rRNA cleavage, expanding the potential set of activities performed by this family of toxins.- Project number: 117
Item I.amAble: aprendizaje e inclusión educativa mediante talleres científicos(2020) Herrero Domínguez, Santiago; Martínez Del Pozo, Álvaro; Mancheño Real, María José; Osío Barcina, José De Jesús; Nacenta Torres, Pablo; Bárcena Espelleta, Araceli; Rubio Lago, Luis; Álvarez Serrano, Inmaculada; Cortés Gil, Raquel; González Prieto, Rodrigo; Torrecilla Manresa, Sofia; Cilleros Prados, Olga; Sobrino Díaz, María Lourdes; Bartolomé Vílchez, Javier; Cortijo Montes, Miguel; Coloma Manjón-Cabeza, Isabel; Catalán Torrecilla, Cristina; Guerrero Martínez, Andrés; Martínez Madrid, Carmen Belén; Martínez Ruiz, María Paloma; Méndez Pozo, Gonzalo Rubén; Ranchal Sánchez, Rocío; Priego Bermejo, José Luis; Maestre Varea, David; Desvoyes, Bénedicte; Gutiérrez Franco, Yanna María; Arribas Fernández, Paula; Julián Cortés, ÁlvaroI.amAble ha ofrecido a estudiantes universitarios de física, química, veterinaria, biología y educación la oportunidad de complementar su formación mediante el diseño, la realización y la evaluación de talleres científicos que faciliten la inclusión de personas con diversidad cognitiva. Los talleres han sido diseñados por el alumnado universitario de ciencias y perfilados por estudiantes de educación para ser llevados a cabo por alumnado preuniversitario en parejas, de forma que un miembro pertenezca a un centro de secundaria ordinario y el otro miembro a un centro de educación especial. Aquellos talleres que se han considerado más adecuados por su adaptabilidad se han llevado a la práctica guiados por estudiantes de ciencias y de educación. Los miembros del proyecto, que incluyen representantes de todos los estamentos universitarios, han supervisado todas las tareas descritas anteriormente. Además de los miembros de la Universidad Complutense, también figuran personas voluntarias de otras instituciones científicas y educativas. El alumnado universitario ha tenido la posibilidad, no sólo de asentar y profundizar algunos contenidos científicos o poner en práctica algunas de las enseñanzas adquiridas, sino también de desarrollar su empatía, su capacidad de comunicar e improvisar y de adaptarse a un público heterogéneo. Ello ha mejorado sus perspectivas laborales, especialmente dentro de la educación formal e informal (animación sociocultural, museos científicos...). Además, han contribuido a facilitar la inclusión educativa de las personas con diversidad funcional y a mejorar la cultura científica de la sociedad. Con este proyecto, inspirado en la metodología Aprendizaje-Servicio (ApS), se ha pretendido también mejorar la accesibilidad a las experiencias y contenidos científicos y facilitar la inclusión educativa de las personas con diversidad funcional, especialmente diversidad cognitiva o intelectual. En la primera edición de I.amAble (2016-17) se hizo hincapié en el diseño y selección de fichas para hacer talleres (aunque también se realizaron talleres). En la segunda edición (2017-18) se puso un mayor énfasis en llevar los talleres a un mayor número de centros educativos. En la pasada edición (2018-19) se puso el acento en los procesos de evaluación. En esta cuarta edición (2019-20), se han seguido trabajando y puliendo todos esos aspectos, pero se ha priorizado la transformación de I.amAble en un proyecto de tipo aprendizaje-servicio, integrándolo en asignaturas formales, concretamente en Complementos de Física y Complementos de Química, del Máster en Formación de Profesorado, en la especialidad de Física y Química. Item Secretion of Recombinant Pro- and Mature Fungal α-Sarcin Ribotoxin by the Methylotrophic YeastPichia pastoris:The Lys–Arg Motif Is Required for Maturation(Protein Expression and Purification, 1998) Martínez Ruiz, Antonio; Martínez Del Pozo, Álvaro; Lacadena García-Gallo, Francisco Javier; Mancheño Gómez, José Miguel; Oñaderra Sánchez, Mercedes; Carlos López-Otı́n; Gavilanes Franco, José Gregorioα-Sarcin is a ribosome-inactivating protein from the moldAspergillus giganteus.The methylotrophic yeastPichia pastorishas been transformed with two plasmids (pHILD2preαS and pHILS1preαS), which contain the complete α-sarcin cDNA, including its original fungal leader peptide, under the control of yeast alcohol oxidase promoter. The second one is indeed fused to the signal sequence ofP. pastorisacid phosphatase. The transformed yeasts secreted both mature and pro-α-sarcin. The presence of this pro-α-sarcin in the yeast extracellular medium is due to an inefficient recognition of the pro-sequence by a putative Kex2p-like endopeptidase. A third plasmid accounting for a single mutation of the α-sarcin leader peptide was designed to produce a more efficient Kex2p recognition motif. This approach resulted in the extracellular production of only the mature protein, suggesting the existence of a two-step mechanism for processing its leader peptide. This recombinant α-sarcin is identical to the original fungal protein, according to activity and spectroscopic criteria. In addition, pro-α-sarcin, which has been characterized for the first time, also exhibits ribonucleolytic activity as the mature protein does. Therefore, protection of the producing cells against this kind of ribotoxins may depend on an efficient recognition of the signal sequence followed by translocation of the nascent polypeptide to the endoplasmic reticulum.Item Structure-activity relationship of α mating pheromone from the fungal pathogen Fusarium oxysporum(Journal of Biological Chemistry, 2017) Vitale, Stefania; Partida Hanon, Angelica; Serrano, Soraya; Martínez Del Pozo, Álvaro; Di Pietro, Antonio; Turrà, David; Bruix, MartaDuring sexual development, ascomycete fungi produce two types of peptide pheromones termed a and α. The α pheromone from the budding yeast Saccharomyces cerevisiae, a thirteen residue peptide which elicits cell cycle arrest and chemotropic growth, has served as paradigm for the interaction of small peptides with their cognate G protein-coupled receptors (GPCRs). However, no structural information is currently available for α pheromones from filamentous ascomycetes, which are significantly shorter and share almost no sequence similarity with the S. cerevisiae homolog. High-resolution structure of synthetic α-pheromone from the plant pathogenic ascomycete Fusarium oxysporum revealed the presence of a central β-turn resembling that of its yeast counterpart. Disruption of the fold by Dalanine substitution of the conserved central Gly6-Gln7 residues or by random sequence scrambling demonstrated a crucial role for this structural determinant in chemoattractant activity. Unexpectedly, the growth inhibitory effect of F. oxysporum α-pheromone was independent of the cognate GPCR Ste2 and of the central β-turn but instead required two conserved Trp1-Cys2 residues at the N-terminus. These results indicate that, in spite of their reduced size, fungal α-pheromones contain discrete functional regions with a defined secondary structure that regulate diverse biological processes such as polarity reorientation and cell division.Item Role of the Tryptophan Residues in the Specific interaction of the Sea Anemone Stichodacty la helianthus’s Actinoporin Sticholysin II with Biological Membranes(Biochemistry, 2016) García Linares, Sara; Maula, Terhi; Rivera de la Torre, Esperanza; Gavilanes, José G.; Slotte, J.Peter; Martínez Del Pozo, ÁlvaroActinoporins are pore-forming toxins from sea anemones. Upon interaction with sphingomyelin-containing bilayers, they become integral oligomeric membrane structures that form a pore. Sticholysin II from Stichodactyla helianthus contains five tryptophans located at strategic positions; its role has now been studied using different mutants. Results show that W43 and W115 play a eterminant role in maintaining the high thermostability of the protein, while W146 provides specific interactions for protomer−protomer assembly. W110 and W114 sustain the hydrophobic effect, which is one of the major driving forces for membrane binding in the presence of Chol. However, in its absence, additional interactions with sphingomyelin are required. These conclusions were confirmed with two sphingomyelin analogues, one of which had impaired hydrogen bonding properties. The results obtained support actinoporins’ Trp residues playing a major role in membrane recognition and binding, but their residues have an only minor influence on the diffusion and oligomerization steps needed to assemble a functional pore.