Person: García Ortega, Lucía
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First Name
Lucía
Last Name
García Ortega
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Bioquímica y Biología Molecular
Area
Bioquímica y Biología Molecular
Identifiers
17 results
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Now showing 1 - 10 of 17
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 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.Item The ribotoxin -sarcin can cleave the sarcin/ricin loop on late 60S pre-ribosomes(Nucleic Acids Research, 2020) Olombrada, Miriam; Peña, Cohue; Rodríguez Galán, Olga; Klingauf Nerurkar, Purnima; Portugal Calisto, Daniela; Oborská Oplová, Michaela; Altvater, Martin; Gavilanes, José G.; Martínez Del Pozo, Álvaro; Cruz, Jesús de la; García Ortega, Lucía; Govind Panse, VikramThe ribotoxin -sarcin belongs to a family of ribonucleases that cleave the sarcin/ricin loop (SRL), a critical functional rRNA element within the large ribosomal subunit (60S), thereby abolishing translation. Whether -sarcin targets the SRL only in mature 60S subunits remains unresolved. Here, we show that, in yeast, -sarcin can cleave SRLs within late 60S pre-ribosomes containing mature 25S rRNA but not nucleolar/nuclear 60S pre-ribosomes containing 27S pre-rRNA in vivo. Conditional expression of -sarcin is lethal, but does not impede early pre-rRNA processing, nuclear export and the cytoplasmic maturation of 60S pre-ribosomes. Thus, SRL-cleaved containing late 60S pre-ribosomes seem to escape cytoplasmic proofreading steps. Polysome analyses revealed that SRL-cleaved 60S ribosomal subunits form 80S initiation complexes, but fail to progress to the step of translation elongation. We suggest that the functional integrity of a -sarcin cleaved SRL might be assessed only during translation.Item The behaviour of sea anemone actinoporins at the water-membrane interface(Biochimica et Biophysica Acta - Biomembranes, 2011) García Ortega, Lucía; Alegre Cebollada, Jorge; García Linares, Sara; Bruix, Marta; Martínez Del Pozo, Álvaro; Gavilanes, José G.Actinoporins constitute a group of small and basic α-pore forming toxins produced by sea anemones. They display high sequence identity and appear as multigene families. They show a singular behaviour at the water-membrane interface: In aqueous solution, actinoporins remain stably folded but, upon interaction with lipid bilayers, become integral membrane structures. These membranes contain sphingomyelin, display phase coexistence, or both. The water soluble structures of the actinoporins equinatoxin II (EqtII) and sticholysin II (StnII) are known in detail. The crystalline structure of a fragaceatoxin C (FraC) nonamer has been also determined. The three proteins fold as a β-sandwich motif flanked by two α-helices, one of them at the N-terminal end. Four regions seem to be especially important: A cluster of aromatic residues, a phosphocholine binding site, an array of basic amino acids, and the N-terminal α-helix. Initial binding of the soluble monomers to the membrane is accomplished by the cluster of aromatic amino acids, the array of basic residues, and the phosphocholine binding site. Then, the N-terminal α-helix detaches from the β-sandwich, extends, and lies parallel to the membrane. Simultaneously, oligomerization occurs. Finally, the extended N-terminal α-helix penetrates the membrane to build a toroidal pore. This model has been however recently challenged by the cryo-EM reconstruction of FraC bound to phospholipid vesicles. Actinoporins structural fold appears across all eukaryotic kingdoms in other functionally unrelated proteins. Many of these proteins neither bind to lipid membranes nor induce cell lysis. Finally, studies focusing on the therapeutic potential of actinoporins also abound.Item Characterization of a new toxin from the entomopathogenic fungus Metarhizium anisopliae: the ribotoxin anisoplin(Biological Chemistry, 2016) Olombrada, Miriam; Medina, Pilar; Budia, Flor; Gavilanes, José G.; 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 Fungal Ribotoxins(ELS, 2018) García Ortega, Lucía; Palacios Ortega, Juan; Martínez Del Pozo, ÁlvaroFungal ribotoxins constitute a family of extracellular ribonucleases with exquisite specificity against rRNA (ribonucleic acid). They induce apoptotic death of cells after inhibiting protein translation. Ribosomes become functionally incompetent because ribotoxins cleave one single phosphodiester bond, located at a unique and universally conserved loop, needed for elongation factors function. As secreted proteins, ribotoxins need to cross the membrane of their target cells in order to exert their catalytic activity, and they do it without receptor mediation. Using lipid model systems, it has been shown that they are able to enter cells with membranes enriched in acidic phospholipids. Both membrane-interacting and ribosomal-recognition activities are characterised by distinct structural features. Even though the natural function of ribotoxins is not known yet, their production by entomopathogenic fungi has suggested their insecticidal role. After decades of detailed study, the biotechnological potential of ribotoxins in pest control and as antitumour agents is becoming evident.Item Fungal extracellular ribotoxins as insecticidal agents(Insect Biochemistry and Molecular Biology, 2013) Olombrada Sacristán, Miriam; Herrero Galán, Elías; Tello, Daniel; Oñaderra Sánchez, Mercedes; Gavilanes, José G.; Martínez Del Pozo, Álvaro; García Ortega, LucíaFungal ribotoxins were discovered almost 50 years ago as extracellular ribonucleases (RNases) with antitumoral properties. However, the biological function of these toxic proteins has remained elusive. The discovery of the ribotoxin HtA, produced by the invertebrates pathogen H. thompsonii, revived the old proposal that insecticidal activity would be their long searched function. Unfortunately, HtA is rather singular among all ribotoxins known in terms of sequence and structure similarities. Thus, it was intriguing to answer the question of whether HtA is just an exception or, on the contrary, the paradigmatic example of the ribotoxins function. The work presented uses HtA and -sarcin, the most representative member of the ribotoxins family, to show their strong toxic action against insect larvae and cells.- Project number: 326
Item Hacia una Universidad Complutense más diversa: actividades de visibilización del colectivo LGTBI en las Facultades de Químicas y Biológicas(2022) Rodríguez Crespo, José Ignacio; García Ortega, Lucía; Guzmán Pastor, Manuel; Narbona Corral, Javier; Gutiérrez Carmona, Adrián; Arauco Arteche, Iñigo; Ballesteros Sanabria, Laura; Castromil Benito, Estela Soraya; Amigot Sánchez, Rafael; Cueto Remacha, Mateo; Martín Migallón, Guillermo Item Pulmonary surfactant-derived antiviral actions at the respiratory surface(Current Opinion in Colloid & Interface Science, 2023) Isasi Campillo, Miriam; Losada Oliva, Paula; Pérez Gil, Jesús; Olmeda Lozano, Bárbara; García Ortega, LucíaLung surfactant (LS) is a membrane-based lipid-protein complex that lines the alveoli, reducing the surface tension at the air-liquid interface and thus minimizing the work of breathing. Besides this function, LS is also the first physical barrier between the outside air and the systemic circulation, therefore playing a key role in the defense against harmful particles and microorganisms. Viral respiratory tract infections (RTIs), and especially acute lower RTIs, are one of the leading causes of morbidity and mortality worldwide. LS participates in the network of interactions between viruses and the immune system to prevent or lessen the effects of the infection, but it is also altered by these pathogens, which can potentially impair its function. The aim of this review is to provide an integrated multidisciplinary overview toward understanding the interplay between respiratory viruses and LS and its health impact on the respiratory system. The review is centered on the antiviral mechanisms of both LS proteins and lipids, and their different interactions that lead to varying outcomes. Finally, a summary of the clinical application of surfactant in the scene of lung viral infection is disclosed, including state-of-the-art approaches of the therapeutic use of surfactant components.Item The ribotoxin α-sarcin can cleave the sarcin/ricin loop on late 60S pre-ribosomes(Nucleic Acids Research, 2020) Olombrada, Miriam; Peña, Cohue; Rodríguez Galán, Olga; Klingauf Nerurkar, Purnima; Portugal Calisto, Daniela; Oborská Oplová, Michaela; Altvater, Martin; Gavilanes, José G.; Martínez Del Pozo, Álvaro; De la Cruz, Jesús; García Ortega, Lucía; Govind Panse, VikramThe ribotoxin -sarcin belongs to a family of ribonucleases that cleave the sarcin/ricin loop (SRL), a critical functional rRNA element within the large ribosomal subunit (60S), thereby abolishing translation. Whether -sarcin targets the SRL only in mature 60S subunits remains unresolved. Here, we show that, in yeast, -sarcin can cleave SRLs within late 60S pre-ribosomes containing mature 25S rRNA but not nucleolar/nuclear 60S pre-ribosomes containing 27S pre-rRNA in vivo. Conditional expression of -sarcin is lethal, but does not impede early pre-rRNA processing, nuclear export and the cytoplasmic maturation of 60S pre-ribosomes. Thus, SRL-cleaved containing late 60S pre-ribosomes seem to escape cytoplasmic proofreading steps. Polysome analyses revealed that SRL-cleaved 60S ribosomal subunits form 80S initiation complexes, but fail to progress to the step of translation elongation. We suggest that the functional integrity of a -sarcin cleaved SRL might be assessed only during translation.