Person: Martínez Ruiz, Antonio
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First Name
Antonio
Last Name
Martínez Ruiz
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Farmacia
Department
Bioquímica y Biología Molecular
Area
Bioquímica y Biología Molecular
Identifiers
14 results
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Item Ribotoxins are a more widespread group of proteins within the filamentous fungi than previously believed(Toxicon, 1999) Martínez Ruiz, Antonio; Richard Kao; Julian Davies; Martínez Del Pozo, Álvaroa-Sarcin, restrictocin and mitogillin are the best known members of the family of fungal ribotoxins. In recent years, new members of this family have been discovered and characterised. In this work, we study the occurrence of ribotoxins among di erent species of fungi. The presence of ribotoxins has been identi®ed in some new species by means of genetic studies, as well as expression and activity assays. The ribotoxin genes have been partially sequenced, and demonstrate a high degree of similarity. These studies demonstrate that these toxins are more widespread than previously considered. This is surprising, considering the ribotoxins are such speci®c and potent toxins, of unknown biological function. These studies con®rm the hypothesis that these proteins are naturally engineered toxins derived from ribonucleases of broad substrate speci®city.Item Endothelial nitric oxide synthase regulates N-Ras activation on the Golgi complex of antigen-stimulated T cells(2008) Ibiza, Sales; Pérez-Rodríguez, Andrea; Ortega, Ángel; Martínez Ruiz, Antonio; Barreiro, Olga; Carlota A. García-Domínguez; Víctor M. Víctor; Juan V. Esplugues; José M. Rojas; Francisco Sánchez-Madrid; Juan M. SerradorRas/ERK signaling plays an important role in T cell activation and development. We recently reported that endothelial nitric oxide synthase (eNOS)-derived NO regulates T cell receptor (TCR)- dependent ERK activation by a cGMP-independent mechanism. Here, we explore the mechanisms through which eNOS exerts this regulation. We have found that eNOS-derived NO positively regulates Ras/ERK activation in T cells stimulated with antigen on antigenpresenting cells (APCs). Intracellular activation of N-, H-, and K-Ras was monitored with fluorescent probes in T cells stably transfected with eNOS-GFP or its G2A point mutant, which is defective in activity and cellular localization. Using this system, we demonstrate that eNOS selectively activates N-Ras but not K-Ras on the Golgi complex of T cells engaged with APC, even though Ras isoforms are activated in response to NO from donors. We further show that activation of N-Ras involves eNOS-dependent S-nitrosylation on Cys118, suggesting that upon TCR engagement, eNOS-derived NO directly activates N-Ras on the Golgi. Moreover, wild-type but not C118S N-Ras increased TCR-dependent apoptosis, suggesting that S-nitrosylation of Cys118 contributes to activation-induced T cell death. Our data define a signaling mechanism for the regulation of the Ras/ERK pathway based on the eNOS-dependent differential activation of N-Ras and K-Ras at specific cell compartments.Item The cytotoxin α‐sarcin behaves as a cyclizing ribonuclease(FEBS Letters, 1998) Lacadena García-Gallo, Francisco Javier; Martínez Del Pozo, Álvaro; Valle Lacadena; Martínez Ruiz, Antonio; Mancheño Gómez, José Miguel; Oñaderra Sánchez, Mercedes; Gavilanes Franco, José GregorioThe hydrolysis of adenylyl(3PC5P)adenosine (ApA) and guanylyl(3PC5P)adenosine (GpA) dinucleotides by the cytotoxic protein K-sarcin has been studied. Quantitative analysis of the reaction has been performed through reversephase chromatographic (HPLC) separation of the resulting products. The hydrolysis of the 3P-5P phosphodiester bond of these substrates yields the 2P-3P cyclic mononucleotide; this intermediate is converted into the corresponding 3P-monophosphate derivative as the final product of the reaction. The values of the apparent Michaelis constant (KM), kcat and kcat/ KM have also been calculated. The obtained results fit into a twostep mechanism for the enzymatic activity of K-sarcin and allow to consider this protein as a cyclizing RNase. z 1998 Federation of European Biochemical Societies.Item Signalling by NO-induced protein S-nitrosylation and S-glutathionylation: Convergences and divergences(Cardiovascular research, 2007) Martínez Ruiz, Antonio; Lamas, SantiagoThe role of nitric oxide in several signalling routes has been clearly established. In recent years increasing attention has been paid to its ability to produce covalent protein post-translational modifications in conjunction with other reactive oxygen and nitrogen species. Among these, the modification of cysteine residues has been shown to be of particular importance due to the functional relevance of many of them. In this review, we focus on the modification of the cysteine thiol by incorporation of a NO moiety (S-nitrosylation) or of a glutathione moiety (S-glutathionylation). Both modifications are produced by different reactions induced by nitric oxide-related species. We discuss the differences and similarities of both modifications, and their relationships, in regard to the biochemical mechanisms that produce them, including the enzymatic activities that may catalyze some of them and their subcellular compartmentalization. Even when biochemical knowledge is one step ahead of the demonstration of their pathophysiological relevance, we also describe the potential role of both modifications in several processes in which both post-translational modifications are involved. © 2007 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.Item Nitric Oxide Down-regulates Caveolin-3 Levels through the Interaction with Myogenin, Its Transcription Factor(Journal of biological chemistry, 2007) Martínez-Moreno, Mónica; Martínez Ruiz, Antonio; Álvarez-Barrientos, Alberto; Gavilanes Franco, Francisco; Lamas, Santiago; Rodríguez Crespo, José IgnacioCertain patients suffering from chronic diseases such as AIDS or cancer experience a constant cellular secretion of tumor necrosis factor and other pro-inflammatory cytokines that results in a continuous release of nitric oxide ( NO) to the bloodstream. One immediate consequence of the deleterious action of NO is weight loss and the progressive destruction of muscular mass in a process known as cachexia. We have previously reported that caveolin-3, a specific marker of muscle cells, becomes down-regulated by the action of NO on muscular myotubes. We describe herein that the changes observed in caveolin-3 levels are due to the alteration of the DNA binding activity of the muscular transcription factor myogenin. In the presence of NO, the binding of transcription factors from cell nuclear extracts of muscular tissues to the E boxes present in the caveolin-3 promoter become substantially reduced.When we purified recombinant myogenin and treated it with NO donors, we could detect its S-nitrosylation by three independent methods, suggesting that very likely one of the cysteine residues of the molecule is being modified. Given the role of myogenin as a regulatory protein that determines the level of multiple muscle genes expressed during late myogenesis, our results might represent a novel mode of regulation of muscle development under conditions of nitric oxide-mediated toxicity.Item Functional interplay between endothelial nitric oxide synthase and membrane type 1–matrix metalloproteinase in migrating endothelial cells(Blood, 2007) Genís, Laura; Gonzalo, Pilar; Tutor, Antonio S.; Gálvez, Beatriz G.; Martínez Ruiz, Antonio; Zaragoza, Carlos; Lamas, Santiago; Tryggvason, Karl; Apte, Suneel S.; Arroyo, Alicia G.Nitric oxide (NO) is essential for vascular homeostasis and is also a critical modulator of angiogenesis; however, the molecular mechanisms of NO action during angiogenesis remain elusive. We have investigated the potential relationship between NO and membrane type 1–matrix metalloproteinase (MT1-MMP) during endothelial migration and capillary tube formation. Endothelial NO synthase (eNOS) colocalizes with MT1-MMP at motilityassociated structures in migratory human endothelial cells (ECs); moreover, NO is produced at these structures and is released into the medium during EC migration. We have therefore addressed 2 questions: (1) the putative regulation of MT1-MMP by NO in migratory ECs; and (2) the requirement for MT1-MMP in NOinduced EC migration and tube formation. NO upregulates MT1-MMP membrane clustering on migratory human ECs, and this is accompanied by increased degradation of type I collagen substrate. MT1-MMP membrane expression and localization are impaired in lung ECs from eNOS-deficient mice, and these cells also show impaired migration and tube formation in vitro. Inhibition of MT1-MMP with a neutralizing antibody impairs NOinduced tube formation by human ECs, and NO-induced endothelial migration and tube formation are impaired in lung ECs from mice deficient in MT1-MMP. MT1-MMP thus appears to be a key molecular effector of NO during the EC migration and angiogenic processes, and is a potential therapeutic target for NO-associated vascular disorders.Item S-nitrosylation: a potential new paradigm in signal transduction(Cardiovascular Research, 2004) Martínez Ruiz, Antonio; Lamas, SantiagoMuch attention has been paid to nitric oxide (NO) research since its discovery as a physiological mediator in the cardiovascular system. In recent years, newer roles have been attributed to this molecule and its close relatives, termed collectively reactive nitrogen species (RNS). These roles relate to different mechanisms of protein modification, among which S-nitrosylation of cysteines has emerged as a potential new paradigm in signal transduction and regulation of protein function. We review here the chemical basis of this modification compared with other protein modifications related to nitric oxide, as well as the kind of specificity we can expect from it. We also review the current methodologies that can be applied to the study of S-nitrosylation and identification of S-nitrosylated proteins in cells, and detail the relevance of this modification in several proteins related to cardiovascular system.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 Characterization of a natural larger form of the antifungal protein (AFP) from Aspergillus giganteus(Biochim Biophys Acta, 1997) Martínez Ruiz, Antonio; Martínez Del Pozo, Álvaro; Lacadena García-Gallo, Francisco Javier; Mancheño Gómez, José Miguel; Oñaderra Sánchez, Mercedes; Gavilanes Franco, José GregorioTwo major proteins, a-sarcin and an antifungal polypeptide AFP , are secreted by the mould Ž . Aspergillus giganteus MDH 18894 when it is cultured for 70–80 h. A third major protein is also found in the extracellular medium at 48–60 h, but it disappears as the culture proceeds. This protein has been isolated and characterized in terms of apparent molecular mass, electrophoretic and chromatographic behaviour, NH -terminal primary structure, amino acid content, spectroscopical 2 features, reactivity against anti-AFP antibodies, and antifungal activity. Based on the obtained results it would be an extracellular inactive precursor form of AFP, designated as the large form of AFP lf-AFP . Its amino acid composition is Ž . identical to that of AFP but containing six extra residues. NH -terminal sequence analysis of the first eight amino acid 2 residues of this polypeptide revealed that the extra residues can be perfectly accommodated within the DNA-deduced sequence of the precursor form of AFP. Its alignment with precursor sequences of different proteins, secreted by a variety of Aspergillus spp., reveals the existence of a common tetrapeptide at the carboxy-terminal end of their leader peptides. This sequence would be IlerLeu-Xaa-Yaa-Arg, being mostly Xaa and Yaa an acid residue Asp Ž . rGlu and alanine, respectively. The presence of lf-AFP as an extracellular protein would be in perfect agreement with the existence of this tetrapeptide motif, that can be involved in the protein secretion mechanisms of filamentous fungi.Item A “fluorescence switch” technique increases the sensitivity of proteomic detection and identification of S‐nitrosylated proteins(Proteomics, 2009) Tello, Daniel; Tarín, Carlos; Ahicart, Patricia; Bretón‐Romero, Rosa; Lamas, Santiago; Martínez Ruiz, AntonioProtein S-nitrosylation is a reversible post-translational modification of protein cysteines that is increasingly being considered as a signal transduction mechanism. The ‘‘biotin switch’’ technique marked the beginning of the study of the S-nitrosoproteome, based on the specific replacement of the labile S-nitrosylation by a more stable biotinylation that allowed further detection and purification. However, its application for proteomic studies is limited by its relatively low sensitivity. Thus, typical proteomic experiments require high quantities of protein extracts, which precludes the use of this method in a number of biological settings. We have developed a ‘‘fluorescence switch’’ technique that, when coupled to 2-DE proteomic methodologies, allows the detection and identification of S-nitrosylated proteins by using limited amounts of starting material, thus significantly improving the sensitivity. We have applied this methodology to detect proteins that become S-nitrosylated in endothelial cells when exposed to S-nitroso-L-cysteine, a physiological S-nitrosothiol, identifying already known S-nitrosylation targets, as well as proteins that are novel targets. This ‘‘fluorescence switch’’ approach also allowed us to identify several proteins that are denitrosylated by thioredoxin in cytokine-activated RAW264.7 (murine macrophage) cells. We believe that this method represents an improvement in order to approach the identification of S-nitrosylated proteins in physiological conditions.