(FBIOyF) Departamento de Química Orgánica - Artículos
URI permanente para esta colección
Examinar
Examinando (FBIOyF) Departamento de Química Orgánica - Artículos por Fecha de publicación
Mostrando 1 - 20 de 108
Resultados por página
Opciones de ordenación
Ítem Acceso Abierto Identification and physiological characterization of phosphatidic acid phosphatase enzymes involved in triacylglycerol biosynthesis in Streptomyces coelicolor(BMC, 2013-01-29) Comba, Santiago; Menendez Bravo, Simón M.; Arabolaza, Ana Lorena; Gramajo, Hugo CesarBackground: Phosphatidic acid phosphatase (PAP, EC 3.1.3.4) catalyzes the dephosphorylation of phosphatidate yielding diacylglycerol (DAG), the lipid precursor for triacylglycerol (TAG) biosynthesis. Despite the importance of PAP activity in TAG producing bacteria, studies to establish its role in lipid metabolism have been so far restricted only to eukaryotes. Considering the increasing interest of bacterial TAG as a potential source of raw material for biofuel production, we have focused our studies on the identification and physiological characterization of the putative PAP present in the TAG producing bacterium Streptomyces coelicolor. Results: We have identified two S. coelicolor genes, named lppα (SCO1102) and lppβ (SCO1753), encoding for functional PAP proteins. Both enzymes mediate, at least in part, the formation of DAG for neutral lipid biosynthesis. Heterologous expression of lppα and lppβ genes in E. coli resulted in enhanced PAP activity in the membrane fractions of the recombinant strains and concomitantly in higher levels of DAG. In addition, the expression of these genes in yeast complemented the temperature-sensitive growth phenotype of the PAP deficient strain GHY58 (dpp1lpp1pah1). In S. coelicolor, disruption of either lppα or lppβ had no effect on TAG accumulation; however, the simultaneous mutation of both genes provoked a drastic reduction in de novo TAG biosynthesis as well as in total TAG content. Consistently, overexpression of Lppα and Lppβ in the wild type strain of S. coelicolor led to a significant increase in TAG production. Conclusions: The present study describes the identification of PAP enzymes in bacteria and provides further insights on the genetic basis for prokaryotic oiliness. Furthermore, this finding completes the whole set of enzymes required for de novo TAG biosynthesis pathway in S. coelicolor. Remarkably, the overexpression of these PAPs in Streptomyces bacteria contributes to a higher productivity of this single cell oil. Altogether, these results provide new elements and tools for future cell engineering for next-generation biofuels production.Ítem Acceso Abierto Structural requirements for the antifungal activities of natural drimane sesquiterpenes and analogues, supported by conformational and electronic studies(MDPI, 2013-02-05) Derita, Marcos Gabriel; Montenegro, Iván; Garibotto, Francisco; Enriz, Ricardo Daniel; Cuellar Fritis, Mauricio; Zacchino, Susana; https://orcid.org/0000-0002-7112-5500Seventeen drimanes including polygodial (1), isopolygodial (2), drimenol (3) and confertifolin (4) obtained from natural sources and the semi-synthetic derivatives 5–17 obtained from 1–3, were evaluated in vitro for antifungal properties against a unique panel of fungi with standardized procedures by using two end-points, MIC100 and MIC50. A SAR analysis of the whole series, supported by conformational and electronic studies, allowed us to show that the Δ7,8 -double bond would be one of the key structural features related to the antifungal activity. The MEPs obtained for active compounds exhibit a clear negative minimum value (deep red zone) in the vicinity of the Δ7,8 -double bond, which is not present in the inactive ones. Apart of this negative zone, a positive region (deep blue) appears in 1, which is not observed either in its epimer 2 nor in the rest of the active compounds. The LogP of active compounds varies between 2.33 and 3.84, but differences in MICs are not correlated with concomitant variations in LogP values.Ítem Acceso Abierto Synthesis, Bioevaluation and Structural Study of Substituted Phthalazin-1(2H)-ones Acting as Antifungal Agents(MDPI Open Access Publishing, 2013-03) Derita, Marcos Gabriel; Del Olmo, Esther; Barboza, Bianca; García Cadenas, Ana E.; López Pérez, José L.; Andújar, Sebastián; Enriz, Ricardo Daniel; Zacchino, Susana; San Feliciano, ArturoTwenty-five polysubstituted phthalazinone derivatives were synthesized and tested for their antifungal activity against a panel of pathogenic and clinically important yeasts and filamentous fungi. Among them, the compound 4-(4-chlorobenzyl)-2- methylphthalazin-1(2H)-one (5) exhibited a remarkable antifungal activity against standardised strains of dermatophytes and Cryptococcus neoformans, as well as against some clinical isolates. A physicochemical study performed on compound 5 revealed its conformational and electronic characteristics, providing us with useful data for the future design of novel related antifungal analogues.Ítem Acceso Abierto An introductory classroom exercise on protein molecular model visualization and detailed analysis of protein–ligand binding(Wiley, 2013-03-23) Poeylaut-Palena, Andrés A.; Laborde, María de los ÁngelesA learning module for molecular level analysis of protein structure and ligand/drug interaction through the visualization of X-ray diffraction is presented. Using DeepView as molecular model visualization software, students learn about the general concepts of protein structure. This Biochemistry classroom exercise is designed to be carried out by following the detailed instructions that make software handling straightforward. Students learn about protein structure and gain insight into the molecular level of the interaction of two active compounds with their receptor.Ítem Acceso Abierto Effects of Chirality on the Antifungal Potency of Methylated Succinimides Obtained by Aspergillus fumigatus Biotransformations. Comparison with Racemic Ones(MDPI Open Access Publishing, 2013-05-15) Sortino, Maximiliano Andrés ; Postigo, Agustina; Zacchino, SusanaEighteen (3R) and (3R,4R)-N-phenyl-, N-phenylalkyl and N-arylsuccinimides were prepared with high enantioselectivity by biotransformation of maleimides with A. fumigatus. This environmentally friendly, clean and economical procedure was performed by the whole-cell fungal bioconversion methodology. Their corresponding eighteen racemic succinimides were prepared instead by synthetic methods. Both, the racemic and the chiral succinimides were tested simultaneously by the microbroth dilution method of CLSI against a panel of human opportunistic pathogenic fungi of clinical importance. Chiral succinimides showed higher antifungal activity than the corresponding racemic ones and the differences in activity were established by statistical methods. The bottlenecks for developing chiral drugs are how to obtain them through a low-cost procedure and with high enantiomeric excess. Results presented here accomplish both these objectives, opening an avenue for the development of asymmetric succinimides as new antifungal drugs for pharmaceutical use.Ítem Acceso Abierto The type III protein secretion system contributes to Xanthomonas citri subsp. citri biofilm formation(Springer Nature, 2014-04-18) Zimaro, Tamara; Sgro, Germán Gustavo; Garofalo, Cecilia Graciela; Ficarra, Florencia Andrea; Ottado, Jorgelina; Gottig, Natalia; Thomas, Ludivine; Marondedze, Claudius; Gehring, ChrisBackground: Several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a Type III protein secretion system (T3SS). The role of T3SS in bacterial pathogenesis is well established but whether this system is involved in multicellular processes, such as bacterial biofilm formation has not been elucidated. Here, the phytopathogen Xanthomonas citri subsp. citri (X. citri) was used as a model to gain further insights about the role of the T3SS in biofilm formation. Results: The capacity of biofilm formation of different X. citri T3SS mutants was compared to the wild type strain and it was observed that this secretion system was necessary for this process. Moreover, the T3SS mutants adhered proficiently to leaf surfaces but were impaired in leaf-associated growth. A proteomic study of biofilm cells showed that the lack of the T3SS causes changes in the expression of proteins involved in metabolic processes, energy generation, exopolysaccharide (EPS) production and bacterial motility as well as outer membrane proteins. Furthermore, EPS production and bacterial motility were also altered in the T3SS mutants. Conclusions: Our results indicate a novel role for T3SS in X. citri in the modulation of biofilm formation. Since this process increases X. citri virulence, this study reveals new functions of T3SS in pathogenesis.Ítem Acceso Abierto Pleiotropic effect of AccD5 and AccE5 depletion in acyl-coenzyme a carboxylase activity and in lipid biosynthesis in mycobacteria(Public Library of Science, 2014-06-20) Bazet Lyonnet, Bernardo; Diacovich, Lautaro; Cabruja, Matías Ezequiel; Bardou, Fabienne; Quémard, Annaïk; Gago, Gabriela; Gramajo, Hugo CesarMycobacteria contain a large variety of fatty acids which are used for the biosynthesis of several complex cell wall lipids that have been implicated in the ability of the organism to resist host defenses. The building blocks for the biosynthesis of all these lipids are provided by a fairly complex set of acyl-CoA carboxylases (ACCases) whose subunit composition and roles within these organisms have not yet been clearly established. Previous biochemical and structural studies provided strong evidences that ACCase 5 from Mycobacterium tuberculosis is formed by the AccA3, AccD5 and AccE5 subunits and that this enzyme complex carboxylates acetyl-CoA and propionyl-CoA with a clear substrate preference for the latest. In this work we used a genetic approach to unambiguously demonstrate that the products of both accD5 and accE5 genes are essential for the viability of Mycobacterium smegmatis. By obtaining a conditional mutant on the accD5-accE5 operon, we also demonstrated that the main physiological role of this enzyme complex was to provide the substrates for fatty acid and mycolic acid biosynthesis. Furthermore, enzymatic and biochemical analysis of the conditional mutant provided strong evidences supporting the notion that AccD5 and/or AccE5 have an additional role in the carboxylation of long chain acylCoA prior to mycolic acid condensation. These studies represent a significant step towards a better understanding of the roles of ACCases in mycobacteria and confirm ACCase 5 as an interesting target for the development of new antimycobacterial drugs.Ítem Acceso Abierto New chiral 1,2-aminoalcohols derived from biomass and their application in diethyl zinc additions(Elsevier, 2014-10-15) Zanardi, María Marta; Botta, María Celeste; Suárez, Alejandra GracielaÍtem Acceso Abierto Engineering a Streptomyces coelicolor biosynthesis pathway into Escherichia coli for high yield triglyceride production(BMC, 2014-12) Comba, Santiago; Sabatini, Martín; Menendez Bravo, Simón M.; Arabolaza, Ana Lorena; Gramajo, Hugo CesarBackground: Microbial lipid production represents a potential alternative feedstock for the biofuel and oleochemical industries. Since Escherichia coli exhibits many genetic, technical, and biotechnological advantages over native oleaginous bacteria, we aimed to construct a metabolically engineered E. coli strain capable of accumulating high levels of triacylglycerol (TAG) and evaluate its neutral lipid productivity during high cell density fed-batch fermentations. Results: The Streptomyces coelicolor TAG biosynthesis pathway, defined by the acyl-CoA:diacylglycerol acyltransferase (DGAT) Sco0958 and the phosphatidic acid phosphatase (PAP) Lppβ, was successfully reconstructed in an E. coli diacylglycerol kinase (dgkA) mutant strain. TAG production in this genetic background was optimized by increasing the levels of the TAG precursors, diacylglycerol and long-chain acyl-CoAs. For this we carried out a series of stepwise optimizations of the chassis by 1) fine-tuning the expression of the heterologous SCO0958 and lppβ genes, 2) overexpression of the S. coelicolor acetyl-CoA carboxylase complex, and 3) mutation of fadE, the gene encoding for the acyl-CoA dehydrogenase that catalyzes the first step of the β-oxidation cycle in E. coli. The best producing strain, MPS13/pET28-0958 ACC/pBAD-LPPβ rendered a cellular content of 4.85% cell dry weight (CDW) TAG in batch cultivation. Process optimization of fed-batch fermentation in a 1-L stirred-tank bioreactor resulted in cultures with an OD600nm of 80 and a product titer of 722.1 mg TAG L-1 at the end of the process. Conclusions: This study represents the highest reported fed-batch productivity of TAG reached by a model non-oleaginous bacterium. The organism used as a platform was an E. coli BL21 derivative strain containing a deletion in the dgkA gene and containing the TAG biosynthesis genes from S. coelicolor. The genetic studies carried out with this strain indicate that diacylglycerol (DAG) availability appears to be one of the main limiting factors to achieve higher yields of the storage compound. Therefore, in order to develop a competitive process for neutral lipid production in E. coli, it is still necessary to better understand the native regulation of the carbon flow metabolism of this organism, and in particular, to improve the levels of DAG biosynthesis.Ítem Acceso Abierto Solvent-free microwave-assisted synthesis of novel pyrazolo[40 ,30 :5,6]pyrido[2,3-d]pyrimidines with potential antifungal activity(Elsevier, 2015-03-17) Acosta, Paola; Insuasty, Braulio; Ortiz, Alejandro; Abonia, Rodrigo; Sortino, Maximiliano Andrés ; Zacchino, Susana; Quiroga, JairoÍtem Acceso Abierto Microwave-assisted synthesis of novel pyrazolo[3,4-g][1,8]naphthyridin-5-amine with potential antifungal and antitumor activity(MDPI, 2015-05-12) Acosta, Paola; Butassi, Estefanía; Insuasty, Braulio; Ortiz, Alejandro; Abonia, Rodrigo; Zacchino, Susana; Quiroga, JairoÍtem Acceso Abierto Synthesis, antiproliferative and antifungal activities of 1,2,3-triazole-substituted carnosic acid and carnosol derivatives(MDPI, 2015-05-14) Pertino, Mariano Walter; Theoduloz, Cristina; Butassi, Estefanía; Zacchino, Susana; Schmeda-Hirschmann, GuillermoÍtem Acceso Abierto Synthesis of new chiral 1,3-aminoalcohols derived from levoglucosenone and their application in asymmetric alkylations(Elsevier, 2015-06-10) Zanardi, María Marta; Suárez, Alejandra GracielaÍtem Acceso Abierto Antifungal activity of pyranonaphthoquinones obtained from Cipura paludosa bulbs(SAGE, 2015-09-01) Campos, Adriana; Rodrigues Souza, Greice Maria; Delle Monache, Franco; Butassi, Estefanía; Zacchino, Susana; Cechinel Filho, ValdirÍtem Acceso Abierto A coiled coil switch mediates cold sensing by the thermosensory protein DesK(Wiley, 2015-10-08) Saita, Emilio Adolfo; Abriata, Luciano Andrés; Tsai, Yi-Ting; Trajtenberg, Felipe; Lemmin, Thomas; Buschiazzo, Alejandro; Dal Peraro, Matteo; De Mendoza, Diego; Albanesi, DanielaThe thermosensor histidine kinase DesK from Bacillus subtilis senses changes in membrane fluidity initiating an adaptive response. Structural changes in DesK have been implicated in transmembrane signaling, but direct evidence is still lacking. On the basis of structure-guided mutagenesis, we now propose a mechanism of DesK-mediated signal sensing and transduction. The data indicate that stabilization/destabilization of a 2-helix coiled coil, which connects the transmembrane sensory domain of DesK to its cytosolic catalytic region, is crucial to control its signaling state. Computational modeling and simulations reveal couplings between protein, water and membrane mechanics. We propose that membrane thickening is the main driving force for signal sensing and that it acts by inducing helix stretching and rotation prompting an asymmetric kinase-competent state. Overall, the known structural changes of the sensor kinase, as well as further dynamic rearrangements that we now predict, consistently link structure determinants to activity modulation.Ítem Acceso Abierto Astringency reduction in red wine by whey proteins(Elsevier, 2015-12-11) Jauregi, Paula; Olatujoye, Jumoke B.; Cabezudo, Ignacio; Frazier, Richard A.; Gordon, Michael H.Ítem Acceso Abierto Antioxidant dietary fibre recovery from Brazilian Pinot noir grape pomace(Elsevier, 2016-01-11) Beres, Carolina; Simas-Tosin, Fernanda F.; Cabezudo, Ignacio; Freitas, Suely P.; Iacomini, Marcello; Mellinger-Silva, Caroline; Cabral, Lourdes M. C.Ítem Acceso Abierto A convenient approach to an advanced intermediate toward the naturally occurring, bioactive 6-substituted 5-hydroxy-4-aryl-1H-quinolin-2-ones(Royal Society of Chemistry, 2016-01-26) Simonetti, Sebastián Osvaldo; Larghi, Enrique Leandro; Kaufman, Teodoro SaúlÍtem Acceso Abierto Development of polymer-supported chiral aminoalcohols derived from biomass and their application to asymmetric alkylation(Elsevier, 2016-04) Botta, María Celeste; Biava, Hernán D.; Spanevello, Rolando Ángel; Mata, Ernesto Gabino; Suárez, Alejandra GracielaÍtem Acceso Abierto Identification of novel chemical scaffolds Inhibiting trypanothione synthetase from pathogenic trypanosomatids(Public Library of Science (PLOS), 2016-04-12) Benítez, Diego; Medeiros, Andrea; Fiestas, Lucía; Panozzo Zénere, Esteban Andrés; Maiwald, Franziska; Prousis, Kyriakos C.; Roussaki, Marina; Calogeropoulou, Theodora; Detsi, Anastasia; Jaeger, Timo; Šarlauskas, Jonas; Peterlin Mašič, Lucíja; Kunick, Conrad; Labadie, Guillermo Roberto; Flohé, Leopold; Comini, Marcelo A.