Julián Rodríguez Talou

Exploring different strategies to express Dengue virus envelope protein in a plant system.

Dengue virus envelope glycoprotein (E-protein) is the main protein associated with immunity induction. To produce a candidate for subunit vaccines and to provide an antigen for diagnostic kits, it was expressed in a novel plant system using deconstructed viral modules. A truncated version of the E-protein was designed to be expressed alone and co-expressed with Dengue virus structural proteins. As well, the critical domain III of E-protein was fused to hepatitis B core antigen (HBcore). The recombinant proteins were produced in Nicotiana benthamiana plants and were reactive with the anti-E antibody. The fusion was reactive with both anti-E and anti-HBcore antibodies.

Expression of Brugmansia candida Hyoscyamine 6beta-Hydroxylase gene in Saccharomyces cerevisiae and its potential use as biocatalyst

BackgroundTropane alkaloids, mainly hyoscyamine and scopolamine, are widely used in medicine due to their anticholinergic activity. Scopolamine has a higher demand being the more valuable alkaloid due to its fewer side effects and higher physiological activity. Anisodamine (6β-hydroxyhyoscyamine) is the intermediate in the conversion of hyoscyamine into scopolamine. Current studies report that this alkaloid is potentially applicable in medicine. The gene that codifies for Hyoscyamine 6-β hydroxylase, the enzyme responsible for hyoscyamine hydroxylation and epoxidation, leading to scopolamine was isolated from Brugmansia candida.ResultsThe h6h cDNA was cloned into pYES2.1 and pYES2.1/V5-His-TOPO vectors to produce an untagged and a tagged protein, respectively. The H6H enzyme was produced in Saccharomyces cerevisiae in order to obtain a biological catalyst for potential industrial applications. Protein extracts of the induced yeast were analyzed by Western blot. The expression was detected 4 h after induction and no degradation was observed during the period assayed. The tagged and the untagged proteins were able to transform hyoscyamine, showing a functional expression of the h6h cDNA.ConclusionThe strains obtained in this work are promising and potentially applicable in biocatalytic processes.

Role of reactive oxygen species and proline cycle in anthraquinone accumulation in Rubia tinctorum cell suspension cultures subjected to methyl jasmonate elicitation

Elicitors are compounds or factors capable of triggering a defense response in plants. This kind of response involves signal transduction pathways, second messengers and events such as Reactive Oxygen Species (ROS) generation, proline accumulation and secondary metabolite production. Anthraquinone (AQs) biosynthesis in Rubia tinctorum L. involves different metabolic routes, including shikimate and 2-C-methyl-d-erythritol-4-phosphate (MEP) pathways. It has been proposed that the proline cycle could be coupled with the pentose phosphate pathway (PPP), since the NADP+ generated by this cycle could act as a cofactor of the first enzymes of the PPP. The end-product of this pathway is erithrose-4-phosphate, which becomes the substrate of the shikimate pathway. The aim of this work was to study the effect of methyl jasmonate (MeJ), a well-known endogenous elicitor, on the PPP, the proline cycle and AQs production in R. tinctorum cell suspension cultures, and to elucidate the role of ROS in MeJ elicitation. Treatment with MeJ resulted in AQs as well as proline accumulation, which was mimicked by the treatment with a H₂O₂-generating system. Both MeJ-induced effects were abolished in the presence of diphenyliodonium (DPI), a NADPH oxidase inhibitor (main source of ROS). Treatment with the elicitor failed to induce PPP; therefore, this route did not turn out to be limiting the carbon flux to the shikimate pathway.

Anisodamine Production from Natural Sources: Seedlings and Hairy Root Cultures of Argentinean and Colombian Brugmansia candida Plants

The tropane alkaloid anisodamine ( 2) is obtained by 6 beta-hydroxylation of hyoscyamine ( 1). The application of this alkaloid in medicine is gaining attention due to the wide range of therapeutic applications described in addition to its anticholinergic activity. In this work, the production of anisodamine ( 2) by IN VITRO cultures of BRUGMANSIA CANDIDA (Argentinean and Colombian samples) was studied. This alkaloid was estimated in different organs of IN VITRO-germinated seedlings as well as in hairy roots obtained from seedlings from both sources. Colombian roots exhibited the highest content of tropane alkaloids, with anisodamine ( 2) being the main alkaloid measured. In the leaves, the main alkaloid was scopolamine ( 3) and no significant differences were observed between Argentinean and Colombian leaves. The tropane alkaloid content in Argentinean hairy roots was significantly higher than in Colombian ones. Also, in the Argentinean samples the main alkaloid detected was anisodamine ( 2). Argentinean and Colombian B. CANDIDA seedlings and hairy roots appear to be a promising system for the production of anisodamine ( 2).

Increasing anthraquinone production by overexpression of 1-deoxy-D-xylulose-5-phosphate synthase in transgenic cell suspension cultures of Morinda citrifolia

A Morinda citrifolia cell line was obtained by overexpresion of 1-deoxy-d-xylulose 5-phosphate synthase (DXS) from Catharanthus roseus, a key enzyme of the metabolic pathway of anthraquinones (AQs). This cell line increased AQs production by about 24% compared to the control cell line. This transgenic cell line which carries dxs cDNA isolated from Catharanthus roseus, was achieved by direct transformation of cell suspension cultures of M. citrifolia using a hypervirulent Agrobacterium tumefaciens strain. The effects of the overexpression of the dxs gene also resulted in increased levels of dxs mRNA transcripts and DXS activity compared to the control cell line. In addition, total phenolics and phenylalanine ammonia-lyase activity were evaluated and were significantly higher in the transgenic line than in controls.

In situ removal of consensus dengue virus envelope protein domain III fused to hydrophobin in Pichia pastoris cultures

This work describes a novel strategy for the integrated expression and purification of recombinant proteins in Pichia pastoris cultures. Hydrophobins can be used as fusion tags, proteins fused to them alter their hydrophobicity and can be purified by aqueous two-phase systems (ATPS) based on non-ionic surfactants. Here, the consensus dengue virus envelope protein domain III fused to hydrophobin I of Trichoderma reesei was expressed in Pichia pastoris cultures and an in situ product removal by an ATPS using a non-ionic detergent, (Triton X-114) was performed. The protein was produced and purified directly from the yeast culture supernatant both efficiently and with no loss. The purified protein was properly immobilized by adsorption in solid phase and recognized by anti-dengue antibodies, showing its potential for the development of an indirect immunoassay for dengue virus.

Biosynthesis of Sesquiterpene Lactones in Plants and Metabolic Engineering for Their Biotechnological Production

In the present chapter, we review some aspects of the biosynthesis of sesquiterpene lactones and its regulation in different medicinal and aromatic plants used in the pharmaceutical industry. In this sense, we describe the mevalonate and the 2-C-methyl-D-erythritol 4-phosphate pathways, which generate the corresponding isoprenoid precursors (isopentenyl diphosphate and dimethylallyl diphosphate), as well as the late pathways that lead to sesquiterpene lactone biosynthesis. This chapter also analyses the role of the transcription factors involved in the regulation of sesquiterpene lactone biosynthesis and the different biotechnological approaches that have been developed for sesquiterpene lactone production. In vitro plant cell cultures (comprising micropropagation and plant cell suspension, shoot and root cultures) have emerged as a production platform for many plant secondary metabolites, since they allow their production under controlled conditions and shorter production cycles. The characterisation and isolation of genes involved in the regulation of sesquiterpene lactone biosynthetic pathways have allowed the design of metabolic engineering strategies to increase the production of these metabolites. Moreover, we discuss different strategies to increase sesquiterpene lactone production through genetic engineering. We also focus on the metabolic engineering of the artemisinin biosynthetic pathway in Artemisia annua. This metabolic pathway has become a model system not only for the biotechnological production of sesquiterpene lactones but also for the improvement of other plant secondary metabolic pathways. Finally, we analyse the successful expression of the complete artemisinin biosynthetic pathway in Escherichia coli and Saccharomyces cerevisiae, which has led to the efficient accumulation of artemisinic acid in these microorganisms.