Microbiological Synthesis of Carotenoids: Pathways and Regulation

Carotenoids are naturally produced by plants, algae, and some bacteria and fungi, fulfilling functions as accessory photosynthetic pigments and antioxidants. Among carotenoids, the xanthophyll astaxanthin stands out for its antioxidant and nutraceutical properties, which are beneficial to human health, and also for its use in the aquaculture industry as nutritional supplement of salmonid fish. Many studies have focused on the search of natural sources of astaxanthin as an alternative production that guarantees the beneficial properties of this compound. In nature, few astaxanthin-producing organisms are known, being the microalgae Haematococcus pluvialis and the yeast Xanthophyllomyces dendrorhous the most promising microbiological systems for the biotechnological production of this carotenoid. In this chapter, we describe the carotenogenic pathways in these microorganisms and the proposed carotenogenesis regulation mechanisms. As an example, the influence of the carbon source, the regulation by catabolic repression and by sterols in the carotenogenesis in the yeast X. dendrorhous is described

Characterization of virus-like particles and identification of capsid proteins in Xanthophyllomyces dendrorhous

© 2015, Springer Science+Business Media New York. Two dsRNAs of estimated lengths of 5 (L1) and 3.7 (L2) kpb are commonly found in strains of the basidiomycetous yeast Xanthophyllomyces dendrorhous, and the presence of virus-like particles (VLPs) have been described in some strains. Recently, two putative totiviruses (XdV-L1A and XdV-L1B) were identified from L1 dsRNA and one (XdV-L2) from L2 dsRNA in the strain UCD 67-385. In some strains, there are smaller dsRNAs (0.9–1.4 kb) that probable are satellite elements. In this work, the VLPs from several strains of X. dendrorhous, which differ in their dsRNAs content, were separated by sucrose gradient and characterized in relation to the dsRNAs and proteins that compose them. It was found that all types of dsRNAs were encapsidated into VLPs, supporting the hypothesis that the smaller dsRNAs are satellite molecules. A main protein of approx. 76 or 37 kDa composed the virions that only have the L1-dsRNA or L2-dsRNA, respectively. In the strain UCD 67-385, these both proteins were identified as viral capsid protein (CP), allow to confirm the gag predicted ORFs in XdV-L1A, XdV-L1B, and XdV-L2, with CPs of 76.6, 76.2, and 38.8 kDa, respectively. Analysis of predicted structures of CPs of XdV-L1A and XdV-L1B, showed high similitudes with the CPs of ScV-L-A and other totiviruses.This work was supported by a Grant from Fondecyt (11060157), and a CONICYT Scholarships to Oriana Flores.Peer Reviewe

Alpha Clustering with a Hollow Structure --- Geometrical Structure of Alpha Clusters from Platonic Solids to Fullerene Shape

We study $\alpha$-cluster structure based on the geometric configurations with a microscopic framework, which takes full account of the Pauli principle, and which also employs an effective inter-nucleon force including finite-range three-body terms suitable for microscopic alpha-cluster models. Here, special attention is focused upon the $\alpha$ clustering with a hollow structure; all the $\alpha$ clusters are put on the surface of a sphere. All the Platonic solids (five regular polyhedra) and the fullerene-shaped polyhedron coming from icosahedral structure are considered. Furthermore, two configurations with dual polyhedra, hexahedron-octahedron and dodecahedron-icosahedron, are also scrutinized. As a consequence, we insist on the possible existence of stable $\alpha$-clustering with a hollow structure for all the configurations. Especially, two configurations, that is, dual polyhedra of dodecahedron-icosahedron and fullerene, have a prominent hollow structure compared with other six configurations

Proteomic analysis of the carotenogenic yeast Xanthophyllomyces dendrorhous

Martinez-Moya P, Watt SA, Niehaus K, Alcaino J, Baeza M, Cifuentes V. Proteomic analysis of the carotenogenic yeast Xanthophyllomyces dendrorhous. BMC Microbiology. 2011;11(1): 131.Background: The yeast Xanthophyllomyces dendrorhous is used for the microbiological production of the antioxidant carotenoid astaxanthin. In this study, we established an optimal protocol for protein extraction and performed the first proteomic analysis of the strain ATCC 24230. Protein profiles before and during the induction of carotenogenesis were determined by two-dimensional polyacrylamide gel electrophoresis and proteins were identified by mass spectrometry. Results: Among the approximately 600 observed protein spots, 131 non-redundant proteins were identified. Proteomic analyses allowed us to identify 50 differentially expressed proteins that fall into several classes with distinct expression patterns. These analyses demonstrated that enzymes related to acetyl-CoA synthesis were more abundant prior to carotenogenesis. Later, redox-and stress-related proteins were up-regulated during the induction of carotenogenesis. For the carotenoid biosynthetic enzymes mevalonate kinase and phytoene/squalene synthase, we observed higher abundance during induction and/or accumulation of carotenoids. In addition, classical antioxidant enzymes, such as catalase, glutathione peroxidase and the cytosolic superoxide dismutases, were not identified. Conclusions: Our results provide an overview of potentially important carotenogenesis-related proteins, among which are proteins involved in carbohydrate and lipid biosynthetic pathways as well as several redox-and stress-related proteins. In addition, these results might indicate that X. dendrorhous accumulates astaxanthin under aerobic conditions to scavenge the reactive oxygen species (ROS) generated during metabolism

Regulation of carotenogenesis in the red yeast Xanthophyllomyces dendrorhous: the role of the transcriptional co-repressor complex Cyc8–Tup1 involved in catabolic repression

Background: The yeast Xanthophyllomyces dendrorhous produces carotenoids of commercial interest, including astaxanthin and β-carotene. Although carotenogenesis in this yeast and the expression profiles of the genes controlling this pathway are known, the mechanisms regulating this process remain poorly understood. Several studies have demonstrated that glucose represses carotenogenesis in X. dendrorhous, suggesting that this pathway could be regulated by catabolic repression. Catabolic repression is a highly conserved regulatory mechanism in eukaryotes and has been widely studied in Saccharomyces cerevisiae. Glucose-dependent repression is mainly observed at the transcriptional level and depends on the DNA-binding regulator Mig1, which recruits the co-repressor complex Cyc8-Tup1, which then represses the expression of target genes. In this work, we studied the regulation of carotenogenesis by catabolic repression in X. dendrorhous, focusing on the role of the co-repressor complex Cyc8-Tup1. Results: The X. dendrorhous CYC8 and TUP1 genes were identified, and their functions were demonstrated by heterologous complementation in S. cerevisiae. In addition, cyc8 and tup1 mutant strains of X. dendrorhous were obtained, and both mutations were shown to prevent the glucose-dependent repression of carotenogenesis in X. dendrorhous, increasing the carotenoid production in both mutant strains. Furthermore, the effects of glucose on the transcript levels of genes involved in carotenogenesis differed between the mutant strains and wild-type X. dendrorhous, particularly for genes involved in the synthesis of carotenoid precursors, such as HMGR, idi and FPS. Additionally, transcriptomic analyses showed that cyc8 and tup1 mutations affected the expression of over 250 genes in X. dendrorhous. Conclusions: The CYC8 and TUP1 genes are functional in X. dendrorhous, and their gene products are involved in catabolic repression and carotenogenesis regulation. This study presents the first report involving the participation of Cyc8 and Tup1 in carotenogenesis regulation in yeast.FONDECYT 1140504 and by a graduate scholarships CONICYT 21110252 to PC and MECESUP 2-UCH0604 to NBPeer Reviewe

Aislamiento de secuencias de replicación autónoma de Xanthophyllomyces dendrorhous en Saccharomyces cereviciae

Xanthophyllomyces dendrorhous (=Phaffia rhodozyma ), es una levadura basidiomicética carotenogénica, en la cual aspectos importantes de su biologia, como la organización general su genoma, número de cromosomas y nivel de ploidía, aún no son completamente entendidos. En atención a esto, se han orientado esfuerzos hacia la obtención de marcadores genéticos de auxotrofia, pigmentación y resistencia a antibióticos. Además. se ha progresado lentamente en estudios moleculares con el objetivo de aumentar el conocimiento de su genética,mediante el desarrollo de procedimientos de transformación genética, los cuales tienen una eficiencia baja.Con el objeto de construir un vector de clonado de X. dendrorhous, se describen los experimentos para lograr el clonamiento de Secuencias de Replicación Autónoma (ARS) de este basidiomicete en la levaduraSaccharomyces cerevisiae. Para ello se procedió a transformar la cepa FBL1 -8B de S. cerevisiae con clones recombinantes de la genoteca de X. dendrorhous construida en el vector de integración YIp5. Como resultado se lograron 4 transformantes URA3+ de S.cerevisiae, denominados 6(1), 37(1), 38(1) Y 38(4). Adicionalmente se realizaron experimentos de rescate de plásmidos mediante transformación de E. coli DH5a con DNA total de los transformantes de levadura, rescatándose 6 clones recombinantes. El análisis de restricción de los plásmidos, indicó que 5 son idénticos, estando formados por el vector YIp5 (5.4 kb) Y 3 fragmentos BamHI de 7.7, 2.4 Y J.5 kb. El otro carece del inserto de 2.4 kb. La retransformación de S. cerevciae con estos plásmidos se presentó en alta frecuencia y sugiere la presencia de un ARS. El subclonado de los insertos indica que la función ARS radica en el mayor y corresponde a un rearreglo del vector e inserto

Sterol Regulatory Element-Binding Protein (Sre1) Promotes the Synthesis of Carotenoids and Sterols in Xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous is a basidiomycete yeast that synthesizes carotenoids, mainly astaxanthin, which are of great commercial interest. Currently, there are many unknown aspects related to regulatory mechanisms on the synthesis of carotenoids in this yeast. Our recent studies showed that changes in sterol levels and composition resulted in upregulation of genes in the mevalonate pathway required for the synthesis of carotenoid precursors, leading to increased production of these pigments. Sterol Regulatory Element-Binding Proteins (SREBP), called Sre1 in yeast, are conserved transcriptional regulators of sterol homeostasis and other cellular processes. Given the results linking sterols and carotenoids, we investigated the role of SREBP in sterol and carotenoid synthesis in X.dendrorhous. In this study, we present the identification and functional characterization of the X.dendrorhousSRE1 gene, which encodes the transcription factor Sre1. The deduced protein has the characteristic features of SREBP/Sre1 and binds to consensus DNA sequences in vitro. RNA-seq analysis and chromatin-immunoprecipitation experiments showed that genes of the mevalonate pathway and ergosterol biosynthesis are directly regulated by Sre1. The sre1- mutation reduced sterol and carotenoid production in X. dendrorhous, and expression of the Sre1 N-terminal domain (Sre1N) increased carotenoid production more than twofold compared to wild-type. Overall, our results indicate that in X. dendrorhous transcriptional regulation of genes in the mevalonate pathway control production of the isoprenoid derivatives, carotenoids and sterol. Our results provide new insights into the conserved regulatory functions of SREBP/Sre1 and identify pointing to the SREBP pathway as a potential target to enhance carotenoid production in X. dendrorhous

Sterol regulatory element-binding protein (Sre1) promotes the synthesis of carotenoids and sterols in xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous is a basidiomycete yeast that synthesizes carotenoids, mainly astaxanthin, which are of great commercial interest. Currently, there are many unknown aspects related to regulatory mechanisms on the synthesis of carotenoids in this yeast. Our recent studies showed that changes in sterol levels and composition resulted in upregulation of genes in the mevalonate pathway required for the synthesis of carotenoid precursors, leading to increased production of these pigments. Sterol Regulatory Element-Binding Proteins (SREBP), called Sre1 in yeast, are conserved transcriptional regulators of sterol homeostasis and other cellular processes. Given the results linking sterols and carotenoids, we investigated the role of SREBP in sterol and carotenoid synthesis in X. dendrorhous. In this study, we present the identification and functional characterization of the X. dendrorhous SRE1 gene, which encodes the transcription factor Sre1. The deduced protein has the characteristic features of SREBP/Sre1 and binds to consensus DNA sequences in vitro. RNA-seq analysis and chromatin-immunoprecipitation experiments showed that genes of the mevalonate pathway and ergosterol biosynthesis are directly regulated by Sre1. The sre1- mutation reduced sterol and carotenoid production in X. dendrorhous, and expression of the Sre1 N-terminal domain (Sre1N) increased carotenoid production more than twofold compared to wild-type. Overall, our results indicate that in X. dendrorhous transcriptional regulation of genes in the mevalonate pathway control production of the isoprenoid derivatives, carotenoids and sterol. Our results provide new insights into the conserved regulatory functions of SREBP/Sre1 and identify pointing to the SREBP pathway as a potential target to enhance carotenoid production in X. dendrorhous. domain (Sre1N) increased carotenoid production more than twofold compared to wild-type. Overall, our results indicate that in X. dendrorhous transcriptional regulation of genes in the mevalonate pathway control production of the isoprenoid derivatives, carotenoids and sterol. Our results provide new insights into the conserved regulatory functions of SREBP/Sre1 and identify pointing to the SREBP pathway as a potential target to enhance carotenoid production in X. dendrorhous.FONDECYT 1160202 and by graduate scholarships CONICYT 21130708 to MSG and CONICYT 2117061

Guía de transición para la LOPD: los nuevos derechos

[ES] La necesidad de adaptación de España al Reglamento General de Protección de Datos causó el desarrollo de una nueva ley de protección de datos, llamada Ley Orgánica de Protección de Datos y Garantía de los Derechos Digitales, que se adecuase al reglamento europeo y que garantizase la protección de las personas físicas, en lo que respecta al tratamiento de sus datos personales. Este trabajo proporciona todos los datos necesarios para ser capaz de cumplir la normativa de protección de datos tras los cambios provocados por la entrada en vigor de la Ley Orgánica 3/2018, de 5 de diciembre, de Protección de Datos Personales y Garantía de los Derechos Digitales. Adicionalmente se describe el proceso llevado a cabo para la creación de una lista de tareas pendientes mediante el software de hojas de cálculo llamado “Microsoft Excel”, que pueda ser de utilidad para los encargados de protección de datos.[EN] The need to adapt Spain to the General Data Protection Regulation caused the development of a new data-protection law, called Organic Law on the Protection of Personal Data and the Guarantee of Digital Rights, that fits to the European regulation and guarantees the protection of physical persons, with regard to the processing of their personal data. This work provides all necesary information to be able to follow the data-protection rules after the changes caused by the entry into force of the Spanish Organic Law 3/2018, of 5 december, on the Protection of Personal Data and the Guarantee of Digital Rights. Additionally, it describes the process carried out to create a to-do list using the spreadsheet software called “Microsoft Excel”, which may be useful to processors.Giménez Hervás, C. (2019). Guía de transición para la LOPD: los nuevos derechos. http://hdl.handle.net/10251/128599TFG