Romina Chaves - Academia.edu (original) (raw)

Papers by Romina Chaves

Research paper thumbnail of Democracia y control jurisdiccional de constitucionalidad

Un diseño institucional generalizado en las democracias constitucionales consiste en consagrar un... more Un diseño institucional generalizado en las democracias constitucionales consiste en consagrar una carta de derechos fundamentales garantizando su supremacía a través del control judicial de constitucionalidad. Contra él, no obstante, el llamado "argumento contramayoritario" ha denunciado que su implementación implica dejar en manos de unas pocas personas inamovibles en sus cargos y con escasa representatividad la última palabra sobre cuestiones de máxima importancia: el alcance y contenido de los derechos fundamentales. En el marco del presente trabajo se intentará demostrar que la objeción contramayoritaria al control judicial de constitucionalidad se apoya en presupuestos cuestionables respecto de la interpretación. Asimismo se tratará de analizar si está justificado un activismo judicial dentro del ideal de democracia constitucional como medio de evitar la exposición de bienes fundamentales a la regla de la mayoría.

Research paper thumbnail of La proteína med8 conecta la máquina general de la transcripción con sistemas de regulación de la expresión génica

Con el fin de identificar y caracterizar nuevos factores transcripcionales implicados en el mecan... more Con el fin de identificar y caracterizar nuevos factores transcripcionales implicados en el mecanismo de regulacion por glucosa en Sacchromyces cerevisiae se han llevado a cabo en la primera parte del trabajo dos estrategias de experimentacion independientes: A)Obtencion de mutantes afectados enla represion a nivel del elemento DRS2 el gen HXK2. B)Identificacion de proteinas que se unen directamente a la secuencia UAS del prmotor SUC2. La primera condujo a la seleccion y caracterizacion parcial de dos mutantes afectados en la regulacion a traves del elemento DRS2 del gen HXK2, asi como la identificacion del producto del gen TIM9 como un posible factor implicado en la regulacion de la expresion de los genes SUC2 y HXK2. La segunda dio lugar a la identificacion del producto del gen MED8 como un nuevo factor transcripcional involucrado en el sistema de represion por glucosa en S.cerevisiae. La proteina Med8 es una subunidad esencial del subcompleto Srb/mediador del holoenzima de la ARN...

Research paper thumbnail of Mediator Factor Med8p Interacts with the Hexokinase 2: Implication in the Glucose Signalling Pathway of Saccharomyces cerevisiae

Journal of Molecular Biology, 2002

In the presence of glucose the protein hexokinase 2 (Hxk2p), normally resident in the cytosol, is... more In the presence of glucose the protein hexokinase 2 (Hxk2p), normally resident in the cytosol, is translocated to the nucleus where it impairs the activation of transcription of the glucose-repressed genes HXK1, GLK1 and SUC2, and promotes the activation of transcription of the glucoseinduced genes HXK2 and HXT1. Here, we demonstrate the involvement of an heptameric motif, named the MED8 site, in the direct binding of the mediator protein Med8p, either as a monomer or as a homodimer. Because this site was previously involved in the Hxk2p-dependent glucose-induced regulation of gene transcription, we tested whether Hxk2p interacts with Med8p. Our results show that Hxk2 and Med8 proteins are physically associated and that this Hxk2p-Med8p interaction is of physiological significance because both proteins have been found interacting together in a cluster with DNA fragments containing the MED8 site. We conclude that Hxk2p operates through the MED8 site, by interacting with Med8p, in the glucose signal transduction pathway of Saccharomyces cerevisiae.

Research paper thumbnail of Isocitrate lyase localisation in Saccharomyces cerevisiae cells

Gene, 1997

The isocitrate lyase from Saccharomyces cerevisiae was only located in the cell cytoplasm. This p... more The isocitrate lyase from Saccharomyces cerevisiae was only located in the cell cytoplasm. This protein was found not to be associated with cell organelles, even under growth conditions that induce peroxisome proliferation. This conclusion is supported by experiments carried out by damaging the protoplast plasma membrane with DEAE-dextran, by differential centrifugation of osmotically lysed protoplast and by using the green fluorescent protein (GFP) of Aequorea victoria as a reporter fusion tag to localise the subcellular compartment to which isocitrate lyase is targeted.

Research paper thumbnail of Med8, a Subunit of the Mediator CTD Complex of RNA Polymerase II, Directly Binds to Regulatory Elements ofSUC2andHXK2Genes

Biochemical and Biophysical Research Communications, 1999

In a search to identify new factors required for expression of SUC2 gene in Saccharomyces cerevis... more In a search to identify new factors required for expression of SUC2 gene in Saccharomyces cerevisiae, we have partially purified a 27 kDa protein (p27) that bound both the DRSs of the HXK2 gene and the UASs of SUC2 gene. The amino terminal sequence of p27 identified the MED8 gene (open reading frame YBR193C), located in chromosome II of S. cerevisiae, as the gene coding for the protein. Disruption of this gene has demonstrated that is an essential gene for yeast growth. To determine whether the p27 protein represents the Med8 product, we expressed MED8 gene in E. coli and demonstrated that the heterologous synthesized protein specifically binds to both UAS SUC2 and DRS2 HXK2. This observation suggests that Med8 may be important for the coupling of the glucose repression pathway of SUC2 gene to the HXK2 gene expression. Med8 has been described as a mediator protein interacting with the CTD of the RNA polymerase II. Thus, the role of Med8 could be to act as coupling factor by linking activating and repressing transcription complexes to the RNA polymerase II holoenzyme transcriptional machinery.

Research paper thumbnail of Democracia y control jurisdiccional de constitucionalidad

Un diseño institucional generalizado en las democracias constitucionales consiste en consagrar un... more Un diseño institucional generalizado en las democracias constitucionales consiste en consagrar una carta de derechos fundamentales garantizando su supremacía a través del control judicial de constitucionalidad. Contra él, no obstante, el llamado "argumento contramayoritario" ha denunciado que su implementación implica dejar en manos de unas pocas personas inamovibles en sus cargos y con escasa representatividad la última palabra sobre cuestiones de máxima importancia: el alcance y contenido de los derechos fundamentales. En el marco del presente trabajo se intentará demostrar que la objeción contramayoritaria al control judicial de constitucionalidad se apoya en presupuestos cuestionables respecto de la interpretación. Asimismo se tratará de analizar si está justificado un activismo judicial dentro del ideal de democracia constitucional como medio de evitar la exposición de bienes fundamentales a la regla de la mayoría.

Research paper thumbnail of La proteína med8 conecta la máquina general de la transcripción con sistemas de regulación de la expresión génica

Con el fin de identificar y caracterizar nuevos factores transcripcionales implicados en el mecan... more Con el fin de identificar y caracterizar nuevos factores transcripcionales implicados en el mecanismo de regulacion por glucosa en Sacchromyces cerevisiae se han llevado a cabo en la primera parte del trabajo dos estrategias de experimentacion independientes: A)Obtencion de mutantes afectados enla represion a nivel del elemento DRS2 el gen HXK2. B)Identificacion de proteinas que se unen directamente a la secuencia UAS del prmotor SUC2. La primera condujo a la seleccion y caracterizacion parcial de dos mutantes afectados en la regulacion a traves del elemento DRS2 del gen HXK2, asi como la identificacion del producto del gen TIM9 como un posible factor implicado en la regulacion de la expresion de los genes SUC2 y HXK2. La segunda dio lugar a la identificacion del producto del gen MED8 como un nuevo factor transcripcional involucrado en el sistema de represion por glucosa en S.cerevisiae. La proteina Med8 es una subunidad esencial del subcompleto Srb/mediador del holoenzima de la ARN...

Research paper thumbnail of Mediator Factor Med8p Interacts with the Hexokinase 2: Implication in the Glucose Signalling Pathway of Saccharomyces cerevisiae

Journal of Molecular Biology, 2002

In the presence of glucose the protein hexokinase 2 (Hxk2p), normally resident in the cytosol, is... more In the presence of glucose the protein hexokinase 2 (Hxk2p), normally resident in the cytosol, is translocated to the nucleus where it impairs the activation of transcription of the glucose-repressed genes HXK1, GLK1 and SUC2, and promotes the activation of transcription of the glucoseinduced genes HXK2 and HXT1. Here, we demonstrate the involvement of an heptameric motif, named the MED8 site, in the direct binding of the mediator protein Med8p, either as a monomer or as a homodimer. Because this site was previously involved in the Hxk2p-dependent glucose-induced regulation of gene transcription, we tested whether Hxk2p interacts with Med8p. Our results show that Hxk2 and Med8 proteins are physically associated and that this Hxk2p-Med8p interaction is of physiological significance because both proteins have been found interacting together in a cluster with DNA fragments containing the MED8 site. We conclude that Hxk2p operates through the MED8 site, by interacting with Med8p, in the glucose signal transduction pathway of Saccharomyces cerevisiae.

Research paper thumbnail of Isocitrate lyase localisation in Saccharomyces cerevisiae cells

Gene, 1997

The isocitrate lyase from Saccharomyces cerevisiae was only located in the cell cytoplasm. This p... more The isocitrate lyase from Saccharomyces cerevisiae was only located in the cell cytoplasm. This protein was found not to be associated with cell organelles, even under growth conditions that induce peroxisome proliferation. This conclusion is supported by experiments carried out by damaging the protoplast plasma membrane with DEAE-dextran, by differential centrifugation of osmotically lysed protoplast and by using the green fluorescent protein (GFP) of Aequorea victoria as a reporter fusion tag to localise the subcellular compartment to which isocitrate lyase is targeted.

Research paper thumbnail of Med8, a Subunit of the Mediator CTD Complex of RNA Polymerase II, Directly Binds to Regulatory Elements ofSUC2andHXK2Genes

Biochemical and Biophysical Research Communications, 1999

In a search to identify new factors required for expression of SUC2 gene in Saccharomyces cerevis... more In a search to identify new factors required for expression of SUC2 gene in Saccharomyces cerevisiae, we have partially purified a 27 kDa protein (p27) that bound both the DRSs of the HXK2 gene and the UASs of SUC2 gene. The amino terminal sequence of p27 identified the MED8 gene (open reading frame YBR193C), located in chromosome II of S. cerevisiae, as the gene coding for the protein. Disruption of this gene has demonstrated that is an essential gene for yeast growth. To determine whether the p27 protein represents the Med8 product, we expressed MED8 gene in E. coli and demonstrated that the heterologous synthesized protein specifically binds to both UAS SUC2 and DRS2 HXK2. This observation suggests that Med8 may be important for the coupling of the glucose repression pathway of SUC2 gene to the HXK2 gene expression. Med8 has been described as a mediator protein interacting with the CTD of the RNA polymerase II. Thus, the role of Med8 could be to act as coupling factor by linking activating and repressing transcription complexes to the RNA polymerase II holoenzyme transcriptional machinery.