RESUMEN
Heat shock proteins are molecular chaperones linked to a myriad of physiological functions in both prokaryotes and eukaryotes. In this study, we show that the Aspergillus nidulans hsp30 (ANID_03555.1), hsp70 (ANID_05129.1), and hsp90 (ANID_08269.1) genes are preferentially expressed in an acidic milieu, whose expression is dependent on the palA (+) background under optimal temperature for fungal growth. Heat shock induction of these three hsp genes showed different patterns in response to extracellular pH changes in the palA(+) background. However, their accumulation upon heating for 2 h was almost unaffected by ambient pH changes in the palA (-) background. The PalA protein is a member of a conserved signaling cascade that is involved in the pH-mediated regulation of gene expression. Moreover, we identified several genes whose expression at pH 5.0 is also dependent on the palA (+) background. These results reveal novel aspects of the heat- and pH-sensing networks of A. nidulans.
Asunto(s)
Aspergillus nidulans/genética , Aspergillus nidulans/metabolismo , Proteínas Fúngicas/genética , Regulación Fúngica de la Expresión Génica , Proteínas del Choque Térmico HSP30/genética , Proteínas HSP70 de Choque Térmico/genética , Proteínas HSP90 de Choque Térmico/genética , Proteínas Fúngicas/metabolismo , Proteínas del Choque Térmico HSP30/metabolismo , Proteínas HSP70 de Choque Térmico/metabolismo , Proteínas HSP90 de Choque Térmico/metabolismo , Concentración de Iones de Hidrógeno , Datos de Secuencia Molecular , Transcripción GenéticaRESUMEN
The results of this study describe the identification and characterization of the Toxoplasma gondii alpha-crystallin/small heat shock protein (sHsp) family. By database (www.toxodb.org) search, five parasite sHsps (Hsp20, Hsp21, Hsp28, Hsp29, and the previously characterized Hsp30/Bag1) were identified. As expected, they share the homologous alpha-crystallin domain, which is the key characteristic of sHsps. However, the N-terminal segment of each protein contains unique characteristics in size and sequence. Most T. gondii sHsps are constitutively expressed in tachyzoites and fully differentiated bradyzoites, with the exception of Hsp30/Bag1. Interestingly, by subcellular localization we observed that T. gondii sHsps are located in different compartments. Hsp20 is located at the apical end of the cell, Hsp28 is located inside the mitochondrion, Hsp29 showed a membrane-associated labeling, and Hsp21 appeared throughout the cytosol of the parasites. These particular differences in the immunostaining patterns suggest that their targets and functions might be different.
Asunto(s)
Compartimento Celular , Proteínas del Choque Térmico HSP20/metabolismo , Proteínas del Choque Térmico HSP30/metabolismo , Proteínas Protozoarias/química , Proteínas Protozoarias/metabolismo , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Anticuerpos Antiprotozoarios/biosíntesis , Línea Celular , Citosol/metabolismo , ADN Protozoario , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Etiquetas de Secuencia Expresada , Técnica del Anticuerpo Fluorescente Indirecta , Expresión Génica , Genes Protozoarios , Proteínas del Choque Térmico HSP20/química , Proteínas del Choque Térmico HSP20/genética , Proteínas del Choque Térmico HSP20/inmunología , Proteínas del Choque Térmico HSP20/aislamiento & purificación , Proteínas del Choque Térmico HSP30/química , Proteínas del Choque Térmico HSP30/genética , Proteínas del Choque Térmico HSP30/inmunología , Proteínas del Choque Térmico HSP30/aislamiento & purificación , Humanos , Inmunohistoquímica , Estadios del Ciclo de Vida , Ratones , Ratones Endogámicos , Datos de Secuencia Molecular , Proteínas Protozoarias/genética , Proteínas Protozoarias/inmunología , Proteínas Protozoarias/aislamiento & purificación , Proteínas Recombinantes/química , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Toxoplasma/citología , Toxoplasma/genética , Toxoplasma/metabolismo , Toxoplasmosis/parasitología , Factores de Transcripción/química , Factores de Transcripción/genética , alfa-Cristalinas/química , alfa-Cristalinas/genética , alfa-Cristalinas/metabolismoRESUMEN
The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30-kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.