RESUMO
The parasite Trichomonas vaginalis is the causative agent of trichomoniasis, a prevalent sexually transmitted infection. Here, we report the cellular analysis of T.vaginalis tetraspanin family (TvTSPs). This family of membrane proteins has been implicated in cell adhesion, migration and proliferation in vertebrates. We found that the expression of several members of the family is up-regulated upon contact with vaginal ectocervical cells. We demonstrate that most TvTSPs are localized on the surface and intracellular vesicles and that the C-terminal intracellular tails of surface TvTSPs are necessary for proper localization. Analyses of full-length TvTSP8 and a mutant that lacks the C-terminal tail indicates that surface-localized TvTSP8 is involved in parasite aggregation, suggesting a role for this protein in parasite : parasite interaction.
Assuntos
Tetraspaninas/análise , Trichomonas vaginalis/química , Agregação Celular , Vesículas Citoplasmáticas/química , Análise Mutacional de DNA , Células Epiteliais/parasitologia , Perfilação da Expressão Gênica , Proteínas de Membrana/análise , Transporte Proteico , Trichomonas vaginalis/genéticaRESUMO
Toxoplasma gondii is an obligate intracellular parasite and the causative agent of toxoplasmosis. Protein palmitoylation is known to play roles in signal transduction and in enhancing the hydrophobicity of proteins thus contributing to their membrane association. Global inhibition of protein palmitoylation has been shown to affect T. gondii physiology and invasion of the host cell. However, the proteins affected by this modification have been understudied. This paper shows that the small heat shock protein 20 from T. gondii (TgHSP20) is synthesized as a mature protein in the cytosol and is palmitoylated in three cysteine residues. However, its localization at the inner membrane complex (IMC) is dependent only on N-terminal palmitoylation. Absence or incomplete N-terminal palmitoylation causes TgHSP20 to partially accumulate in a membranous structure. Interestingly, TgHSP20 palmitoylation is not responsible for its interaction with the daughter cells IMCs. Together, our data describe the importance of palmitoylation in protein targeting to the IMC in T. gondii.
Assuntos
Fibroblastos/metabolismo , Proteínas de Choque Térmico HSP20/metabolismo , Membranas Intracelulares/metabolismo , Lipoilação , Toxoplasma/metabolismo , Toxoplasmose/parasitologia , Western Blotting , Células Cultivadas , Cisteína/química , Cisteína/genética , Cisteína/metabolismo , Citosol/metabolismo , Fibroblastos/citologia , Imunofluorescência , Proteínas de Choque Térmico HSP20/genética , Humanos , Imunoprecipitação , Mutação/genética , Transporte Proteico , Transdução de Sinais , Toxoplasma/crescimento & desenvolvimento , Toxoplasmose/metabolismoRESUMO
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.
