INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
gVps10p like receptor: a novel protein involved in sorting of soluble hydrolases in the protozoan parasite Giardia lamblia.
Autor/es:
MIRAS SL,; RIVERO, M R; FELIZIANI, C; ZAMPONI N,; QUIROGA R; ROPOLO A S; TOUZ MC.
Lugar:
Mar del Plata
Reunión:
Congreso; IX Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2011
Resumen:
Eukaryotic cells contain numerous distinct membrane bound organelles. To maintain the functional identities of these organelles, specific sets of proteins must be efficiently sorted and delivered to each intracellular compartment. The targeting of lysosomal enzymes from their site of synthesis in the rough endoplasmic reticulum (RER) to their final destination in lysosomes is directed by a series of protein and recognition signals. For example, in the well-characterized lysosomal protein delivery pathway in mammalian cells, soluble lysosomal hydrolases are modified in the Golgi by the attachment of a mannose 6-phosphate group on their N-linked oligosaccharide side chains. In the TGN this tag is recognized by a set of two mannose 6-phosphate receptors (MPRs) that mediate sorting of the hydrolases to the endosome where the hydrolases dissociate from the receptors due to the acidic environment. The delivery of proteins to the vacuolar compartment is mediated by the secretory pathway and is one of the best-characterized examples of an intracellular protein-sorting process in S. cerevisiae. However, Giardia does not contain a recognized Golgi apparatus or a typical endosome/lysosome system. The goal of this work, is to summarize our current understanding of the structure and function of the gVps10p like receptor in sorting of lysosomal enzymes to the peripheral vacuoles, through a specific pathway, in the protozoan parasite Giardia lamblia. By means of bioinformatic tools we determine that the receptor is a type I transmembrana protein with a WD40 motif in the luminal portion and trough proteinase K assay we could corroborate that prediction. IFA and confocal microscopy of stably transfected trophozoites over-expressing gVps10p-HA fusion protein, showed that the receptor localize around the nuclei colocalizing with the ER marker BIP (Immunoglobulin Binding Protein). Co-expression of gVps10p-HA and gAcPh-V5 fusion proteins showed colocalization around nuclei and in the lysosomal peripheral vacuoles. Besides, by yeast-two hybrid assays, we found that gVps10p not only binds to Acid phosphatase (gAcPh) if not also it binds different soluble hydrolases like cystein proteases of the Cathepsins B family, gCP1 and gCP3. On other hand, gVps10p-YQII-HA fusion protein, lacking the cytoplasmic tyrosine motif, showed a different subcelular distribution possibly related with changes in protein trafficking. These results constitute the first evidence about the occurrence of a gVps10p like receptor in the protozoan parasite Giardia lamblia.