INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Analysis of the nuclear translocation of arginine deiminase during Giardia differentiation.
Autor/es:
GONZALO MAYOL; NATACHA ZLOCOWSKI; VRANYCH CV; MARIA CAROLINA TOUZ; ROPOLO ANDREA
Reunión:
Congreso; X Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2014
Resumen:
SUMOylation, a posttranslational modification of
proteins, is vital in eukaryotic cells. In a previous work, we analyzed the
role of SUMO protein and the genes encoding the putative enzymes of the SUMOylation
pathway in the parasite Giardia lamblia.
Although we observed several SUMOylated proteins, only the enzyme Arginine
Deiminase (ADI) was confirmed as a SUMOylated substrate. During the
encystations process, ADI translocates to the nuclei. The first signal that drives
ADI to the nuclei is the SUMOylation of the enzyme which probably exposes nuclear
localization signals promoting the entry of the enzyme to the nuclei. Once inside
the nuclei, ADI acts as a peptidyl arginine deiminase and induces the
downregulation of cwp genes, allowing the encystation process to end. In this
work we found that in trophozoites overexpressing the SUMO protein, ADI is
highly observed inside the nuclei and also the production of cyst is lower than
in wild type trophozoites. Moreover, in immunofluorescence assays, ADI and SUMO
co-localize in the nuclear membrane. In other eukaryotic cells, proteins with
nuclear localization signals are transported across the nuclear envelope by a
family of transport proteins called karyopherins or importins. In the Giardia
genome data base, only the importin â-3 subunit (GL50803_15106) is described. It shows the
HEAT domain involved in intracellular transport and contains a domain with high
probability of SUMO interaction. The entire open reading frame of the importin
gene was amplified, cloned in the pTubHA pac vector and sequenced. After stable
trophozoite transfection, immunofluoresce assays were performed.
Co-localization studies with the enzyme ADI and with the SUMO protein are a
matter of ongoing experiments. An important subject for future studies will be
to analyze if there is an association of the SUMOylated form of ADI with
importins, or with other cargo proteins, in order to crisscross the nuclear
membrane during Giardia
differentiation.