The Traffic Of Soluble Hydrolases Is Mediated By Vps10p-Like Receptor In Giardia lamblia

SILVANA L. MIRAS; MARIA R. RIVERO; RODRIGO QUIROGA; NAHUEL ZAMPONI; CONSTANZA FELIZIANI; ANDREA S. RÓPOLO; MARIA C. TOUZ

Potrero de Funes

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2011

XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

The targeting of lysosomal enzymes to their final destination is directed by a series of protein and recognition signals. Although, Giardia lamblia lacks a recognized Golgi apparatus or a typical endosome/lysosome system, it might have a specific and conserved mechanism by means the soluble hydrolases are sorted. In this work, we describe the presence of a Vps10p -like receptor and its function in sorting of lysosomal enzymes. Bioinformatics and proteinase K assays allowed us to determine that the gVps10p receptor is a type I transmembrana protein with a WD40 motif in the luminal portion and a cytoplasmic tyrosine motif (YQII). Immunoblot assay showed a ̃60 kDa but also a ̃120 kDa band, possibly related to dimerization. IFA and confocal microscopy of trophozoites expressing gVps10p- HA fusion protein, showed that it localize around the nuclei colocalizing with the endoplasmic reticulum 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. 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. This work will contribute to understand how the endosomal/lysosomal pathway works in the early divergent parasite G. lamblia.