Protein trafficking in Giardia lamblia

ZAMPONI N; SVARD S; TOUZ MC

Mar del Plata

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

SAIB

G. lamblia is an early diverging organism that parasitizes the gastrointestinal tract (GIT) of many mammals. Insidethe host, the trophozoites attaches to the intestinal cells forming a barrier that impair nutrient uptake. However, whenthe parasites reach the lower parts of the GIT, the Encystation begins with trophozoite detachment and differentiationinto cyst. During this process, the protein transport machinery adapts to sort and secret large amounts of Cyst WallMaterial (CWM) to the surface throughout regulated Encystation Specific Vesicles (ESVs). Because no recognizableGolgi apparatus is observed in this parasite, our interest was focus on the functional characterization of COPII-COPIsystem, given its importance in the ER-Golgi protein sorting and delivery. For this, we expressed the Sec23/24 ascomponent of the COPII coat and observed that the ESVs containing CWM are formed in specific COPII-enriched zones of the ER. When we analyze the COPI-associated KDEL Receptor ortholog in G. lamblia, one of thecomponent of COPI, we found that this receptor share its localization with COPII at the point of ESVs formation andunexpectedly mediates the retention of ER resident proteins during this process. Our findings showed for the firsttime a differential cellular rearrangement of the COPII/COPI machinery, acting in concert with the needs of fast andfurious protein secretion.