Golgi bodies in the Golgi-lacking parasite Giardia lamblia

MARTÍN, MARÍA JULIA; LUJÁN, HUGO DANIEL; GARGANTINI PABLO RUBÉN

Córdoba

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

Sociedad Argentina de Investigación en Bioquímica y Biología Molecula

Giardia is a common cause of diarrheal disease. Trophozoites undergo crucial changes to survive outside the intestine by differentiating into infective cysts. Encystation entails the synthesis, transport, secretion, and assembly of cyst wall materials into a protective cyst wall. In our lab, we study the molecular events leading to cyst formation, with emphasis on vesicular transport in this parasite reported to lack a Golgi apparatus. In this work, we identified, characterized, and determined the subcellular localization of all SNAREs, ARFs, RABs, components of coatomers and many putative endoplasmic reticulum and Golgi molecules encoded in the parasite genome. Our results show that ESVs mold from the ER and that particular components of the secretory pathway localize in novel vesicles with characteristics of Golgi bodies, similar to those found in yeast. Our findings contradict the hypothesis that ESVs are Golgi-like structures and suggest that Giardia requires a small number of SNAREs, ARFs and RABs to accomplish all secretory events that are critical for growth and differentiation. We hypothesize that typical Golgi stack present in more evolved cells is missing in Giardia due to the absence of core glycosylation enzymes while the packing and sorting function of this organelle occurs in these novel Golgi bodies distributed throughout the cytoplasm of this parasitic protist.