Characterization of the Complete set of SNAREs in the golgi-lacking eukaryote Giardia lamblia.

ELÍAS, ELIANA VANINA; QUIROGA, RODRIGO; GOTTIG, NATALIA; LUJÁN, HUGO DANIEL

Carlos Paz, Córdoba, Argentina.

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2008

SAIB

Giardia is an eukaryotic protozoan with unusual characteristics,such as the absence of a morphologically evident Golgi apparatus.Although both constitutive and regulated pathways for proteinsecretion exist in Giardia, little is known about the molecules andmechanisms involved in vesicular docking and fusion. In highereukaryotes, soluble N-ethylmaleimide-sensitive factor-attachmentprotein receptors (SNAREs) of the vesicle-associated membraneprotein (VAMP) and Syntaxin families play essential roles in theseprocesses. An exhaustive search of the complete Giardia genomeidentified genes for 17 SNARE proteins, some of which possessatypical amino acids at the zero layer of the SNARE domain. Theexpression and localization of all SNAREs demonstrate that specificSNAREs localize to distinct subcellular organelles. Our resultssuggest that these compartments represent the extent of theendomembrane system in eukaryotes. Comparison of GiardiaSNAREs homologous to Golgi SNAREs from other organisms doesnot allow the detection of a typical Golgi apparatus in trophozoites.Moreover, depletion of individual genes demonstrated that severalSNAREs are essential for viability. Thus, Giardia requires a smallernumber of SNAREs, compared to other eukaryotes, to accomplishall the vesicle trafficking events that are critical for growth anddifferentiation of this important human pathogen.