ANTIGENIC VARIATION IN GIARDIA LAMBLIA: ROLE OF VSPS TRANSMEMBRANE DOMAIN IN SENSING AND SIGNALING

RIOS DIEGO N.; GARGANTINI PABLO RUBÉN; TENAGLIA ALBANO H.; LUJAN HUGO DANIEL; MARTIN, MARÌA JULIA

Cordoba

Congreso; SAIB; 2016

SAIB

Giardia lambliatrophozoites undergo antigenic variation, where one member of the Variant-specific Surface Protein (VSP) family is expressed on the surface of proliferating trophozoites and periodically replaced by another. VSPs comprise an N-terminal variable domain and a highly conserved C-terminal region that includes a hydrophobic transmembrane domain (TMD) and a short cytoplasmic CRGKA tail. Despite the high degree of conservation, the VSP TMD has received relatively little attention, possibly due to the fact that TMDs have often been viewed as passive anchor sequences that span the lipid bilayer. Accumulating evidence has implicated TMDs in helix-helix interactions leading to dimerization and signal transduction. We have carried out TOXCAT assays to assess the ability of VSP TMDs to self-interact and found that mutations of highly conserved aminoacids within this sequence can alter VSP TMD interactions. Our results suggest that dimerization of VSPs via their TMDs play a role in the mechanism of signal transduction in antibody-triggered antigenic variation.