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

DIEGO NICOLÁS RÍOS; PABLO RUBÉN GARGANTINI; ALBANO HERALDO TENAGLIA; HUGO DANIEL LUJÁN; MARÍA JULIA MARTIN

Córdoba

Congreso; 52th Annual Meeting Argentine Society for Biochemistry and Molecular Biology (SAIB); 2016

SAIB

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