INVESTIGADORES
RIVERO Maria romina
congresos y reuniones científicas
Título:
Arginine deiminase plays multiple regulatory roles in the biology of Giardia lamblia.
Autor/es:
VRANYCH CV; RIVERO MR; TOUZ MC; ROPOLO AS
Lugar:
Mar del Plata, Buenos Aires
Reunión:
Congreso; Reunion Anual de la Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular.; 2007
Resumen:
Giardia lamblia is a food and waterborne parasite deriving from one of the earliest
branches of the eukaryotic lineage. Giardia trophozoites undergo antigenic variation, a
process by which the parasite switches its major surface molecules to evade the hosts
immune response. These variant-specific surface proteins (VSP) are membrane proteins
with a variable N-terminal extracellular region, a well-conserved hydrophobic
intramembranous domain, and a perfectly conserved 5 amino acid (CRGKA) C-terminal
tail located in the cytoplasm. Although there is extensive data related to the
characterization of VSPs, till now it is unclear how the unique structural features of
VSP contribute to the biology of Giardia. Here, we demonstrate that arginine deiminase
(gADI) binds specifically to the CRGKA cytoplasmic tail of VSPs. We found that the
function of ADI in Giardia goes beyond energy production since it is able to deiminate
protein-bound arginine and convert it to citrulline, a function restricted to higher
eukaryotes. This modification is directly related to the control of the VSP switching in
the process of antigenic variation and cell survival. Additionally, during differentiation,
gADI seems to play a regulatory role by controlling the expression of encystation
specific genes. These results define novel regulatory pathways utilized by Giardia for
survival where gADI is a key player.