Protein c4 is a putative small heat shock protein in the intestinal parasite Giardia lamblia

NORES MJ,; GOTTIG N,; PRUCCA C,; CAVALLÍN L,; QUIROGA R,; CARRANZA P,; SOLARI A,; LUJÁN HD

Mar del Plata, Buenos Aires. Argentina

Congreso; XLIII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Giardia lamblia is a medical important protozoan with a low position in the eukaryotic lineage. G.lamblia trophozoites are transmited through infected hosts by differentiation into cyst forms. By screening a WB 1267 cDNA expression library, we cloned the previously isolated gene Glorf-C4, considered specific of this organism. It encodes a 22 kDa protein that assembles in 60-66 kDa and high molecular mass complexes during the whole life cycle. 66 kDa complex formations is favored under some stress conditions. C4 localizes in cytosol of trophozoites and cysts and forms large spherical aggregates when it is overexpressed, without affecting viability and encystation. No homologous proteins nor conserved domains or features arise from sequence analysis of the predicted protein. Nevertheless, C4 presents local tertiary structure similarity with the –crystallin domain of small heat shock proteins Hsp16.9B from and Triticum aestivum Hsp16.5 from the hyperthermophilic archaea Methanococcus jannaschii. Here, we discuss C4 putative role as a small heat shock protein in G.lamblia biology.