CHARACTERIZATION OF THE TRYPANOSOMA-BRUCEI HOMOLOG OF A TRYPANOSOMA-CRUZI FLAGELLUM-ADHESION GLYCOPROTEIN

An immunodominant 72-kDa surface glycoprotein (Gp72) of Trypanosoma cr uzi is involved in adhesion of the flagellum to the cell body (Cooper, R, Ribeiro de Jesus, A and Cross, G.A.M (1993) J. Cell Biol. 122, 149 -156). We flagellum to the cell body (Cooper, R, Ribeiro de Jesus, A a nd Cross, G.A.M (1993) J. Cell Biol. 122 have characterized a gene, fl agellum-adhesion glycoprotein gene1 (fla1), from Trypanosoma brucei th at encodes a 546 amino-acid protein (Fla1) with high similarity to Gp7 2. Their sequence similarity and cellular localization suggest that Fl a1 and Gp72 have similar functions. We could disrupt individual fla1 a lleles but not both, suggesting that fla1 is essential in T. brucei, i n contrast to the situation for gp72 in T. cruzi. Using affinity-purif ied polyclonal antibody, raised against part of the amino-terminal dom ain of Fla1 expressed in Escherichia coli, we showed that Fla1 is conc entrated along the flagellum and in the flagellar pocket in both blood stream-form and procyclic trypanosomes. Fla1 from both life-cycle stag es is N-glycosylated. Fla1 from bloodstream-form T. brucei contains ad ditional glycans, which can be liberated by treatment with mild acid, suggestive of phosphodiester linkages.