CLONING AND CHARACTERIZATION OF A GENE FOR THE STAGE-SPECIFIC 82-KDA SURFACE-ANTIGEN OF METACYCLIC TRYPOMASTIGOTES OF TRYPANOSOMA-CRUZI

We have cloned and sequenced a cDNA clone coding for a metacyclic tryp omastigote-specific surface glycoprotein with a molecular mass of 82 k Da (MTS-gp82). By immunoblotting and immunoprecipitation, antibodies a gainst the recombinant protein recognized an 82-kDa protein of metacyc lic trypomastigotes, without any detectable reaction towards amastigot es, epimastigotes or tissue culture-derived trypomastigotes. The inser t of the MTS-gp82 cDNA done strongly hybridized with a single 2.2-kb m etacyclic trypomastigote mRNA, suggesting that the steady-state levels of mRNAs for MTS-gp82 are developmentally regulated. MTS-gp82 is enco ded by a multigene family whose members are distributed in several chr omosomes. Sequence analysis revealed 40-56% identity at amino acid lev el between MTS-gp82 and members of Trypanosoma cruzi gp85/sialidase fa mily (TSA-1, Tt34c1, SA85-1.1). MTS-gp82 showed several amino acid mot ifs that are characteristic of gp85/sialidase family, such as the Asp box (SxDxGxTW), the subterminal (VTVxNVFLYNR) motif and the putative G PI-anchor sequence. On the basis of its structural features, the MTS-g p82 gene could be included in the T. cruzi gp85/sialidase family, but constituting a distinct group which is preferentially expressed in met acyclic trypomastigotes.