THE PROTOZOAN TRYPANOSOMA-CRUZI HAS A FAMILY OF GENES RESEMBLING THE MUCIN GENES OF MAMMALIAN-CELLS

Mucins are heavily O-glycosylated Thr/Ser/Pro-rich molecules. Given th eir relevant functions, mucins and their genes have been mainly studie d in higher eukaryotes. In the protozoan parasite Trypanosoma cruzi, m ucin-like glycoproteins were shown to play an important role in the in teraction with the surface of the mammalian cell during the invasion p rocess, We show now that this parasite has a family of putative mucin genes, whose organization resembles the one present in mammalian cells . Different parasite isolates have different sets of genes, as defined by their central domain. Central domains, rich in codons for Thr and/ or Ser and Pro residues, are made up of either a variable number of re peat units in tandem or non-repetitive sequences. Conversely, 5'- and 3'-ends from different genes in different isolates have similar sequen ces, suggesting their common origin. Comparison of deduced amino acid sequences revealed that all members of the family have the same putati ve signal peptide on the N terminus and a putative sequence for glycop hosphatidylinositol anchoring on the C terminus. The deduced molecular mass of the core proteins is small (from 17 to 21 kDa), in agreement with the 1-kilobase size of the mRNA detected. Putative mucin genes in T. cruzi are located on large chromosomal bands of about 1.6-2.2 mega base pairs.