Trypanosoma cruzi: A gene family encoding chitin-binding-like proteins is posttranscriptionally regulated during metacyclogenesis

The development of the representation of differential expression method has lead to the cloning of Trypanosoma cruzi stage-specific genes. We used thi s method to characterize a multicopy gene family differentially expressed d uring metacyclogenesis. The genomic and cDNA clones sequenced encoded three short cysteine-rich polypeptides, of two types, with predicted molecular m asses of 7.1, 10.4, and 10.9 kDa. We searched GenBank for similar sequences and found that the sequences of these clones were similar to that encoding the wheat germ agglutinin protein. The region of similarity corresponds to the chitin-binding domain, with eight similarly positioned half-cysteines and conserved aromatic residues involved in chitin recognition. Multiple co pies of the genes of this family are present on a high-molecular-mass chrom osome. We studied the expression of genes of this family during metacycloge nesis by determining messenger RNA (mRNA) levels. The mRNAs for the members of this gene family were present in the total RNA fraction but were mobili zed to the polysomal fraction of adhered (differentiating) epimastigotes du ring metacyclogenesis, with a peak of accumulation at 24 of differentiation . Polyclonal antisera were raised against a recombinant protein and a synth etic peptide. The specific sera obtained detected 7- and 11-kDa proteins in T. cruzi total protein extracts. The 11-kDa protein was present in similar amounts in the various cell populations, whereas the 7-kDa protein display ed differential synthesis during metacyclogenesis, with maximal levels in 2 4-h-adhered (differentiating) epimastigotes. (C) 2001 Academic Press.