STRUCTURE OF THE GENE ENCODING A PUTATIVE SCHISTOSOMA-MANSONI TEGUMENTAL ANTIGEN PRECURSOR

In order to obtain the complete gene encoding the putative precursor o f a 15-kDa Schistosoma mansoni tegumental antigen (Sm 1 5), two cDNAs (A70 and A184) and two fragments of independent genomic clones were su bcloned and sequenced. The collated sequence contains 4700 nucleotides and represents the full length open reading frame of the gene, encodi ng a protein of 1032 amino acids with a calculated molecular mass of 1 16 900. Thus, the gene encodes a much longer protein than that identif ied in the tegumental membranes, suggesting that it encodes a precurso r that is subsequently highly processed. A 964-bp region composed of 5 closely related repeats was found to be present within the translated frame. The predicted protein is highly acidic and there is no indicat ion of hydrophobic domains that may represent transmembrane regions or indicate attachment of a GPI anchor. The coding region has no homolog ies in the currently available data bases. In the 5' nontranscribed ar ea a copy of the SMalpha repeat family is present. The coding region i s preceded by putative CCAAT and TATA boxes that may be involved in th e control of expression.