Trypanosoma Rangeli Expresses A Gene of the Group Ii Trans-Sialidase Superfamily

0 d Trypanosoma cruzi, the etiological agent of Chagas disase, and Trypanosoma rangeli, a nonpathogenic protozoa or mammals, present surface glycoproteins of the transialidase superfamily (TSASF). According to sequence idenity, molecular weight, and function [1–3], members of SASF are classified into four groups. The first group inludes T. cruzi trans-sialidase (TcTS) and T. rangeli sialidase TrSial). TrSial expressed in T. rangeli epimastigotes forms s a strict hydrolytic enzyme that releases sialic acid residues rom the host cell surface glycoconjugates [4–6]. In contrast, . cruzi trans-sialidase transfers sialic residues from the host urface onto mucin molecules on the parasite’s surface [3]. lthough TrSial has been well characterized [4–9], its bioogical role remains unknown. Members of group II TSASF, collectively known as gp85 or gp85/trans-sialidase), are expressed in T. cruzi infective rypomastigotes forms, and intracellular amastigotes stages 1–3]. This group, which has only been described in T. cruzi, ncludes a set of heterogeneous GPI-anchored surface glycoroteins with similar molecular masses but different electrical charges. gp85/trans-sialidase proteins have been implicated in adhesion and/or internalization of the parasite to host cells [10,11], but none of its members have sialidase or transsialidase activity. In a previous work, we cloned telomeric sequences from a T. rangeli [12]. One of the recombinants obtained, namely TrTel 4 (3376 bp), had an ORF with high percent identity with all members of the gp85/trans-sialidase family at 1 kb from the telomeric end, and with the transcription sense oriented from the centromere towards the telomere. The putative 1953-bp long gene (TrGP) (Fig. 1A) encoded for 651 aminoacids (aa) putative protein with estimated mass of 71 kDa. At the nucleotide level, TrGP sequence displayed 62–67% identity (83–96% in some blocks) with T. cruzi gp85/trans-sialidase genes. In addition, the translated sequence of TrGP exhibited 45–50% identity (reaching 60% considering conservative amino acid substitutions) with proteins encoded by group II TSASF genes [10,13–17], and to a lesser degree (25–30% identity) with group I members of this superfamily, including T. rangeli sialidases (GenBank U83180, L14943). Blocks of sequence identity between TrGP