Trans-sialidase-like gene from the bloodstream form of <i>Trypanosoma evansi</i> conserves most of the active site residues and motifs found in <i>Trypanosomal sialidases</i> and trans-sialidases

Abstract

Trans-sialidase (TS) is a unique enzyme with glycosyltransferase and sialidase (SA) activities. Although many authors reported that TS is not found in the blood stream form (BSF) of African trypanosomes, SA activity has been observed in the sera of infected animals and the BSF parasites, contributing to initial and continuous anaemia. In this study, a polymerase chain reaction (PCR) based approach was used to detect a trans-sialidase gene from the bloodstream form of Trypanosoma evansi (Te) obtained from the blood of infected camels. Sequence analysis of the cloned TeTS gene indicated 99% identity to some African trypanosomes trans-sialidase genes. Unique amino acids motifs found to occur in all African trypanosomes TS genes were identified in the TeTS gene. Catalytic site residues common to SA and TS genes were identified on the catalytic region of the gene. These results indicate that TeTS is homologous to TS gene sequences and thus strongly suggests the occurrence of TS in the BSF of T. evansi.

Key words: Active-site, gene, motifs, trans-sialidase, Trypanosoma evansi.