Eimeria tenella: cloning and characterization of cDNA encoding a S3a ribosomal protein.

A lambda Zap II cDNA library was constructed from Eimeria tenella first- generation schizonts mRNA and screened with a mouse serum raised against this parasitic stage. This serum identified a clone encoding a S3a ribosomal protein (EtS3a). The 858-bp cDNA fragment, containing the entire parasitic gene encoded a highly basic protein of 264 amino acids (aa) with a molecular weight of 29.780kDa. Based upon amino acid sequence comparison, EtS3a is highly homologous to v-fos transformation effector (encoded by the fte-1 gene) and cyc-07 (a plant homologue of fte-1) and similar to the yeast MFT1 (encoded by the mitochondrial fusion targeting gene). The expressions of mammalian fte-1, plant cyc-07 and yeast MFT1 have all been shown to be cell-cycle-regulated and involved in protein synthesis at the level of the ribosome. Since EtS3a expression is also developmentally regulated, we suggest that this gene product is a functional homologue of fte-1, cyc-07 and MFT1 and an important molecule regulating the development of Eimeria tenella.