A Dictyostelium discoideum homologue to Tcp-1 is essential for growth and development

Tcp-1 (t-complex polypeptide 1 gene) was first identified in the mouse as relevant for tail-less and embryonic lethal phenotypes. Since then, its homologous sequences have been isolated in several other species, and the yeast Tcp-1 has been shown to encode a molecular chaperon for actin and tubulin. In a random sample of genes expressed in the gamete of Dictyostelium discoideum (Dd), we encountered a sequence containg the TCP1 motifs. The complete ORF of the gene (DdTcp-1) showed more than 60% similarity to TCP-1 of several organisms, including human. DdTcp-1 was found to be expressed in both sexually mature and immature cells at the growth phase. Although the sexual process itself was not affected, antisense interference of this gene resulted in severe retardation of cell growth, leading to the complete cessation of division. In addition, the antisense transformants stopped asexual development at the finger stage. These results suggest an important function of DdTcp-1 in growth and development of this organism.