Inter-Kingdom Comparative Analysis Of Translationally Controlled Tumor Protein (Tctp) Provides Clues For Their Lineage-Specific Evolution

Translationally controlled tumor protein (TCTP) is a conserved, multifunctional protein that is involved in numerous cellular processes in eukaryotes. Although the functions of TCTP have been investigated in animals, invertebrates, and plants, few lineage-specific activities of this molecule, have been reported. Here, we report the inter-kingdom comparative analysis of 625 TCTP genes from 377 eukaryotic species, including protozoa, fungi, invertebrates, vertebrates, and plants. Phylogenetic and secondary structure analyses reveal lineage-specific evolution of TCTP, and inter-kingdom comparisons highlight the lineage-specific emergence of, or changes in, secondary structure elements in TCTP proteins from different kingdoms. Furthermore, secondary structure comparisons between TCTP proteins within each kingdom, combined with measurements of the degree of sequence conservation, suggest that TCTP genes have evolved to conserve protein secondary structures in a lineage-specific manner. Additional tertiary structure analysis of TCTP-binding proteins and their interacting partners and docking simulations between these proteins further imply that TCTP gene variation may influence the tertiary structures of TCTP-binding proteins in a lineage-specific manner. Overall, our analysis suggests that TCTP has undergone lineage-specific evolution and that structural changes in TCTP proteins may affect the tertiary structure of TCTP-binding proteins and their binding partners in a lineage-specific manner.