Molecular cloning, expression profiles and characterization of a novel translationally controlled tumor protein in rubber tree (Hevea brasiliensis)

The translationally controlled tumor protein (TCTP) is a multi-functioning protein that carries out vital roles in various life processes. In this study, a new TCTP gene, designated as HbTCTP1, was isolated in Hevea brasiliensis. The full-length complementary DNA (cDNA) of HbTCTP1 contained a maximum open reading frame (ORF) of 507 base pair (bp) encoding 168 amino acids. The sequence comparison showed that the deduced HbTCTP1 indicated high identities to plant TCTP proteins, and clustered in the dicot cluster of plant TCTPs. Although HbTCTP1 and human TCTP proteins did not parallel in overall sequence similarity, they indicated highly similar 3D structures with a nearly identical spatial organization of α-helices, β-sheets, and coil regions. Real time reverse-transcription PCR (RT-PCR) analyses showed that HbTCTP1 was expressed throughout different tissues and developmental stages of leaves. Besides being related to tapping panel dryness (TPD), the HbTCTP1 transcripts were regulated by various treatments, including drought, low temperature, high salt, ethrel (ET), wounding, H2O2, and methyl jasmonate (Me-JA) treatments. The recombinant HbTCTP1 fusion protein was shown to protect supercoiled plasmid DNA from damages induced by metal-catalyzed generation of reactive oxygen species. The 45Ca2+-overlay assay showed that HbTCTP1 was a calcium-binding protein. Our results are greatly helpful in understanding the molecular characterization and expression profiles of HbTCTP1, and lay the foundation for further analyzing the function of HbTCTP1 in rubber tree.