Comparison of the structural and folding properties of two TPR domains.
Chih-Sheng Yang1, Ming-Tao Pai1, Shiou-Ru Tzeng1, Chung Wang2, Jya-Wei Cheng1
1. Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
2. Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
The tetratricopeptide repeat (TPR) motif is a protein-protein interaction module found in multiple copies in a number of functionally different proteins that facilitates specific interactions with a partner protein(s). Three-dimensional structural data have shown that the TPR motif adopts an all α-helical structure with an amphipathic channel can accommodate the complementary region of a target protein. The TPR motifs of SGT and TPR1 are little identical in sequence, but with the structures that are essentially the same. The specifics of folding of these proteins have been studied by several biophysical methods. The dimmer forms of these proteins are detectable in different approaches. The structural stabilities of TPR-SGT are found to be significantly more stable than that of TPR-TPR1. However, these proteins have both thermodynamics and kinetics instability when compared with other small proteins. The flexibility of protein, conferred by thermodynamic and kinetic instability, is also found in other α-helical repeats proteins. Thus, these features may be essential for the regulatory function that mediate a wide range of protein-protein interactions.