Steve Ealick's Research Group
Saccharomyces cerevisiae THI20
Trifunctional THI20 from Saccharomyces cerevisiae (ScTHI20) has an N-terminal HMP kinase (ThiD-like) domain and a C-terminal thiaminase II (TenA-like) domain. ThiD is involved in thiamin biosynthesis while TenA is involved in degradation. Both ThiD and TenA are now found to be involved in thiamin salvage, providing a rational for the fusion of the two disparate domains into one protein.
A relatively flexible linker region composed of a loop and a short helix joins the ThiD-like and the TenA domains. The short helices present at the N-terminus and in this linker region are the major points of interaction between thos domains.
|ScTHI20 has an overall dimeric organization in which N-terminal domains and C-terminal domains form ThiD-like and TenA-like local dimers. In the figure at left, the ThiD-like domain is at the top, while the all helical TenA-like domain is at the bottom.|
A superposition of the active-site residues of the ThiD-like domain of THI20 (green C atoms) with the active site of S. typhimurium ThiD (yellow C atoms) is show at the top of the panel. A superposition of the THI20 TenA-like active site (green C atoms) with that of B. subtilis TenA (white C atoms), which represents the part of the TenA family with conserved cysteines, is shown at the bottom of the panel.
French JB, Begley TP, and Ealick SE. Structure of trifunctional THI20 from yeast. Acta Cryst. D 67:784-791 (2011).