Steve Ealick's Research Group

Saccharomyces cerevisiae THI20

PDB file:



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.

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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.

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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.

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French JB, Begley TP, and Ealick SE. Structure of trifunctional THI20 from yeast. Acta Cryst. D 67:784-791 (2011).

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