Steve Ealick's Research Group

Escherichia coli ThiS-ThiF complex

PDB file:

1ZUD, ThiS/ThiF complex


Thiazole biosynthesis in Bacillus subtilis involves five proteins (ThiS, ThiF, ThiG, ThiO, and IscS) and differs in the detailed mechanism of the redox and sulfur transfer chemistry from the E. coli pathway.ThiS is a 7.2 kDa protein (66 amino acids) while ThiF is a 27 kDa protein. Our crystal structure of the protein complex between ThiS and ThiF from E. coli at 2.0 Å resolution clarifies the mechanism of the sulfur transfer chemistry involved in thiazole biosynthesis. The complex was determined using the MoeB-MoaD complex (PDB code 1JW9) as a search model.

ThiS (left) is an α/β protein adopting a ubiquitin-like fold. ThiF (right) is an α/β protein consisting of an eight stranded mixed β-sheet ThiF.


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ThiS-ThiF is a heterotetramer consisting of a dimer of heterodimers. ThiF forms a central globular dimer, which is complexed with two ThiS molecules. The ThiS molecules have no contacts with each other.

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In our model, each ThiSF tetramer contains two active sites and each active site is composed of residues from both ThiF monomers. The representation shows ATP modeled into the active site.

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Lehmann C., Begley TP and Ealick SE. Structure of the Escherichia coli ThiS-ThiF complex, a key component of the sulfur transfer system in thiamin biosynthesis. Biochemistry 45:11-19 (2006).

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