Steve Ealick's Research Group


Aquifex aeolicus Thiamin Monophosphate Kinase


PDB files:

3C9R, AaThiL complexed with ATP

3C9S, AaThiL complexed with AMP-PCP

3C9T, AaThiL complexed with AMP-PCP and TMP

3C9U, AaThiL complexed with ADP-TPP

Description:

Thiamin monophosphate kinase (ThiL) is the final enzyme in the thiamin biosynthesis pathway and catalyzes the ATP dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B1.  ThiL is a member of a small ATP binding superfamily that also includes the purine biosynthetic enzymes, PurM and PurL, NiFe hydrogenase maturation protein, HypE, and selenophosphate synthase, SelD. We determined the structure of ThiL from Aquifex aeolicus (AaThiL) in complex with products and a nonhydrolyzable analog AMP-PCP.

The AaThiL protomer is composed of two domains, A and B. The A domain (right) consists of the first 140 residues and adopts an α/β fold. The B domain (left), which consists of the C-terminal 160 residues, also has an α/β fold.


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ThiL exists as a dimer in which the primary interactions are hydrophobic and occur mainly in the A domain in which the twofold related β-sheets come together to form an eight stranded β-barrel.


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The AaThiL dimer has two equivalent active sites, located mostly within a single protomer but with some interactions from the opposite protomer.  The active site is located in a cleft between the A and B domains and also involves β-strands of the A domain of the twofold related protomer.  The diagram shows AMP-PCP and TMP bound.


Click the image to enlarge.

Reference:

McCulloch KM, Kinsland C, Begley TP, and Ealick SE. Structural Studies of Thiamin Monophosphate Kinase in Complex with Substrates and Products. Biochemistry 47: 3810-3821 (2008).



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