Steve Ealick's Research Group
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Steve Ealick's Research Group |
Methanobacterium thermoautotrophicum PurO
PDB files:
2NTM, unliganded PurO
2NTK, PurO/IMP
2NTL, PurO/AICAR
Description:
Inosine 5′-monophosphate (IMP) cyclohydrolase catalyzes the cyclization of 5-formaminoimidazole-4-carboxamide ribonucleotide (FAICAR) to IMP in the final step of de novo purine biosynthesis. In Archaea PurO performs this function while PurH is the enzyme in Bacteria.
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The Methanobacterium thermoautotrophicum PurO (MthPurO) monomer adopts an NTN hydrolase fold showing a four-layered α-β-β-α core structure with two antiparallel β-sheets packed against each other covered by α-helices.
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Click the images to enlarge. |
| MthPurO exists as a box-shaped tetramer, both in solution and in the crystal form P32 that we analyzed.The monomers are arranged so that each makes contacts with the other three monomers. |
Click the image to enlarge. |
The IMP molecule is bound at the deep pocket between
the two central central b-sheets. All amino
acid residues in the pocket are absolutely conserved within
all PurO sequences. Dashed lines indicate the hydrogen bonds. |
Click the image to enlarge. |
Reference:
Kang, Y.-N., Tran, A., White, R. H., and Ealick, S. E. A Novel Function for the NTN Hydrolase Fold Demonstrated by the Structure of an Archeal Inosine Monophosphate Cyclohydrolase, Biochemistry 46:5050-5062 (2007).
