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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1qfe

E.C. name3-dehydroquinate dehydratase
SpeciesSalmonella typhi (Bacteria)
E.C. Number (IntEnz) 4.2.1.10
CSA Homologues of 1qfeThere are 11 Homologs
CSA Entries With UniProtID P24670
CSA Entries With EC Number 4.2.1.10
PDBe Entry 1qfe
PDBSum Entry 1qfe
MACiE Entry M0054

Literature Report

Introduction3-dehydroquinate dehydratase catalyses the third step in the biosynthesis of chorismate within the Shikimate pathway which synthesises aromatic compounds as well as in the degradative quinate pathway. It is a type I dehydroquinase which catalyses a cis-dehydration of the hexane ring of 3-dehydroquinate via a covalent imine intermediate (unlike the type II dehydroquinase which catalyses a trans-dehydration via an enolate intermediate). Type I dehydroquinases use a Schiff base mechanism. The pathway is essential in microorganisms and plants for the biosynthesis of compounds such as folate, ubiquinone and aromatic amino acids. The absence of this pathway in animals makes it an attractive target for antimicrobial agents.
MechansimHis143 is thought to play a part as a general acid in the formation of a Schiff base: a covalent adduct between the substrate and Lys170 of the enzyme. The role of the Schiff base is to act as an electron sink . It may also play a role in distorting the carbocyclic ring of dehydroquinate to render it more reactive. His143 is then thought to play a role in proton abstraction. Glu86 is positioned to interact with His143 and orientate it in a manner reminiscent of the serine proteases to allow it to act as a general base and abstract the C2 proton. However it is worth noting that recent research has put some doubt on this role. Any attack on the substrate from below is prevented by a beta-hairpin so only cis-elimination is possible.
Reaction

Catalytic Sites for 1qfe

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysA170170macie:sideChain
HisA143143macie:sideChain
GluA8686macie:sideChain

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysB170170macie:sideChain
HisB143143macie:sideChain
GluB8686macie:sideChain

Literature References

Notes:
Leech AP
Re-evaluating the role of His-143 in the mechanism of type I dehydroquinase from Escherichia coli using two-dimensional 1H,13C NMR.
J Biol Chem 1998 273 9602-9607
PubMed: 9545291
Gourley DG
The two types of 3-dehydroquinase have distinct structures but catalyze the same overall reaction.
Nat Struct Biol 1999 6 521-525
PubMed: 10360352
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