Download MendeleyX-ray Crystallographic Studies of Substrate Binding to Aristolochene Synthase Suggest a Metal Ion Binding Sequence for Catalysis
Shishova, E.Y., Yu, F., Miller, D.J., Faraldos, J.A., Zhao, Y., Coates, R.M., Allemann, R.K., Cane, D.E., Christianson, D.W.(2008) J Biol Chem 283: 15431-15439
- PubMed: 18385128
- DOI: https://doi.org/10.1074/jbc.M800659200
- Primary Citation of Related Structures:
3BNX, 3BNY, 3CKE - PubMed Abstract:
The universal sesquiterpene precursor, farnesyl diphosphate (FPP), is cyclized in an Mg(2+)-dependent reaction catalyzed by the tetrameric aristolochene synthase from Aspergillus terreus to form the bicyclic hydrocarbon aristolochene and a pyrophosphate anion (PP(i)) coproduct. The 2.1-A resolution crystal structure determined from crystals soaked with FPP reveals the binding of intact FPP to monomers A-C, and the binding of PP(i) and Mg(2+)(B) to monomer D. The 1.89-A resolution structure of the complex with 2-fluorofarnesyl diphosphate (2F-FPP) reveals 2F-FPP binding to all subunits of the tetramer, with Mg(2+)(B)accompanying the binding of this analogue only in monomer D. All monomers adopt open activesite conformations in these complexes, but slight structural changes in monomers C and D of each complex reflect the very initial stages of a conformational transition to the closed state. Finally, the 2.4-A resolution structure of the complex with 12,13-difluorofarnesyl diphosphate (DF-FPP) reveals the binding of intact DF-FPP to monomers A-C in the open conformation and the binding of PP(i), Mg(2+)(B), and Mg(2+)(C) to monomer D in a predominantly closed conformation. Taken together, these structures provide 12 independent "snapshots" of substrate or product complexes that suggest a possible sequence for metal ion binding and conformational changes required for catalysis.
Organizational Affiliation:
Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
