3BNY

X-ray Crystallographic Studies of Substrate Binding to Aristolochene Synthase Suggest a Metal Ion Binding Sequence for Catalysis

(2008) J Biol Chem 283: 15431-15439

• PubMed: 18385128 Search on PubMedSearch on PubMed Central
• 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.

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Organizational Affiliation: 

Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.