5I1U

Crystal structure of germacradien-4-ol synthase from Streptomyces citricolor


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.200 
  • R-Value Work: 0.157 
  • R-Value Observed: 0.158 

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Mechanism of Germacradien-4-ol Synthase-Controlled Water Capture.

Grundy, D.J.Chen, M.Gonzalez, V.Leoni, S.Miller, D.J.Christianson, D.W.Allemann, R.K.

(2016) Biochemistry 55: 2112-2121

  • DOI: 10.1021/acs.biochem.6b00115
  • Primary Citation of Related Structures:  
    5I1U

  • PubMed Abstract: 
  • The sesquiterpene synthase germacradiene-4-ol synthase (GdolS) from Streptomyces citricolor is one of only a few known high-fidelity terpene synthases that convert farnesyl diphosphate (FDP) into a single hydroxylated product. Crystals of unliganded GdolS-E248A diffracted to 1 ...

    The sesquiterpene synthase germacradiene-4-ol synthase (GdolS) from Streptomyces citricolor is one of only a few known high-fidelity terpene synthases that convert farnesyl diphosphate (FDP) into a single hydroxylated product. Crystals of unliganded GdolS-E248A diffracted to 1.50 Å and revealed a typical class 1 sesquiterpene synthase fold with the active site in an open conformation. The metal binding motifs were identified as D(80)DQFD and N(218)DVRSFAQE. Some bound water molecules were evident in the X-ray crystal structure, but none were obviously positioned to quench a putative final carbocation intermediate. Incubations in H2(18)O generated labeled product, confirming that the alcohol functionality arises from nucleophilic capture of the final carbocation by water originating from solution. Site-directed mutagenesis of amino acid residues from both within the metal binding motifs and without identified by sequence alignment with aristolochene synthase from Aspergillus terreus generated mostly functional germacradien-4-ol synthases. Only GdolS-N218Q generated radically different products (∼50% germacrene A), but no direct evidence of the mechanism of incorporation of water into the active site was obtained. Fluorinated FDP analogues 2F-FDP and 15,15,15-F3-FDP were potent noncompetitive inhibitors of GdolS. 12,13-DiF-FDP generated 12,13-(E)-β-farnesene upon being incubated with GdolS, suggesting stepwise formation of the germacryl cation during the catalytic cycle. Incubation of GdolS with [1-(2)H2]FDP and (R)-[1-(2)H]FDP demonstrated that following germacryl cation formation a [1,3]-hydride shift generates the final carbocation prior to nucleophilic capture. The stereochemistry of this shift is not defined, and the deuteron in the final product was scrambled. Because no clear candidate residue for binding of a nucleophilic water molecule in the active site and no significant perturbation of product distribution from the replacement of active site residues were observed, the final carbocation may be captured by a water molecule from bulk solvent.


    Organizational Affiliation

    School of Chemistry, Cardiff University , Park Place, Cardiff CF10 3AT, United Kingdom.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Germacradien-4-ol synthaseA, B335Streptomyces citricolorMutation(s): 1 
Gene Names: SC1
EC: 4.2.3
UniProt
Find proteins for G5EKM9 (Streptomyces citricolor)
Explore G5EKM9 
Go to UniProtKB:  G5EKM9
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download Ideal Coordinates CCD File 
C [auth A], D [auth B]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.200 
  • R-Value Work: 0.157 
  • R-Value Observed: 0.158 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51.369α = 90
b = 74.127β = 91.72
c = 82.489γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
SCALAdata scaling
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM56838

Revision History  (Full details and data files)

  • Version 1.0: 2016-03-30
    Type: Initial release
  • Version 1.1: 2016-04-06
    Changes: Database references
  • Version 1.2: 2016-05-04
    Changes: Database references
  • Version 1.3: 2017-09-20
    Changes: Author supporting evidence, Database references, Derived calculations
  • Version 1.4: 2019-12-25
    Changes: Author supporting evidence