3VS8

Crystal structure of type III PKS ArsC


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.76 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural basis for cyclization specificity of two Azotobacter type III polyketide synthases: a single amino acid substitution reverses their cyclization specificity

Satou, R.Miyanaga, A.Ozawa, H.Funa, N.Katsuyama, Y.Miyazono, K.Tanokura, M.Ohnishi, Y.Horinouchi, S.

(2013) J Biol Chem 288: 34146-34157

  • DOI: 10.1074/jbc.M113.487272
  • Primary Citation of Related Structures:  
    3VS8, 3VS9

  • PubMed Abstract: 
  • Type III polyketide synthases (PKSs) show diverse cyclization specificity. We previously characterized two Azotobacter type III PKSs (ArsB and ArsC) with different cyclization specificity. ArsB and ArsC, which share a high sequence identity (71%), produce alkylresorcinols and alkylpyrones through aldol condensation and lactonization of the same polyketomethylene intermediate, respectively ...

    Type III polyketide synthases (PKSs) show diverse cyclization specificity. We previously characterized two Azotobacter type III PKSs (ArsB and ArsC) with different cyclization specificity. ArsB and ArsC, which share a high sequence identity (71%), produce alkylresorcinols and alkylpyrones through aldol condensation and lactonization of the same polyketomethylene intermediate, respectively. Here we identified a key amino acid residue for the cyclization specificity of each enzyme by site-directed mutagenesis. Trp-281 of ArsB corresponded to Gly-284 of ArsC in the amino acid sequence alignment. The ArsB W281G mutant synthesized alkylpyrone but not alkylresorcinol. In contrast, the ArsC G284W mutant synthesized alkylresorcinol with a small amount of alkylpyrone. These results indicate that this amino acid residue (Trp-281 of ArsB or Gly-284 of ArsC) should occupy a critical position for the cyclization specificity of each enzyme. We then determined crystal structures of the wild-type and G284W ArsC proteins at resolutions of 1.76 and 1.99 Å, respectively. Comparison of these two ArsC structures indicates that the G284W substitution brings a steric wall to the active site cavity, resulting in a significant reduction of the cavity volume. We postulate that the polyketomethylene intermediate can be folded to a suitable form for aldol condensation only in such a relatively narrow cavity of ArsC G284W (and presumably ArsB). This is the first report on the alteration of cyclization specificity from lactonization to aldol condensation for a type III PKS. The ArsC G284W structure is significant as it is the first reported structure of a microbial resorcinol synthase.


    Organizational Affiliation

    From the Departments of Biotechnology and.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Type III polyketide synthaseA, B, C, D, E, F, G, H410Azotobacter vinelandiiMutation(s): 0 
EC: 2.3.1.74
Find proteins for C1DM33 (Azotobacter vinelandii (strain DJ / ATCC BAA-1303))
Explore C1DM33 
Go to UniProtKB:  C1DM33
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.76 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 102.318α = 90
b = 143.388β = 110.33
c = 129.623γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
SHARPphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-04-24
    Type: Initial release
  • Version 1.1: 2013-10-23
    Changes: Database references
  • Version 1.2: 2014-04-30
    Changes: Database references