Crystal Structure of the SpnL

Experimental Data Snapshot

  • Resolution: 3.05 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.206 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.1 of the entry. See complete history


Evidence for an Enzyme-Catalyzed Rauhut-Currier Reaction during the Biosynthesis of Spinosyn A.

Choi, S.H.Jeon, B.Kim, N.Wu, H.H.Ko, T.P.Ruszczycky, M.W.Isiorho, E.A.Liu, Y.N.Keatinge-Clay, A.T.Tsai, M.D.Liu, H.W.

(2021) J Am Chem Soc 143: 20291-20295

  • DOI: https://doi.org/10.1021/jacs.1c09482
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The catalog of enzymes known to catalyze the nucleophile-assisted formation of C-C bonds is extremely small, and there is presently no definitive example of a biological Rauhut-Currier reaction. Biosynthesis of the polyketide insecticide spinosyn A in Saccharopolyspora spinosa involves a [4 + 2]-cycloaddition and a subsequent intramolecular C-C bond formation catalyzed by SpnF and SpnL, respectively. Isotope tracer experiments and kinetic isotope effects, however, imply that the SpnL-catalyzed reaction proceeds without initial deprotonation of the substrate. The crystal structure of SpnL exhibits high similarity to SAM-dependent methyltransferases as well as SpnF. The residue Cys60 is also shown to reside in the SpnL active site, and the Cys60Ala SpnL mutant is found to be devoid of activity. Moreover, SpnL is covalently modified at Cys60 and irreversibly inactivated when it is coincubated with a fluorinated substrate analogue designed as a suicide inactivator of nucleophile-assisted C-C bond formation. These results suggest that SpnL catalyzes a biological Rauhut-Currier reaction.

  • Organizational Affiliation

    Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cyclopropane fatty-acyl-phospholipid synthase-like methyltransferase
A, B
284Saccharopolyspora spinosaMutation(s): 0 
Gene Names: A8926_6440
Find proteins for A0A2N3Y640 (Saccharopolyspora spinosa)
Explore A0A2N3Y640 
Go to UniProtKB:  A0A2N3Y640
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A2N3Y640
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.05 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.206 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 177.351α = 90
b = 177.351β = 90
c = 116.252γ = 120
Software Package:
Software NamePurpose
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Academia Sinica (Taiwan)TaiwanAS-KPQ-109-TPP2
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM 040541

Revision History  (Full details and data files)

  • Version 1.0: 2021-12-29
    Type: Initial release
  • Version 1.1: 2024-05-29
    Changes: Data collection