The alpha-esterase-7 carboxylesterase, E3, from the blowfly Lucilia cuprina

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.171 

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Structure and function of an insect alpha-carboxylesterase ( alpha Esterase7) associated with insecticide resistance.

Jackson, C.J.Liu, J.W.Carr, P.D.Younus, F.Coppin, C.Meirelles, T.Lethier, M.Pandey, G.Ollis, D.L.Russell, R.J.Weik, M.Oakeshott, J.G.

(2013) Proc Natl Acad Sci U S A 110: 10177-10182

  • DOI: https://doi.org/10.1073/pnas.1304097110
  • Primary Citation of Related Structures:  
    4FNG, 4FNM

  • PubMed Abstract: 

    Insect carboxylesterases from the αEsterase gene cluster, such as αE7 (also known as E3) from the Australian sheep blowfly Lucilia cuprina (LcαE7), play an important physiological role in lipid metabolism and are implicated in the detoxification of organophosphate (OP) insecticides. Despite the importance of OPs to agriculture and the spread of insect-borne diseases, the molecular basis for the ability of α-carboxylesterases to confer OP resistance to insects is poorly understood. In this work, we used laboratory evolution to increase the thermal stability of LcαE7, allowing its overexpression in Escherichia coli and structure determination. The crystal structure reveals a canonical α/β-hydrolase fold that is very similar to the primary target of OPs (acetylcholinesterase) and a unique N-terminal α-helix that serves as a membrane anchor. Soaking of LcαE7 crystals in OPs led to the capture of a crystallographic snapshot of LcαE7 in its phosphorylated state, which allowed comparison with acetylcholinesterase and rationalization of its ability to protect insects against the effects of OPs. Finally, inspection of the active site of LcαE7 reveals an asymmetric and hydrophobic substrate binding cavity that is well-suited to fatty acid methyl esters, which are hydrolyzed by the enzyme with specificity constants (∼10(6) M(-1) s(-1)) indicative of a natural substrate.

  • Organizational Affiliation

    Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia. cjackson@rsc.anu.edu.au

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
E3 alpha-esterase-7 carboxylesterase569Lucilia cuprinaMutation(s): 6 
Gene Names: LcaE7
Find proteins for Q25252 (Lucilia cuprina)
Explore Q25252 
Go to UniProtKB:  Q25252
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ25252
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on DPF

Download Ideal Coordinates CCD File 
C4 H11 O4 P
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.171 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.65α = 90
b = 102.74β = 90
c = 226.4γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-12-04
    Type: Initial release
  • Version 1.1: 2023-09-13
    Changes: Data collection, Database references, Derived calculations, Refinement description