Crystal structure of muconate lactonizing enzyme from Mucobacterium Smegmatis complexed with muconolactone

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.201 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 

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Evolution of enzymatic activities in the enolase superfamily: stereochemically distinct mechanisms in two families of cis,cis-muconate lactonizing enzymes

Sakai, A.Fedorov, A.A.Fedorov, E.V.Schnoes, A.M.Glasner, M.E.Brown, S.Rutter, M.E.Bain, K.Chang, S.Gheyi, T.Sauder, J.M.Burley, S.K.Babbitt, P.C.Almo, S.C.Gerlt, J.A.

(2009) Biochemistry 48: 1445-1453

  • DOI: https://doi.org/10.1021/bi802277h
  • Primary Citation of Related Structures:  
    3CT2, 3DG3, 3DG6, 3DG7, 3DGB, 3FJ4

  • PubMed Abstract: 

    The mechanistically diverse enolase superfamily is a paradigm for elucidating Nature's strategies for divergent evolution of enzyme function. Each of the different reactions catalyzed by members of the superfamily is initiated by abstraction of the alpha-proton of a carboxylate substrate that is coordinated to an essential Mg(2+). The muconate lactonizing enzyme (MLE) from Pseudomonas putida, a member of a family that catalyzes the syn-cycloisomerization of cis,cis-muconate to (4S)-muconolactone in the beta-ketoadipate pathway, has provided critical insights into the structural bases for evolution of function within the superfamily. A second, divergent family of homologous MLEs that catalyzes anti-cycloisomerization has been identified. Structures of members of both families liganded with the common (4S)-muconolactone product (syn, Pseudomonas fluorescens, gi 70731221 ; anti, Mycobacterium smegmatis, gi 118470554 ) document that the conserved Lys at the end of the second beta-strand in the (beta/alpha)(7)beta-barrel domain serves as the acid catalyst in both reactions. The different stereochemical courses (syn and anti) result from different structural strategies for determining substrate specificity: although the distal carboxylate group of the cis,cis-muconate substrate attacks the same face of the proximal double bond, opposite faces of the resulting enolate anion intermediate are presented to the conserved Lys acid catalyst. The discovery of two families of homologous, but stereochemically distinct, MLEs likely provides an example of "pseudoconvergent" evolution of the same function from different homologous progenitors within the enolase superfamily, in which different spatial arrangements of active site functional groups and substrate specificity determinants support catalysis of the same reaction.

  • Organizational Affiliation

    Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Muconate cycloisomerase367Mycolicibacterium smegmatis MC2 155Mutation(s): 0 
EC: 5.5.1
Find proteins for A0QTN8 (Mycolicibacterium smegmatis (strain ATCC 700084 / mc(2)155))
Explore A0QTN8 
Go to UniProtKB:  A0QTN8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0QTN8
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on MUC

Download Ideal Coordinates CCD File 
C [auth A][(2S)-5-oxo-2,5-dihydrofuran-2-yl]acetic acid
C6 H6 O4
Query on MG

Download Ideal Coordinates CCD File 
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.201 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 
  • Space Group: I 4 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 123.84α = 90
b = 123.84β = 90
c = 117.37γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-03-03
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.2: 2021-02-03
    Changes: Database references, Derived calculations
  • Version 1.3: 2024-03-20
    Changes: Data collection, Database references