Crystal structure of the (BACCR)NAT3 arylamine N-acetyltransferase from Bacillus cereus reveals a unique Cys-His-Glu catalytic triad

Experimental Data Snapshot

  • Resolution: 2.14 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.205 

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This is version 1.4 of the entry. See complete history


Structural and Biochemical Characterization of an Active Arylamine N-Acetyltransferase Possessing a Non-canonical Cys-His-Glu Catalytic Triad.

Kubiak, X.Li de la Sierra-Gallay, I.Chaffotte, A.F.Pluvinage, B.Weber, P.Haouz, A.Dupret, J.M.Rodrigues-Lima, F.

(2013) J Biol Chem 288: 22493-22505

  • DOI: https://doi.org/10.1074/jbc.M113.468595
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Arylamine N-acetyltransferases (NATs), a class of xenobiotic-metabolizing enzymes, catalyze the acetylation of aromatic amine compounds through a strictly conserved Cys-His-Asp catalytic triad. Each residue is essential for catalysis in both prokaryotic and eukaryotic NATs. Indeed, in (HUMAN)NAT2 variants, mutation of the Asp residue to Asn, Gln, or Glu dramatically impairs enzyme activity. However, a putative atypical NAT harboring a catalytic triad Glu residue was recently identified in Bacillus cereus ((BACCR)NAT3) but has not yet been characterized. We report here the crystal structure and functional characterization of this atypical NAT. The overall fold of (BACCR)NAT3 and the geometry of its Cys-His-Glu catalytic triad are similar to those present in functional NATs. Importantly, the enzyme was found to be active and to acetylate prototypic arylamine NAT substrates. In contrast to (HUMAN) NAT2, the presence of a Glu or Asp in the triad of (BACCR)NAT3 did not significantly affect enzyme structure or function. Computational analysis identified differences in residue packing and steric constraints in the active site of (BACCR)NAT3 that allow it to accommodate a Cys-His-Glu triad. These findings overturn the conventional view, demonstrating that the catalytic triad of this family of acetyltransferases is plastic. Moreover, they highlight the need for further study of the evolutionary history of NATs and the functional significance of the predominant Cys-His-Asp triad in both prokaryotic and eukaryotic forms.

  • Organizational Affiliation

    Université Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative, CNRS EAC4413, 75013 Paris, France.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
N-hydroxyarylamine O-acetyltransferase
A, B
265Bacillus cereus ATCC 14579Mutation(s): 0 
Gene Names: BC_3483NAT3
Find proteins for Q81AS3 (Bacillus cereus (strain ATCC 14579 / DSM 31 / CCUG 7414 / JCM 2152 / NBRC 15305 / NCIMB 9373 / NCTC 2599 / NRRL B-3711))
Explore Q81AS3 
Go to UniProtKB:  Q81AS3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ81AS3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.14 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.205 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 90.43α = 90
b = 44.52β = 103.8
c = 132.97γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XDSdata scaling
RemDAqdata collection

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-06-26
    Type: Initial release
  • Version 1.1: 2013-07-03
    Changes: Database references
  • Version 1.2: 2013-08-21
    Changes: Database references
  • Version 1.3: 2019-07-17
    Changes: Data collection, Refinement description
  • Version 1.4: 2023-09-13
    Changes: Data collection, Database references, Derived calculations, Refinement description