Structure of the A domain of carboxylic acid reductase (CAR) from Nocardia iowensis in complex with AMP and benzoic acid

Experimental Data Snapshot

  • Resolution: 1.71 Å
  • R-Value Free: 0.215 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.182 

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Structures of carboxylic acid reductase reveal domain dynamics underlying catalysis.

Gahloth, D.Dunstan, M.S.Quaglia, D.Klumbys, E.Lockhart-Cairns, M.P.Hill, A.M.Derrington, S.R.Scrutton, N.S.Turner, N.J.Leys, D.

(2017) Nat Chem Biol 13: 975-981

  • DOI: https://doi.org/10.1038/nchembio.2434
  • Primary Citation of Related Structures:  
    5MSC, 5MSD, 5MSO, 5MSP, 5MSR, 5MSS, 5MST, 5MSU, 5MSV, 5MSW

  • PubMed Abstract: 

    Carboxylic acid reductase (CAR) catalyzes the ATP- and NADPH-dependent reduction of carboxylic acids to the corresponding aldehydes. The enzyme is related to the nonribosomal peptide synthetases, consisting of an adenylation domain fused via a peptidyl carrier protein (PCP) to a reductase termination domain. Crystal structures of the CAR adenylation-PCP didomain demonstrate that large-scale domain motions occur between the adenylation and thiolation states. Crystal structures of the PCP-reductase didomain reveal that phosphopantetheine binding alters the orientation of a key Asp, resulting in a productive orientation of the bound nicotinamide. This ensures that further reduction of the aldehyde product does not occur. Combining crystallography with small-angle X-ray scattering (SAXS), we propose that molecular interactions between initiation and termination domains are limited to competing PCP docking sites. This theory is supported by the fact that (R)-pantetheine can support CAR activity for mixtures of the isolated domains. Our model suggests directions for further development of CAR as a biocatalyst.

  • Organizational Affiliation

    Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, UK.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Carboxylic acid reductase1,174Nocardia iowensisMutation(s): 0 
Gene Names: car
EC: 1.2.1 (PDB Primary Data), (PDB Primary Data)
Find proteins for Q6RKB1 (Nocardia iowensis)
Explore Q6RKB1 
Go to UniProtKB:  Q6RKB1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ6RKB1
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on AMP

Download Ideal Coordinates CCD File 
C10 H14 N5 O7 P
Query on BEZ

Download Ideal Coordinates CCD File 
C7 H6 O2
Experimental Data & Validation

Experimental Data

  • Resolution: 1.71 Å
  • R-Value Free: 0.215 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.182 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 52.65α = 93.37
b = 54.499β = 97.68
c = 66.365γ = 102.44
Software Package:
Software NamePurpose
XDSdata reduction
XDSdata 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: 2017-07-05
    Type: Initial release
  • Version 1.1: 2017-07-12
    Changes: Database references
  • Version 1.2: 2017-07-26
    Changes: Database references
  • Version 1.3: 2017-08-30
    Changes: Database references
  • Version 1.4: 2019-10-16
    Changes: Data collection
  • Version 1.5: 2024-01-17
    Changes: Data collection, Database references, Refinement description