Crystal structure of putrescine transcarbamylase from Enterococcus faecalis lacking its C-terminal Helix, with bound N5-(phosphonoacetyl) -L-ornithine

Experimental Data Snapshot

  • Resolution: 1.59 Å
  • R-Value Free: 0.180 
  • R-Value Work: 0.162 
  • R-Value Observed: 0.163 

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New Insight Into the Transcarbamylase Family: The Structure of Putrescine Transcarbamylase, a Key Catalyst for Fermentative Utilization of Agmatine

Polo, L.M.Gil-Ortiz, F.Cantin, A.Rubio, V.

(2012) PLoS One 7: 31528

  • DOI: https://doi.org/10.1371/journal.pone.0031528
  • Primary Citation of Related Structures:  
    4A8H, 4A8P, 4A8T

  • PubMed Abstract: 

    Transcarbamylases reversibly transfer a carbamyl group from carbamylphosphate (CP) to an amine. Although aspartate transcarbamylase and ornithine transcarbamylase (OTC) are well characterized, little was known about putrescine transcarbamylase (PTC), the enzyme that generates CP for ATP production in the fermentative catabolism of agmatine. We demonstrate that PTC (from Enterococcus faecalis), in addition to using putrescine, can utilize L-ornithine as a poor substrate. Crystal structures at 2.5 Å and 2.0 Å resolutions of PTC bound to its respective bisubstrate analog inhibitors for putrescine and ornithine use, N-(phosphonoacetyl)-putrescine and δ-N-(phosphonoacetyl)-L-ornithine, shed light on PTC preference for putrescine. Except for a highly prominent C-terminal helix that projects away and embraces an adjacent subunit, PTC closely resembles OTCs, suggesting recent divergence of the two enzymes. Since differences between the respective 230 and SMG loops of PTC and OTC appeared to account for the differential preference of these enzymes for putrescine and ornithine, we engineered the 230-loop of PTC to make it to resemble the SMG loop of OTCs, increasing the activity with ornithine and greatly decreasing the activity with putrescine. We also examined the role of the C-terminal helix that appears a constant and exclusive PTC trait. The enzyme lacking this helix remained active but the PTC trimer stability appeared decreased, since some of the enzyme eluted as monomers from a gel filtration column. In addition, truncated PTC tended to aggregate to hexamers, as shown both chromatographically and by X-ray crystallography. Therefore, the extra C-terminal helix plays a dual role: it stabilizes the PTC trimer and, by shielding helix 1 of an adjacent subunit, it prevents the supratrimeric oligomerizations of obscure significance observed with some OTCs. Guided by the structural data we identify signature traits that permit easy and unambiguous annotation of PTC sequences.

  • Organizational Affiliation

    Instituto de Biomedicina de Valencia and Centro de Investigación Biomédica en Red de Enfermedades Raras, Valencia, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
PUTRESCINE CARBAMOYLTRANSFERASE339Enterococcus faecalisMutation(s): 0 
Find proteins for Q837U7 (Enterococcus faecalis (strain ATCC 700802 / V583))
Explore Q837U7 
Go to UniProtKB:  Q837U7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ837U7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.59 Å
  • R-Value Free: 0.180 
  • R-Value Work: 0.162 
  • R-Value Observed: 0.163 
  • Space Group: P 63 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 89.99α = 90
b = 89.99β = 90
c = 184.32γ = 120
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata 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: 2012-02-15
    Type: Initial release
  • Version 1.1: 2012-03-14
    Changes: Other
  • Version 1.2: 2023-12-20
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description