Crystal Structure of UDP-N-acetylmuramic acid:L-alanine Ligase (MurC) from Haemophilus influenzae

Experimental Data Snapshot

  • Resolution: 1.85 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.171 

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Crystal Structures of Active Fully Assembled Substrate- and Product-Bound Complexes of UDP-N-Acetylmuramic Acid:L-Alanine Ligase (MurC) from Haemophilus influenzae.

Mol, C.D.Brooun, A.Dougan, D.R.Hilgers, M.T.Tari, L.W.Wijnands, R.A.Knuth, M.W.McRee, D.E.Swanson, R.V.

(2003) J Bacteriol 185: 4152-4162

  • DOI: https://doi.org/10.1128/JB.185.14.4152-4162.2003
  • Primary Citation of Related Structures:  
    1P31, 1P3D

  • PubMed Abstract: 

    UDP-N-acetylmuramic acid:L-alanine ligase (MurC) catalyzes the addition of the first amino acid to the cytoplasmic precursor of the bacterial cell wall peptidoglycan. The crystal structures of Haemophilus influenzae MurC in complex with its substrate UDP-N-acetylmuramic acid (UNAM) and Mg(2+) and of a fully assembled MurC complex with its product UDP-N-acetylmuramoyl-L-alanine (UMA), the nonhydrolyzable ATP analogue AMPPNP, and Mn(2+) have been determined to 1.85- and 1.7-A resolution, respectively. These structures reveal a conserved, three-domain architecture with the binding sites for UNAM and ATP formed at the domain interfaces: the N-terminal domain binds the UDP portion of UNAM, and the central and C-terminal domains form the ATP-binding site, while the C-terminal domain also positions the alanine. An active enzyme structure is thus assembled at the common domain interfaces when all three substrates are bound. The MurC active site clearly shows that the gamma-phosphate of AMPPNP is positioned between two bound metal ions, one of which also binds the reactive UNAM carboxylate, and that the alanine is oriented by interactions with the positively charged side chains of two MurC arginine residues and the negatively charged alanine carboxyl group. These results indicate that significant diversity exists in binding of the UDP moiety of the substrate by MurC and the subsequent ligases in the bacterial cell wall biosynthesis pathway and that alterations in the domain packing and tertiary structure allow the Mur ligases to bind sequentially larger UNAM peptide substrates.

  • Organizational Affiliation

    Syrrx Inc., San Diego, California 92121, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
UDP-N-acetylmuramate--alanine ligase
A, B
475Haemophilus influenzaeMutation(s): 15 
Gene Names: murC
Find proteins for P45066 (Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd))
Explore P45066 
Go to UniProtKB:  P45066
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP45066
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.85 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.171 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 91.523α = 90
b = 92.274β = 90
c = 118.174γ = 90
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-07-15
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance