Crystal Structure and metal binding properties of the lipoprotein MtsA

Experimental Data Snapshot

  • Resolution: 1.87 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.172 
  • R-Value Observed: 0.173 

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Crystal structure and metal binding properties of the lipoprotein MtsA, responsible for iron transport in Streptococcus pyogenes.

Sun, X.Baker, H.M.Ge, R.Sun, H.He, Q.Y.Baker, E.N.

(2009) Biochemistry 48: 6184-6190

  • DOI: https://doi.org/10.1021/bi900552c
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    An ability to acquire iron is essential for the viability and growth of almost all organisms and in pathogenic bacteria is strongly correlated with virulence. The cell surface lipoprotein MtsA, a component of the MtsABC transporter of Streptococcus pyogenes, acts as the primary receptor for inorganic iron by this significant human pathogen. Iron is bound as Fe(2+), with the participation of bicarbonate. The crystal structure of MtsA has been determined and refined at 1.8 A resolution (R = 0.167, and R(free) = 0.194). MtsA has the classic bacterial metal binding receptor (MBR) fold, with the Fe(2+) ion bound to the side chains of His68, His140, Glu206, and Asp281, at a totally enclosed site between the two domains of the protein. The absence of bicarbonate from the binding site suggests that it is displaced during the final stages of metal binding. Both the fold and metal binding site are most similar to those of the manganese receptors PsaA and MntC, consistent with the similar coordination requirements of Fe(2+) and Mn(2+). Binding studies confirm a 10-fold preference for Fe(2+) over Mn(2+), although both may be carried in vivo. Mutational analysis of the binding site shows that His140 is critical for a fully functional binding site but that Glu206 is dispensable. The crystal structure explains the distinct roles of these ligands and also reveals potential secondary binding sites that may explain the binding behavior of MtsA for metal ions other than Fe(2+).

  • Organizational Affiliation

    Institute of Life and Health Engineering and National Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, PR China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Metal ABC transporter substrate-binding lipoprotein294Streptococcus pyogenes serotype M1Mutation(s): 1 
Gene Names: mtsA
Find proteins for P0A4G4 (Streptococcus pyogenes serotype M1)
Explore P0A4G4 
Go to UniProtKB:  P0A4G4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A4G4
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on FE

Download Ideal Coordinates CCD File 
B [auth A]FE (III) ION
Experimental Data & Validation

Experimental Data

  • Resolution: 1.87 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.172 
  • R-Value Observed: 0.173 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 38.26α = 90
b = 50.077β = 90
c = 157.617γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
PDB_EXTRACTdata extraction
MAR345dtbdata collection

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-06-09
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.2: 2017-03-01
    Changes: Other
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references, Derived calculations