2Q7A

Crystal structure of the cell surface heme transfer protein Shp


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.163 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Bis-methionyl coordination in the crystal structure of the heme-binding domain of the streptococcal cell surface protein Shp.

Aranda IV, R.Worley, C.E.Liu, M.Bitto, E.Cates, M.S.Olson, J.S.Lei, B.Phillips Jr., G.N.

(2007) J.Mol.Biol. 374: 374-383

  • DOI: 10.1016/j.jmb.2007.08.058

  • PubMed Abstract: 
  • Surface proteins Shr, Shp, and the ATP-binding cassette (ABC) transporter HtsABC are believed to make up the machinery for heme uptake in Streptococcus pyogenes. Shp transfers its heme to HtsA, the lipoprotein component of HtsABC, providing the only ...

    Surface proteins Shr, Shp, and the ATP-binding cassette (ABC) transporter HtsABC are believed to make up the machinery for heme uptake in Streptococcus pyogenes. Shp transfers its heme to HtsA, the lipoprotein component of HtsABC, providing the only experimentally demonstrated example of direct heme transfer from a surface protein to an ABC transporter in Gram-positive bacteria. To understand the structural basis of heme transfer in this system, the heme-binding domain of Shp (Shp(180)) was crystallized, and its structure determined to a resolution of 2.1 A. Shp(180) exhibits an immunoglobulin-like beta-sandwich fold that has been recently found in other pathogenic bacterial cell surface heme-binding proteins, suggesting that the mechanisms of heme acquisition are conserved. Shp shows minimal amino acid sequence identity to these heme-binding proteins and the structure of Shp(180) reveals a unique heme-iron coordination with the axial ligands being two methionine residues from the same Shp molecule. A negative electrostatic surface of protein structure surrounding the heme pocket may serve as a docking interface for heme transfer from the more basic outer cell wall heme receptor protein Shr. The crystal structure of Shp(180) reveals two exogenous, weakly bound hemins, which form a large interface between the two Shp(180) molecules in the asymmetric unit. These "extra" hemins form a stacked pair with a structure similar to that observed previously for free hemin dimers in aqueous solution. The propionates of the protein-bound heme coordinate to the iron atoms of the exogenous hemin dimer, contributing to the stability of the protein interface. Gel filtration and analytical ultracentrifugation studies indicate that both full-length Shp and Shp(180) are monomeric in dilute aqueous solution.


    Organizational Affiliation

    Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cell surface heme-binding protein
A, B
152Streptococcus pyogenesMutation(s): 1 
Gene Names: shp
Find proteins for Q06A48 (Streptococcus pyogenes)
Go to UniProtKB:  Q06A48
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GOL
Query on GOL

Download SDF File 
Download CCD File 
A, B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
HEM
Query on HEM

Download SDF File 
Download CCD File 
A, B
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.163 
  • Space Group: P 65
Unit Cell:
Length (Å)Angle (°)
a = 82.317α = 90.00
b = 82.317β = 90.00
c = 106.054γ = 120.00
Software Package:
Software NamePurpose
DENZOdata reduction
PDB_EXTRACTdata extraction
SHARPphasing
HKL-2000data reduction
HKL-2000data collection
REFMACrefinement
HKL-2000data scaling
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-09-18
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Derived calculations, Version format compliance
  • Version 1.2: 2017-10-18
    Type: Refinement description