4E82

Crystal structure of monomeric variant of human alpha-defensin 5, HD5 (Glu21EMe mutant)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.170 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Functional determinants of human enteric {alpha}-defensin HD5: crucial role for hydrophobicity at dimer interface.

Rajabi, M.Ericksen, B.Wu, X.de Leeuw, E.Zhao, L.Pazgier, M.Lu, W.

(2012) J.Biol.Chem. 287: 21615-21627

  • DOI: 10.1074/jbc.M112.367995
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Human α-defensins are cationic peptides that self-associate into dimers and higher-order oligomers. They bind protein toxins, such as anthrax lethal factor (LF), and kill bacteria, including Escherichia coli and Staphylococcus aureus, among other fun ...

    Human α-defensins are cationic peptides that self-associate into dimers and higher-order oligomers. They bind protein toxins, such as anthrax lethal factor (LF), and kill bacteria, including Escherichia coli and Staphylococcus aureus, among other functions. There are six members of the human α-defensin family: four human neutrophil peptides, including HNP1, and two enteric human defensins, including HD5. We subjected HD5 to comprehensive alanine scanning mutagenesis. We then assayed LF binding by surface plasmon resonance, LF activity by enzyme kinetic inhibition, and antibacterial activity by the virtual colony count assay. Most mutations could be tolerated, resulting in activity comparable with that of wild type HD5. However, the L29A mutation decimated LF binding and bactericidal activity against Escherichia coli and Staphylococcus aureus. A series of unnatural aliphatic and aromatic substitutions at position 29, including aminobutyric acid (Abu) and norleucine (Nle) correlated hydrophobicity with HD5 function. The crystal structure of L29Abu-HD5 depicted decreased hydrophobic contacts at the dimer interface, whereas the Nle-29-HD5 crystal structure depicted a novel mode of dimerization with parallel β strands. The effect of mutating Leu(29) is similar to that of a C-terminal hydrophobic residue of HNP1, Trp(26). In addition, in order to further clarify the role of dimerization in HD5 function, an obligate monomer was generated by N-methylation of the Glu(21) residue, decreasing LF binding and antibacterial activity against S. aureus. These results further characterize the dimer interface of the α-defensins, revealing a crucial role of hydrophobicity-mediated dimerization.


    Organizational Affiliation

    Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Defensin-5
A, B
32Homo sapiensMutation(s): 0 
Gene Names: DEFA5 (DEF5)
Find proteins for Q01523 (Homo sapiens)
Go to Gene View: DEFA5
Go to UniProtKB:  Q01523
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
EME
Query on EME
A, B
L-PEPTIDE LINKINGC6 H11 N O4GLU
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.170 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 22.317α = 90.00
b = 37.733β = 90.00
c = 59.852γ = 90.00
Software Package:
Software NamePurpose
PHASERphasing
REFMACrefinement
PDB_EXTRACTdata extraction
SCALEPACKdata scaling
HKL-2000data collection
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2012-03-19 
  • Released Date: 2012-05-16 
  • Deposition Author(s): Pazgier, M.

Revision History 

  • Version 1.0: 2012-05-16
    Type: Initial release
  • Version 1.1: 2013-06-19
    Type: Database references