5B5K

Crystal structure of Izumo1, the mammalian sperm ligand for egg Juno

  • Classification: CELL ADHESION
  • Organism(s): Mus musculus
  • Expression System: Homo sapiens
  • Mutation(s): No 

  • Deposited: 2016-05-11 Released: 2016-07-06 
  • Deposition Author(s): Nishimura, K., Han, L., De Sanctis, D., Jovine, L.
  • Funding Organization(s): Karolinska Institutet, Swedish Research Council, Goran Gustafsson Foundation for Research in Natural Sciences and Medicine, Sven and Ebba-Christina Hagberg foundation, EMBO Young Investigator, European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.257 
  • R-Value Observed: 0.258 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history. 


Literature

The structure of sperm Izumo1 reveals unexpected similarities with Plasmodium invasion proteins.

Nishimura, K., Han, L., Bianchi, E., Wright, G.J., de Sanctis, D., Jovine, L.

(2016) Curr Biol 26: R661-R662

  • DOI: 10.1016/j.cub.2016.06.028
  • Primary Citation of Related Structures:  
    5B5K

  • PubMed Abstract: 

    • Fertilization, the culminating event in sexual reproduction, occurs when haploid sperm and egg recognize each other and fuse to form a diploid zygote. In mammals this process critically depends on the interaction between Izumo1, a protein exposed on ...

    Fertilization, the culminating event in sexual reproduction, occurs when haploid sperm and egg recognize each other and fuse to form a diploid zygote. In mammals this process critically depends on the interaction between Izumo1, a protein exposed on the equatorial segment of acrosome-reacted sperm, and the egg plasma-membrane-anchored receptor Juno [1,2]. The molecular mechanism triggering gamete fusion is unresolved because both Izumo1 and Juno lack sequence similarity to known membrane fusogens. Here we report the crystal structure of Izumo1, which reveals a membrane distal region composed of a four-helix bundle connected to a carboxy-terminal immunoglobulin (Ig)-like domain through a β-hairpin stabilized by disulfide bonds. Remarkably, different regions of Izumo1 display significant structural similarities to two proteins expressed by the invasive sporozoite stage of Plasmodium parasites: SPECT1, which is essential for host cell traversal and hepatocyte invasion [3]; and TRAP, which is necessary for gliding motility and invasion [4]. These observations suggest a link between the molecular mechanisms underlying host cell invasion by the malaria parasite and gamete membrane fusion at fertilization.

    Related Citations: 
    • Divergent evolution of vitamin B9 binding underlies Juno-mediated adhesion of mammalian gametes.
      Han, L., Nishimura, K., Sadat Al Hosseini, H., Bianchi, E., Wright, G.J., Jovine, L.
      (2016) Curr Biol 26: R100
    • Juno is the egg Izumo receptor and is essential for mammalian fertilization.
      Bianchi, E., Doe, B., Goulding, D., Wright, G.J.
      (2014) Nature 508: 483
    • The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs.
      Inoue, N., Ikawa, M., Isotani, A., Okabe, M.
      (2005) Nature 434: 234
    Organizational Affiliation: 

    Department of Biosciences and Nutrition & Center for Innovative Medicine, Karolinska Institutet, Huddinge, SE-141 83, Sweden. Electronic address: luca.jovine@ki.se.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Izumo sperm-egg fusion protein 1A236Mus musculusMutation(s): 0 
Gene Names: Izumo1
Find proteins for Q9D9J7 (Mus musculus)
Explore Q9D9J7 
Go to UniProtKB:  Q9D9J7
Protein Feature View
Expand
 ( Mouse scroll to zoom / Hold left click to move )
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
EPE
Query on EPE
Download CCD File 
A
4-(2-HYDROXYETHYL)-1-PIPERAZINE ETHANESULFONIC ACID
C8 H18 N2 O4 S
JKMHFZQWWAIEOD-UHFFFAOYSA-N		 Ligand Interaction
NAG
Query on NAG
Download CCD File 
A
2-acetamido-2-deoxy-beta-D-glucopyranose
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.257 
  • R-Value Observed: 0.258 
  • Space Group: I 4 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 103.28α = 90
b = 103.28β = 90
c = 139.27γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
XDSdata scaling
PHASERphasing

Structure Validation

View Full Validation Report


View more in-depth experimental data

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Karolinska InstitutetSweden--
Swedish Research CouncilSweden2012-5093
Goran Gustafsson Foundation for Research in Natural Sciences and MedicineSweden--
Sven and Ebba-Christina Hagberg foundationSweden--
EMBO Young Investigator--
European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)ERC 260759

Revision History 

  • Version 1.0: 2016-07-06
    Type: Initial release
  • Version 1.1: 2016-08-03
    Changes: Database references
  • Version 1.2: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Database references, Derived calculations, Structure summary