Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Standalone Viewers  
Protein Workshop | Ligand Explorer

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 27791.83 
• Atom Count: 1932 
• Residue Count: 236 
• Unique protein chains: 1

5B5K

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

• DOI: 10.2210/pdb5B5K/pdb

• Classification: CELL ADHESION
• Organism(s): Mus musculus
• Expression System: Homo sapiens


• 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) 

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.5 Å
• R-Value Free: 0.281 
• R-Value Work: 0.257 

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

• PubMed: 27374339 
• DOI: 10.1016/j.cub.2016.06.028


• 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 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.

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Related Citations: 

• 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
• 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
• 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




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Organizational Affiliation: 

Department of Biosciences and Nutrition & Center for Innovative Medicine, Karolinska Institutet, Huddinge, SE-141 83, Sweden.

Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
Izumo sperm-egg fusion protein 1	A	236	Mus musculus	Mutation(s): 0  Gene Names: Izumo1
Find proteins for Q9D9J7 (Mus musculus) Go to UniProtKB:  Q9D9J7

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram & Interactions
EPE	A	4-(2-HYDROXYETHYL)-1-PIPERAZINE ETHANESULFONIC ACID HEPES C8 H18 N2 O4 S JKMHFZQWWAIEOD-UHFFFAOYSA-N
NAG	A	N-ACETYL-D-GLUCOSAMINE C8 H15 N O6 OVRNDRQMDRJTHS-FMDGEEDCSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.5 Å
• R-Value Free: 0.281 
• R-Value Work: 0.257 
• Space Group: I 4 2 2

Unit Cell:

Length (Å)	Angle (°)
a = 103.280	α = 90.00
b = 103.280	β = 90.00
c = 139.270	γ = 90.00

Software Package:

Software Name	Purpose
XDS	data scaling
XDS	data reduction
PHENIX	refinement
PHASER	phasing

Structure Validation

Entry History & Funding Information

Deposition Data

• Deposited Date: 2016-05-11 
• Released Date: 2016-07-06 
• Deposition Author(s): Nishimura, K., Han, L., De Sanctis, D., Jovine, L.

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Funding Organization	Location	Grant Number
Karolinska Institutet	Sweden	--
Swedish Research Council	Sweden	2012-5093
Goran Gustafsson Foundation for Research in Natural Sciences and Medicine	Sweden	--
Sven and Ebba-Christina Hagberg foundation	Sweden	--
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
  Type: Database references