Crystal structure of an ice-binding protein from the perennial ryegrass, Lolium perenne

Experimental Data Snapshot

  • Resolution: 1.40 Å
  • R-Value Free: 0.187 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.166 

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Antifreeze protein from freeze-tolerant grass has a beta-roll fold with an irregularly structured ice-binding site.

Middleton, A.J.Marshall, C.B.Faucher, F.Bar-Dolev, M.Braslavsky, I.Campbell, R.L.Walker, V.K.Davies, P.L.

(2012) J Mol Biol 416: 713-724

  • DOI: https://doi.org/10.1016/j.jmb.2012.01.032
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The grass Lolium perenne produces an ice-binding protein (LpIBP) that helps this perennial tolerate freezing by inhibiting the recrystallization of ice. Ice-binding proteins (IBPs) are also produced by freeze-avoiding organisms to halt the growth of ice and are better known as antifreeze proteins (AFPs). To examine the structural basis for the different roles of these two IBP types, we have solved the first crystal structure of a plant IBP. The 118-residue LpIBP folds as a novel left-handed beta-roll with eight 14- or 15-residue coils and is stabilized by a small hydrophobic core and two internal Asn ladders. The ice-binding site (IBS) is formed by a flat beta-sheet on one surface of the beta-roll. We show that LpIBP binds to both the basal and primary-prism planes of ice, which is the hallmark of hyperactive AFPs. However, the antifreeze activity of LpIBP is less than 10% of that measured for those hyperactive AFPs with convergently evolved beta-solenoid structures. Whereas these hyperactive AFPs have two rows of aligned Thr residues on their IBS, the equivalent arrays in LpIBP are populated by a mixture of Thr, Ser and Val with several side-chain conformations. Substitution of Ser or Val for Thr on the IBS of a hyperactive AFP reduced its antifreeze activity. LpIBP may have evolved an IBS that has low antifreeze activity to avoid damage from rapid ice growth that occurs when temperatures exceed the capacity of AFPs to block ice growth while retaining the ability to inhibit ice recrystallization.

  • Organizational Affiliation

    Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ice recrystallization inhibition protein-like protein
A, B
133Lolium perenneMutation(s): 0 
Gene Names: IRI3
Find proteins for B5T007 (Lolium perenne)
Explore B5T007 
Go to UniProtKB:  B5T007
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupB5T007
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on EDO

Download Ideal Coordinates CCD File 
C [auth A],
J [auth B]
C2 H6 O2
Query on EOH

Download Ideal Coordinates CCD File 
D [auth A]
E [auth A]
F [auth A]
G [auth A]
H [auth A]
D [auth A],
E [auth A],
F [auth A],
G [auth A],
H [auth A],
I [auth A],
K [auth B],
L [auth B],
M [auth B],
N [auth B],
O [auth B]
C2 H6 O
Experimental Data & Validation

Experimental Data

  • Resolution: 1.40 Å
  • R-Value Free: 0.187 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.166 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 94.28α = 90
b = 62.49β = 113.96
c = 44γ = 90
Software Package:
Software NamePurpose
XSCALEdata scaling
PDB_EXTRACTdata extraction
Blu-Icedata collection
XDSdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-02-15
    Type: Initial release
  • Version 1.1: 2012-04-18
    Changes: Database references
  • Version 1.2: 2024-02-28
    Changes: Data collection, Database references, Derived calculations