1BLB

CLOSE PACKING OF AN OLIGOMERIC EYE LENS BETA-CRYSTALLIN INDUCES LOSS OF SYMMETRY AND ORDERING OF SEQUENCE EXTENSIONS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.3 Å

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This is version 1.2 of the entry. See complete history

Literature

Close packing of an oligomeric eye lens beta-crystallin induces loss of symmetry and ordering of sequence extensions.

Nalini, V.Bax, B.Driessen, H.Moss, D.S.Lindley, P.F.Slingsby, C.

(1994) J.Mol.Biol. 236: 1250-1258


  • PubMed Abstract: 
  • beta-Crystallins are oligomeric eye lens proteins that are related to monomeric gamma-crystallins. The main sequence difference between the two families is the presence of sequence extensions in the beta-crystallins. A major question concerns the rol ...

    beta-Crystallins are oligomeric eye lens proteins that are related to monomeric gamma-crystallins. The main sequence difference between the two families is the presence of sequence extensions in the beta-crystallins. A major question concerns the role that these extensions play in mediating interactions at the high protein concentrations found in the lens. The predominant beta-crystallin polypeptide, beta B2, can be crystallized in two different space groups, I222 and C222. The I222 crystal structure revealed that the protein packed as a tetramer with perfect 222 symmetry but that the extensions were disordered. The X-ray structure of the C222 lattice of beta B2 has now been refined at 3.3 A, the structure analysed and compared with the I222 lattice. The protein is also a tetramer with 222 symmetry in the C222 lattice but differs in that parts of the N-terminal extensions have been visualized. In the asymmetric unit of the C222 lattice there are four subunits, each comprising a single polypeptide chain, in which certain flexible loops in the N-terminal domains and the N-terminal extensions have various conformations. The tetramers in the C222 lattice are more tightly packed than in the I222 form. Analysis of the tetramer contacts shows that the sites of interaction break the 222 symmetry of the tetramers. The N-terminal extensions play a major role in directing interactions between tetramers. One of the N-terminal extensions interacts with a hydrophobic patch on the N-terminal domain of another tetramer. These crystallographic observations obtained over a physiological concentration range indicate how, in beta-crystallin oligomers, the N-terminal extensions of beta B2 can switch from interacting with water to interacting with protein depending on their relative concentrations. This could be useful in maintaining a gradient of refractive index.


    Related Citations: 
    • Preliminary X-Ray Crystallographic Study of the Principle Subunit of the Lens Structural Protein, Bovine Beta-Crystallin
      Slingsby, C.,Miller, L.R.,Berbers, G.A.M.
      (1982) J.Mol.Biol. 157: 191
    • Structure of Oligomeric Betab2-Crystallin: An Application of the T2 Translation Function to an Asymmetric Unit Containing Two Dimers
      Driessen, H.P.C.,Bax, B.,Slingsby, C.,Lindley, P.F.,Mahadevan, D.,Moss, D.S.,Tickle, I.
      (1991) Acta Crystallogr.,Sect.B 47: 987


    Organizational Affiliation

    Laboratory of Molecular Biology, Birkbeck College, London University, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
BETA B2-CRYSTALLIN
A, B, C, D
204Bos taurusGene Names: CRYBB2
Find proteins for P02522 (Bos taurus)
Go to Gene View: CRYBB2
Go to UniProtKB:  P02522
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.3 Å
  • Space Group: C 2 2 2
Unit Cell:
Length (Å)Angle (°)
a = 154.710α = 90.00
b = 165.900β = 90.00
c = 78.480γ = 90.00
Software Package:
Software NamePurpose
X-PLORphasing
RESTRAINrefinement
X-PLORrefinement
X-PLORmodel building

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1994-12-20
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance