Solution conformation of bovine lens alpha- and betaB2-crystallin terminal extensions.
alpha- and betaB2-Crystallin are the major proteins in the mammalian lens. Each of these crystallins has short, flexible terminal extensions from its domain core; the two alpha-crystallin subunits have C-terminal extensions of eight and ten amino acids whilst betaB2-crystallin has N- and C-terminal extensions of 15 and 11 amino acids, respectively. The solution conformations of these chemically synthesised extensions have been examined by two-dimensional 1H NMR spectroscopy. The N-terminal extension of betaB2-crystallin and the C-terminal extensions of alpha-crystallin adopt little ordered structure. In the membrane-mimicking solvent trifluoroethanol, the alpha-crystallin extensions are also unstructured. In contrast, the C-terminal extension of betaB2-crystallin in water has a structural preference towards turn-like structures, creating a hydrophobic region involving G198, F200 and P202. In the lens, the C-terminal extension of betaB2-crystallin is the only one of these extensions that interacts to any large extent with other crystallins. The structural preference of the C-terminal extension of betaB2-crystallin may therefore have implications for the role of this extension in crystallin-crystallin interactions.
Australian Cataract Research Foundation, Department of Chemistry, The University of Wollongong, New South Wales, Australia.
E R
ER
Le Breton
J A
JA
Carver
D000818:Animals; D002417:Cattle; D003459:Crystallins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D011522:Protons; D012996:Solutions
D003459:Crystallins; D010446:Peptide Fragments; D011522:Protons; D012996:Solutions