Mutagenesis of the crystal contact of acidic fibroblast growth factor.
An attempt has been made to improve a crystal contact of human acidic fibroblast growth factor (haFGF; 140 amino acids) to control the crystal growth, because haFGF crystallizes only as a thin-plate form, yielding crystals suitable for X-ray but not neutron diffraction. X-ray crystal analysis of haFGF showed that the Glu81 side chain, located at a crystal contact between haFGF molecules, is in close proximity with an identical residue related by crystallographic symmetry, suggesting that charge repulsion may disrupt suitable crystal-packing interactions. To investigate whether the Glu residue affects the crystal-packing interactions, haFGF mutants in which Glu81 was replaced by Ala, Val, Leu, Ser and Thr were constructed. Although crystals of the Ala and Leu mutants were grown as a thin-plate form by the same precipitant (formate) as the wild type, crystals of the Ser and Thr mutants were grown with increased thickness, yielding a larger overall crystal volume. X-ray structural analysis of the Ser mutant determined at 1.35 A resolution revealed that the hydroxy groups of Ser are linked by hydrogen bonds mediated by the formate used as a precipitant. This approach to engineering crystal contacts may contribute to the development of large protein crystals for neutron crystallography.
Honjo
Eijiro
E
Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195, Japan. honjo.ejiiro@jaea.go.jp
Tamada
Taro
T
Adachi
Motoyasu
M
Kuroki
Ryota
R
Meher
Akshaya
A
Blaber
Michael
M
D018360:Crystallography, X-Ray; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D016296:Mutagenesis; D011487:Protein Conformation
D016220:Fibroblast Growth Factor 1