Crystallization and analysis of the subunit assembly and quaternary structure of imidazoleglycerol phosphate dehydratase from Saccharomyces cerevisiae.
Imidazoleglycerol phosphate dehydratase (IGPD) from Saccharomyces cerevisiae has been crystallized in the presence of a range of divalent cations using the hanging-drop method of vapour diffusion with ammonium sulfate or polyethylene glycol (PEG) 4000 as the precipitants. X-ray precession photographs have established that the crystals formed with ammonium sulfate (form A) belong to the space group F432, with cell parameter a = 177.5 A and a single subunit in the asymmetric unit. A preliminary data set collected to 6 A resolution on a two-detector San Diego Multiwire area detector has established that the crystals formed with PEG 4000 (form B) belong to either of the special pair of space groups I23 or I2(1)3, with cell parameter a = 131.0 A. A self-rotation function has been calculated using these data and indicates that the cell axes show pseudo fourfold symmetry consistent with a dimer in the asymmetric unit in this crystal form. Light-scattering studies indicate that in the presence of Mn(2+) and a number of other divalent cations IGPD undergoes assembly to a particle of molecular weight approximately 500 kDa. Given the subunit molecular weight of 23 kDa together with the symmetry of the crystals it would indicate that the most likely quaternary structure for this enzyme is based on a 24-mer in 432 symmetry.
Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, England.
K W
KW
Wilkinson
P J
PJ
Baker
D W
DW
Rice
H F
HF
Rodgers
T J
TJ
Stillman
T
T
Hawkes
P
P
Thomas
L
L
Edwards