Abstract
X-ray crystallographic studies have previously shown that glutamate dehydrogenase from Clostridium symbiosum is a homohexamer. Mutation of the active-site aspartate-165 to histidine causes an alteration in the structural properties of the enzyme. The mutant enzyme, D165H exists predominantly as a single species of lower molecular mass than the wild-type enzyme as indicated by gel filtration and sedimentation velocity analysis. The latter technique gives an s20,w value for D165H of (6.07 ± 0.01)S which compares with (11.08 ± 0.01)S for the wild-type, indicative of alteration of the homohexameric quaternary structure of the native enzyme to a dimeric form, a result confirmed by sedimentation equilibrium experiments. Further support for this is provided by chemical modification by Ellman's reagent of cysteine-144 in the mutant, a residue which is buried at the dimer-dimer interface in the wild-type enzyme and is normally inaccessible to modification. The results suggest a possible structural route for communication between the active sites and subunit interfaces which may be important for relaying signals between subunits in allosteric regulation of the enzyme.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Accepted: 11 November 1996
Rights and permissions
About this article
Cite this article
Dean, J., Cölfen, H., Harding, S. et al. Alteration of the quaternary structure of glutamate dehydrogenase from Clostridium symbiosum by a single mutation distant from the subunit interfaces. Eur Biophys J 25, 417–422 (1997). https://doi.org/10.1007/s002490050055
Issue Date:
DOI: https://doi.org/10.1007/s002490050055