FCCC LOGO Faculty Publications
Jaffe EK , Stith L , Lawrence SH , Andrake M , Dunbrack RL Jr
A new model for allosteric regulation of phenylalanine hydroxylase: Implications for disease and therapeutics
Arch Biochem Biophys. 2013 Feb 15;530(2) :73-82
PMID: 23296088   
Back to previous list
The structural basis for allosteric regulation of phenylalanine hydroxylase (PAH), whose dysfunction causes phenylketonuria (PKU), is poorly understood. A new morpheein model for PAH allostery is proposed to consist of a dissociative equilibrium between two architecturally different tetramers whose interconversion requires a approximately 90 degrees rotation between the PAH catalytic and regulatory domains, the latter of which contains an ACT domain. This unprecedented model is supported by in vitro data on purified full length rat and human PAH. The conformational change is both predicted to and shown to render the tetramers chromatographically separable using ion exchange methods. One novel aspect of the activated tetramer model is an allosteric phenylalanine binding site at the intersubunit interface of ACT domains. Amino acid ligand-stabilized ACT domain dimerization follows the multimerization and ligand binding behavior of ACT domains present in other proteins in the PDB. Spectroscopic, chromatographic, and electrophoretic methods demonstrate a PAH equilibrium consisting of two architecturally distinct tetramers as well as dimers. We postulate that PKU-associated mutations may shift the PAH quaternary structure equilibrium in favor of the low activity assemblies. Pharmacological chaperones that stabilize the ACT:ACT interface can potentially provide PKU patients with a novel small molecule therapeutic.
Jaffe, Eileen K Stith, Linda Lawrence, Sarah H Andrake, Mark Dunbrack, Roland L Jr P30 CA006927/CA/NCI NIH HHS/United States R01 GM084453/GM/NIGMS NIH HHS/United States United States Archives of biochemistry and biophysics Nihms433184 Arch Biochem Biophys. 2013 Feb 15;530(2):73-82. doi: 10.1016/j.abb.2012.12.017. Epub 2013 Jan 11.