Regulation and crystallization of phosphorylated and dephosphorylated forms of truncated dimeric phenylalanine hydroxylase

• Published in: Protein science Vol. 6; no. 6; pp. 1352 - 1357
• Main Authors: Kobe, Bostjan, House, Colin M., Feil, Susanne C., Michell, Belinda J., Tiganis, Tony, Parker, Michael W., Kemp, Bruce E., Cotton, Richard G.H., Jennings, Ian G.
• Format: Journal Article
• Language: English
• Published: Bristol Cold Spring Harbor Laboratory Press 01-06-1997
• Subjects: Animals; Baculoviridae - genetics; crystallization; Crystallography, X-Ray; Dimerization; Enzyme Activation; Humans; Mass Spectrometry; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; phenylalanine hydroxylase; Phenylalanine Hydroxylase - chemistry; Phenylalanine Hydroxylase - genetics; Phenylalanine Hydroxylase - metabolism; Phenylketonurias - etiology; Phosphoproteins - chemistry; Phosphoproteins - genetics; Phosphoproteins - metabolism; Phosphorylation; Protein Conformation; protein phosphorylation; quaternary structure; Rats; Recombinant Proteins - chemistry; Sequence Deletion; Spodoptera - cytology; X‐ray crystallography
• ISSN: 0961-8368; 1469-896X
• DOI: 10.1002/pro.5560060626

Phenylalanine hydroxylase is regulated in a complex manner, including activation by phosphorylation. It is normally found as an equilibrium of dimeric and tetrameric species, with the tetramer thought to be the active form. We converted the protein to the dimeric form by deleting the C‐terminal 24 residues and show that the truncated protein remains active and regulated by phosphorylation. This indicates that changes in the tetrameric quaternary structure of phenylalanine hydroxylase are not required for enzyme activation. Truncation also facilitates crystallization of both phosphorylated and dephosphorylated forms of the enzyme.