Structural basis of autoregulation of phenylalanine hydroxylase

Nat Struct Biol. 1999 May;6(5):442-8. doi: 10.1038/8247.


Phenylalanine hydroxylase converts phenylalanine to tyrosine, a rate-limiting step in phenylalanine catabolism and protein and neurotransmitter biosynthesis. It is tightly regulated by the substrates phenylalanine and tetrahydrobiopterin and by phosphorylation. We present the crystal structures of dephosphorylated and phosphorylated forms of a dimeric enzyme with catalytic and regulatory properties of the wild-type protein. The structures reveal a catalytic domain flexibly linked to a regulatory domain. The latter consists of an N-terminal autoregulatory sequence (containing Ser 16, which is the site of phosphorylation) that extends over the active site pocket, and an alpha-beta sandwich core that is, unexpectedly, structurally related to both pterin dehydratase and the regulatory domains of metabolic enzymes. Phosphorylation has no major structural effects in the absence of phenylalanine, suggesting that phenylalanine and phosphorylation act in concert to activate the enzyme through a combination of intrasteric and possibly allosteric mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation / drug effects
  • Amino Acid Sequence
  • Animals
  • Binding Sites / genetics
  • Catalytic Domain / genetics
  • Crystallization
  • Crystallography, X-Ray
  • Dimerization
  • Evolution, Molecular
  • Humans
  • Mixed Function Oxygenases / chemistry
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Phenylalanine / metabolism
  • Phenylalanine / pharmacology
  • Phenylalanine Hydroxylase / chemistry*
  • Phenylalanine Hydroxylase / genetics
  • Phenylalanine Hydroxylase / metabolism*
  • Phenylketonurias / enzymology
  • Phenylketonurias / genetics
  • Phosphorylation
  • Protein Conformation
  • Rats
  • Sequence Homology, Amino Acid


  • Peptide Fragments
  • Phenylalanine
  • Mixed Function Oxygenases
  • Phenylalanine Hydroxylase

Associated data

  • PDB/1PHZ
  • PDB/2PHM