Phosphorylation of the N-terminal domain regulates subcellular localization and DNA binding properties of the peptidyl-prolyl cis/trans isomerase hPar14

J Mol Biol. 2003 Jul 25;330(5):955-66. doi: 10.1016/s0022-2836(03)00713-7.


Human parvulin 14 (hPar14) is a folding helper enzyme belonging to the parvulin family of peptidyl-prolyl cis/trans isomerases (PPIases). This enzyme is thought to play a role in cell-cycle and chromatin remodeling. Although hPar14 was nuclearly localized and bound to double-stranded DNA, the molecular basis of the subcellular localization and the functional regulation remained unknown. Here we show that subcellular localization and DNA-binding ability of hPar14 is regulated by posttranslational modification of its N-terminal domain. As proved by MALDI-TOF mass spectrometry and MS/MS fragmentation, hPar14 is phosphorylated at Ser19 in vitro and in vivo. In human HeLa cells the protein is most likely modified by casein kinase 2 (CK2). Phosphorylation of hPar14 is inhibited both in vitro and in vivo by 5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole (DRB), a specific inhibitor of CK2 activity. Mutation of Ser19 to Ala abolishes phosphorylation and alters the subcellular localization of hPar14 from predominantly nuclear to significantly cytoplasmic. Immunostaining shows that a Glu19 mutant of hPar14, which mimics the phosphorylated state of Ser19, is localized around the nuclear envelope, but does not penetrate into the nucleoplasm. In contrast to wild-type hPar14, the in vitro DNA-binding affinity of the Glu19 mutant is strongly reduced, suggesting that only the dephosphorylated protein is the active DNA-binding form of hPar14 in the nucleus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cell Cycle
  • Cell Nucleus / metabolism
  • Chromatin / metabolism
  • DNA / chemistry
  • DNA / metabolism*
  • Dichlororibofuranosylbenzimidazole / pharmacology
  • Dose-Response Relationship, Drug
  • Glutamic Acid / chemistry
  • HeLa Cells
  • Heparin / chemistry
  • Humans
  • Kinetics
  • Mass Spectrometry
  • Microscopy, Fluorescence
  • Mutation
  • NIMA-Interacting Peptidylprolyl Isomerase
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Peptidylprolyl Isomerase / chemistry*
  • Peptidylprolyl Isomerase / metabolism*
  • Phosphorylation
  • Plasmids / metabolism
  • Protein Binding
  • Protein Processing, Post-Translational
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Serine / chemistry
  • Sodium Chloride / pharmacology
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Subcellular Fractions
  • Time Factors
  • Transfection


  • Chromatin
  • NIMA-Interacting Peptidylprolyl Isomerase
  • Nucleic Acid Synthesis Inhibitors
  • Recombinant Proteins
  • Glutamic Acid
  • Sodium Chloride
  • Serine
  • Dichlororibofuranosylbenzimidazole
  • Heparin
  • DNA
  • PIN1 protein, human
  • PIN4 protein, human
  • Peptidylprolyl Isomerase