The molecular basis for phosphodependent substrate targeting and regulation of Plks by the Polo-box domain

Cell. 2003 Oct 3;115(1):83-95. doi: 10.1016/s0092-8674(03)00725-6.

Abstract

Polo-like kinases (Plks) perform crucial functions in cell-cycle progression and multiple stages of mitosis. Plks are characterized by a C-terminal noncatalytic region containing two tandem Polo boxes, termed the Polo-box domain (PBD), which has recently been implicated in phosphodependent substrate targeting. We show that the PBDs of human, Xenopus, and yeast Plks all recognize similar phosphoserine/threonine-containing motifs. The 1.9 A X-ray structure of a human Plk1 PBD-phosphopeptide complex shows that the Polo boxes each comprise beta6alpha structures that associate to form a 12-stranded beta sandwich domain. The phosphopeptide binds along a conserved, positively charged cleft located at the edge of the Polo-box interface. Mutations that specifically disrupt phosphodependent interactions abolish cell-cycle-dependent localization and provide compelling phenotypic evidence that PBD-phospholigand binding is necessary for proper mitotic progression. In addition, phosphopeptide binding to the PBD stimulates kinase activity in full-length Plk1, suggesting a conformational switching mechanism for Plk regulation and a dual functionality for the PBD.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Cell Cycle Proteins
  • Crystallography, X-Ray
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • HeLa Cells
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Molecular Structure
  • Mutation
  • Phosphopeptides / chemistry
  • Phosphopeptides / metabolism*
  • Protein Binding
  • Protein Conformation
  • Protein Kinases / chemistry
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins
  • Sequence Alignment
  • Substrate Specificity
  • Xenopus

Substances

  • Cell Cycle Proteins
  • Fungal Proteins
  • Phosphopeptides
  • Proto-Oncogene Proteins
  • Protein Kinases
  • PLK4 protein, human
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1

Associated data

  • PDB/1UMW