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Structure of the Pho85-Pho80 CDK-cyclin complex of the phosphate-responsive signal transduction pathway.

The ability to sense and respond appropriately to environmental changes is a primary requirement of all living organisms. In response to phosphate limitation, Saccharomyces cerevisiae induces transcription of a set of genes involved in the regulation of phosphate acquisition from the ambient environment. A signal transduction pathway (the PHO pathway) mediates this response, with Pho85-Pho80 playing a vital role. Here we report the X-ray structure of Pho85-Pho80, a prototypic structure of a CDK-cyclin complex functioning in transcriptional regulation in response to environmental changes. The structure revealed a specific salt link between a Pho85 arginine and a Pho80 aspartate that makes phosphorylation of the Pho85 activation loop dispensable and that maintains a Pho80 loop conformation for possible substrate recognition. It further showed two sites on the Pho80 cyclin for high-affinity binding of the transcription factor substrate (Pho4) and the CDK inhibitor (Pho81) that are markedly distant to each other and the active site.

Pubmed ID: 18042456


  • Huang K
  • Ferrin-O'Connell I
  • Zhang W
  • Leonard GA
  • O'Shea EK
  • Quiocho FA


Molecular cell

Publication Data

November 30, 2007

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM051377
  • Agency: NIGMS NIH HHS, Id: GM068826
  • Agency: NIGMS NIH HHS, Id: R01 GM051377
  • Agency: NIGMS NIH HHS, Id: R01 GM051377-14
  • Agency: NIGMS NIH HHS, Id: R01 GM068826
  • Agency: NIGMS NIH HHS, Id: R01 GM068826-04

Mesh Terms

  • Binding Sites
  • Crystallography, X-Ray
  • Cyclin-Dependent Kinases
  • Cyclins
  • DNA-Binding Proteins
  • Enzyme Activation
  • Enzyme Inhibitors
  • Models, Molecular
  • Mutant Proteins
  • Phenylalanine
  • Phosphates
  • Phosphorylation
  • Protein Binding
  • Protein Structure, Secondary
  • Repressor Proteins
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Signal Transduction
  • Structure-Activity Relationship
  • Substrate Specificity
  • Transcription Factors