Binding of TPX2 to Aurora A alters substrate and inhibitor interactions

Biochemistry. 2007 Sep 11;46(36):10287-95. doi: 10.1021/bi7011355. Epub 2007 Aug 18.

Abstract

The Aurora kinases are a family of serine/threonine kinases involved in mitosis. The expression of AurA is ubiquitous and cell cycle regulated. It is overexpressed in many tumor types, including breast, colon, and ovarian. TPX2 is a binding partner and activator of AurA. A fragment of TPX2 (residues 1-43) has been shown to be sufficient for binding, kinase activation, and protection from dephosphorylation. We have shown that the addition of TPX2(1-43) increases the catalytic efficiency of AurA. While TPX2 binding has no effect on the turnover number of AurA and does not change the reaction mechanism (characterized here to be a rapid equilibrium random mechanism), it increases the binding affinity of both ATP and a peptide substrate. We have also demonstrated differences in the inhibitor structure-activity relationship (SAR) in the presence or absence of TPX2(1-43). To better understand the differential SAR, we carried out computer modeling studies to gain insight into the effect of TPX2 on the binding interactions between AurA and inhibitors. Our working hypothesis is that TPX2 binding decreases the size and accessibility of a hydrophobic pocket, adjacent to the ATP site, to inhibitors.

MeSH terms

  • Adenosine Diphosphate / pharmacology
  • Alanine
  • Amino Acid Sequence
  • Aurora Kinases
  • Catalysis / drug effects
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / metabolism*
  • Cell Cycle Proteins / pharmacology*
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Kinetics
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / metabolism*
  • Microtubule-Associated Proteins / pharmacology*
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / metabolism*
  • Nuclear Proteins / pharmacology*
  • Phosphopeptides / chemistry
  • Protein Binding / drug effects
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors*
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / metabolism*
  • Staurosporine / pharmacology
  • Structure-Activity Relationship
  • Substrate Specificity / drug effects
  • Titrimetry

Substances

  • Cell Cycle Proteins
  • Enzyme Inhibitors
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • Phosphopeptides
  • TPX2 protein, human
  • Adenosine Diphosphate
  • Aurora Kinases
  • Protein-Serine-Threonine Kinases
  • Staurosporine
  • Alanine