Definition of the binding mode of a new class of phosphoinositide 3-kinase α-selective inhibitors using in vitro mutagenesis of non-conserved amino acids and kinetic analysis

Biochem J. 2012 Jun 15;444(3):529-35. doi: 10.1042/BJ20120499.

Abstract

The binding mechanism of a new class of lipid-competitive, ATP non-competitive, p110α isoform-selective PI3K (phosphoinositide 3-kinase) inhibitors has been elucidated. Using the novel technique of isoform reciprocal mutagenesis of non-conserved amino acids in the p110α and p110β isoforms, we have identified three unique binding mechanisms for the p110α-selective inhibitors PIK-75, A-66S and J-32. Each of the inhibitor's p110α-isoform-selective binding was found to be due to interactions with different amino acids within p110. The PIK-75 interaction bound the non-conserved region 2 amino acid p110α Ser(773), A-66S bound the region 1 non-conserved amino acid p110α Gln(859), and J-32 binding had an indirect interaction with Lys(776) and Ile(771). The isoform reciprocal mutagenesis technique is shown to be an important analytical tool for the rational design of isoform-selective inhibitors.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / genetics
  • Amino Acids / metabolism*
  • Class I Phosphatidylinositol 3-Kinases
  • Class II Phosphatidylinositol 3-Kinases / genetics
  • Class II Phosphatidylinositol 3-Kinases / metabolism
  • Conserved Sequence / genetics
  • Dose-Response Relationship, Drug
  • Hydrazones / metabolism
  • Hydrazones / pharmacology
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Kinetics
  • Mutagenesis, Site-Directed*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors*
  • Proline / analogs & derivatives*
  • Proline / genetics
  • Proline / metabolism
  • Protein Binding / genetics
  • Sulfonamides / metabolism
  • Sulfonamides / pharmacology
  • Thiazoles / metabolism*

Substances

  • Amino Acids
  • Hydrazones
  • Isoenzymes
  • N1-(2-(t-butyl)-4'-methyl-(4,5'-bithiazol)- 2'-yl)pyrrolidine-1,2-dicarboxamide
  • PIK 75
  • Phosphoinositide-3 Kinase Inhibitors
  • Sulfonamides
  • Thiazoles
  • Proline
  • Class I Phosphatidylinositol 3-Kinases
  • Class II Phosphatidylinositol 3-Kinases
  • p110delta protein, rat