title: 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.
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.
authors.affiliation: Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria 3052, Australia.
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Zheng
authors.forename: Syazwani I
authors.initials: SI
authors.lastname: Amran
authors.forename: Jiuxiang
authors.initials: J
authors.lastname: Zhu
authors.forename: Oleg
authors.initials: O
authors.lastname: Schmidt-Kittler
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Kinzler
authors.forename: Bert
authors.initials: B
authors.lastname: Vogelstein
authors.forename: Peter R
authors.initials: PR
authors.lastname: Shepherd
authors.forename: Philip E
authors.initials: PE
authors.lastname: Thompson
authors.forename: Ian G
authors.initials: IG
authors.lastname: Jennings
mesh_terms: D000596:Amino Acids / Q000235:genetics / Q000378:metabolism*; D058534:Class I Phosphatidylinositol 3-Kinases; D058541:Class II Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D006835:Hydrazones / Q000378:metabolism / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011392:Proline / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D013449:Sulfonamides / Q000378:metabolism / Q000494:pharmacology; D013844:Thiazoles / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D058534:Class I Phosphatidylinositol 3-Kinases; D058541:Class II Phosphatidylinositol 3-Kinases; D006835:Hydrazones; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011392:Proline; D013449:Sulfonamides; D013844:Thiazoles; C000592780:N1-(2-(t-butyl)-4'-methyl-(4,5'-bithiazol)- 2'-yl)pyrrolidine-1,2-dicarboxamide; C549211:PIK 75; C488371:p110delta protein, rat