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

Zhaohua Zheng, Syazwani Itri Amran, Jiuxiang Zhu, Oleg Schmidt-Kittler, Ken Kinzler, Bert Vogelstein, Peter R Shepherd, Philip Thompson, Ian Jennings

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Abstract

The binding mechanism of a new class of lipid-competitive, ATP non-competitive, p110 alpha 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 p110 alpha and p110 beta isoforms, we have identified three unique binding mechanisms for the p110 alpha-selective inhibitors PIK-75, A-66S and J-32. Each of the inhibitor s p110 alpha-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 p110 alpha Ser(773), A-66S bound the region 1 non-conserved amino acid p110 alpha 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.
Original languageEnglish
Pages (from-to)529 - 535
Number of pages7
JournalBiochemical Journal
Volume444
DOIs
Publication statusPublished - 2012

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