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Nat Chem Biol. 2019 Feb 4. doi: 10.1038/s41589-018-0215-0. [Epub ahead of print]

A class of highly selective inhibitors bind to an active state of PI3Kγ.

Author information

1
Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden.
2
Department of Biomedicine, University of Basel, Basel, Switzerland.
3
Respiratory, Inflammation & Autoimmunity, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden.
4
Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden.
5
MRC Laboratory of Molecular Biology, Cambridge, UK.
6
Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden. jens.petersen@astrazeneca.com.

Abstract

We have discovered a class of PI3Kγ inhibitors exhibiting over 1,000-fold selectivity over PI3Kα and PI3Kβ. On the basis of X-ray crystallography, hydrogen-deuterium exchange-mass spectrometry and surface plasmon resonance experiments we propose that the cyclopropylethyl moiety displaces the DFG motif of the enzyme away from the adenosine tri-phosphate binding site, inducing a large conformational change in both the kinase- and helical domains of PI3Kγ. Site directed mutagenesis explained how the conformational changes occur. Our results suggest that these cyclopropylethyl substituted compounds selectively inhibit the active state of PI3Kγ, which is unique to these compounds and to the PI3Kγ isoform, explaining their excellent potency and unmatched isoform selectivity that were confirmed in cellular systems. This is the first example of a Class I PI3K inhibitor achieving its selectivity by affecting the DFG motif in a manner that bears similarity to DFG in/out for type II protein kinase inhibitors.

PMID:
30718815
DOI:
10.1038/s41589-018-0215-0

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