Disease related mutations in PI3Kγ disrupt regulatory C-terminal dynamics and reveal a path to selective inhibitors

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Abstract

Class I Phosphoinositide 3-kinases (PI3Ks) are master regulators of cellular functions, with the class IB PI3K catalytic subunit (p110g) playing key roles in immune signalling. p110g is a key factor in inflammatory diseases, and has been identified as a therapeutic target for cancers due to its immunomodulatory role. Using a combined biochemical/biophysical approach, we have revealed insight into regulation of kinase activity, specifically defining how immunodeficiency and oncogenic mutations of R1021 in the C-terminus can inactivate or activate enzyme activity. Screening of inhibitors using HDX-MS revealed that activation loop-binding inhibitors induce allosteric conformational changes that mimic those in the R1021C mutant. Structural analysis of advanced PI3K inhibitors in clinical development revealed novel binding pockets that can be exploited for further therapeutic development. Overall this work provides unique insights into regulatory mechanisms that control PI3Kg kinase activity, and shows a framework for the design of PI3K isoform and mutant selective inhibitors.

Data availability

The crystallography data has been deposited in the protein data bank with accession numbers (PDB: 7JWE, 7JX0, 7JWZ). The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository[83] with the dataset identifier PXD021132. All data generated or analyzed during this study are included in the manuscript and supporting files. Specifically biochemical kinase assay data are included in the source data files.

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Article and author information

Author details

Manoj K Rathinaswamy

Biochemistry and Microbiology, University of Victoria, Victoria, Canada

Competing interests
The authors declare that no competing interests exist.
Zied Gaieb

Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, United States

Competing interests
The authors declare that no competing interests exist.
Kaelin D Fleming

Biochemistry and Microbiology, University of Victoria, Victoria, Canada

Competing interests
The authors declare that no competing interests exist.
Chiara Borsari

Department of Biomedicine, University of Basel, Basel, Switzerland

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-4688-8362
Noah J Harris

Biochemistry and Microbiology, University of Victoria, Victoria, Canada

Competing interests
The authors declare that no competing interests exist.
Brandon J Moeller

Biochemistry and Microbiology, University of Victoria, Victoria, Canada

Competing interests
The authors declare that no competing interests exist.
Matthias P Wymann

Department of Biomedicine, University of Basel, Basel, Switzerland

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-3349-4281
Rommie E Amaro

Chemistry and Biochemistry, National Biomedical Computation Resource, University of California, San Diego, La Jolla, United States

Competing interests
The authors declare that no competing interests exist.
John E Burke

Biochemistry and Microbiology, University of Victoria, Victoria, Canada

For correspondence
jeburke@uvic.ca

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-7904-9859

Funding

Cancer Research Society (CRS-24368)

John E Burke

Michael Smith Foundation for Health Research (17686)

John E Burke

Canadian Institutes of Health Research (New Investigator)

John E Burke

National Institutes of Health (GM132826)

Zied Gaieb
Rommie E Amaro

Stiftung FHNW (341)

Matthias P Wymann

Swiss National Science (310030_189065)

Matthias P Wymann

Novartis Foundation (14B095)

Matthias P Wymann

Innosuisse - Schweizerische Agentur für Innovationsförderung (37213.1 IP-LS)

Matthias P Wymann

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.