Flexible linkers in CaMKII control the balance between activating and inhibitory autophosphorylation

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Abstract

The many variants of human Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) differ in the lengths and sequences of disordered linkers connecting the kinase domains to the oligomeric hub of the holoenzyme. CaMKII activity depends on the balance between activating and inhibitory autophosphorylation (on Thr 286 and Thr 305/306, respectively, in the human a isoform). Variation in the linkers could alter transphosphorylation rates within a holoenzyme and the balance of autophosphorylation outcomes. We show, using mammalian-cell expression and a single-molecule assay, that the balance of autophosphorylation is flipped between CaMKII variants with longer and shorter linkers. For the principal isoforms in the brain, CaMKII-a, with a ~30 residue linker, readily acquires activating autophosphorylation, while CaMKII-b, with a ~200 residue linker, is biased towards inhibitory autophosphorylation. Our results show how the responsiveness of CaMKII holoenzymes to calcium signals can be tuned by varying the relative levels of isoforms with long and short linkers.

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All data generated or analyzed during this study are summarized in the manuscript, figures, appendix, and supplementary files. The in-house Matlab programs that are used for data analysis are provided as Source code file 1 and is open-access.

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Moitrayee Bhattacharyya

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0002-2168-1541
Young Kwang Lee

Department of Molecular and Cell Biology, San Diego State University, San Diego, United States

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0003-0056-6357
Serena Muratcioglu

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

Competing interests
No competing interests declared.
Baiyu Qiu

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

Competing interests
No competing interests declared.
Priya Nyayapati

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

Competing interests
No competing interests declared.
Howard Schulman

Panorama Institute of Molecular Medicine, Sunnyvale, United States

Competing interests
No competing interests declared.
Jay T Groves

QB3, University of California, Berkeley, Berkeley, United States

For correspondence
JTGroves@lbl.gov

Competing interests
No competing interests declared.
John Kuriyan

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

For correspondence
jkuriyan@mac.com

Competing interests
John Kuriyan, Senior editor, eLife.

"This ORCID iD identifies the author of this article:" 0000-0002-4414-5477

Funding

National Institute of General Medical Sciences (K99 GM 126145)

Moitrayee Bhattacharyya

Howard Hughes Medical Institute

John Kuriyan

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.