CaMKII binds both substrates and effectors at the active site

Ozden, C.; Sloutsky, R.; Santos, N.; Agnello, E.; Gaubitz, C.; Esposito, E. A.; Lapinskas, E.; Kelch, B. A.; Garman, S. C.; Hayashi, Y.; Stratton, M.

doi:10.1101/2020.10.25.354241

bioRxiv · 10.1101/2020.10.25.354241

CaMKII binds both substrates and effectors at the active site

Ozden, C.·Sloutsky, R.·Santos, N.·Agnello, E.·Gaubitz, C.·Esposito, E. A.·Lapinskas, E.·Kelch, B. A.·Garman, S. C.·Hayashi, Y.·Stratton, M.

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Abstract

Ca2+/calmodulin dependent protein kinase II (CaMKII) is a signaling protein required for long-term memory. Once activated by Ca2+/CaM, it sustains activity even after the Ca2+ dissipates. In addition to well-known autophosphorylation-mediated mechanism, interaction with specific binding partners also persistently activates CaMKII. A longstanding model invokes two distinct S- and T-sites. If an interactor binds at the T-site, it will preclude autoinhibition and allow substrates to be phosphorylated at the S-site. Here, we specifically test this model with X-ray crystallography, molecular dynamics simulations, and biochemistry. Our data are inconsistent with this model. Co-crystal structures of four different activators or substrates show that they all bind to a single continuous site across the kinase domain. We propose a mechanistic model that persistent CaMKII activity is facilitated by high affinity binding partners, which kinetically compete with autoinhibition by the regulatory segment to allow substrate phosphorylation.

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Ozden, C., Sloutsky, R., Santos, N., Agnello, E., Gaubitz, C., Esposito, E. A., Lapinskas, E., Kelch, B. A., Garman, S. C., Hayashi, Y., Stratton, M.. 2020-10-26. CaMKII binds both substrates and effectors at the active site. https://doi.org/10.1101/2020.10.25.354241

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