Imaging single CaMKII holoenzymes at work by high-speed atomic force microscopy.

Tsujioka, Shotaro; Sumino, Ayumi; Nagasawa, Yutaro; Sumikama, Takashi; Flechsig, Holger; Puppulin, Leonardo; Tomita, Takuya; Baba, Yudai et al. · Sci Adv · 2023

basic_science · Level V

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Abstract

Ca<sup>2+</sup>/calmodulin-dependent protein kinase II (CaMKII) plays a pivotal role in synaptic plasticity. It is a dodecameric serine/threonine kinase that has been highly conserved across metazoans for over a million years. Despite the extensive knowledge of the mechanisms underlying CaMKII activation, its behavior at the molecular level has remained unobserved. In this study, we used high-speed atomic force microscopy to visualize the activity-dependent structural dynamics of rat/hydra/<i>C. elegans</i> CaMKII with nanometer resolution. Our imaging results revealed that the dynamic behavior is dependent on CaM binding and subsequent pT286 phosphorylation. Among the species studies, only rat CaMKIIα with pT286/pT305/pT306 exhibited kinase domain oligomerization. Furthermore, we revealed that the sensitivity of CaMKII to PP2A in the three species differs, with rat, <i>C. elegans</i>, and hydra being less dephosphorylated in that order. The evolutionarily acquired features of mammalian CaMKIIα-specific structural arrangement and phosphatase tolerance may differentiate neuronal function between mammals and other species.

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