9OCW

A constitutively active construct of eukaryotic elongation factor 2 kinase

Summary for 9OCW

• Entry DOI: 10.2210/pdb9ocw/pdb
• Descriptor: Calmodulin-1,Eukaryotic elongation factor 2 kinase, ADENOSINE-5'-DIPHOSPHATE, ZINC ION, ... (6 entities in total)
• Functional Keywords: kinase, elongation, eef2k, eef-2k, eef2, biosynthetic protein, translation
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 1
• Total formula weight: 69958.80

Authors

Piserchio, A.,Long, K.,Isiorho, E.A.,Dalby, K.,Ghose, R. (deposition date: 2025-04-25, release date: 2026-03-04)

Primary citation

Long, K.J.,Browning, L.S.,Piserchio, A.,Isiorho, E.A.,Gadallah, M.I.,Douangvilay, J.,Wang, E.Y.,Kalugin, J.K.,Brodbelt, J.S.,Ghose, R.,Dalby, K.N.
The critical role of the C-terminal lobe of calmodulin in activating eukaryotic elongation factor 2 kinase.
J.Biol.Chem., 301:110650-110650, 2025

PubMed Abstract: Eukaryotic elongation factor 2 kinase (eEF-2K), a member of the α-kinase family, modulates translational rates by phosphorylating eEF-2, a GTPase that facilitates the translocation of the nascent chain on the ribosome during the elongation phase of protein synthesis. eEF-2K is regulated by diverse cellular cues, many of which sensitize it to the Ca-effector protein calmodulin (CaM). CaM, which binds and allosterically activates eEF-2K in the presence of Ca, contains two structural "lobes," each with a pair of Ca-binding EF hands. Using kinetic analysis, we demonstrate that the isolated C-terminal lobe of CaM (CaM) is sufficient to engage and fully activate eEF-2K in a Ca-dependent fashion. Genetically fusing CaM to the N terminus of eEF-2K, upstream of its critical CaM-targeting motif via a flexible 2-glycine linker, results in a chimeric species (CaM is linked to N-truncated eEF-2K [C-LiNK]) that is constitutively active independent of external CaM and Ca. A structure of the C-LiNK functional core reveals no substantial deviation in the overall conformations of the structural modules and orientations of key catalytic-site residues relative to the heterodimeric complex between full-length CaM and eEF-2K. These observations demonstrate that, in contrast to other CaM-regulated kinases, CaM alone is sufficient to activate eEF-2K fully. The proximity effect of CaM in the context of C-LiNK removes the requirement for external Ca, whose apparent role is to enhance the CaM affinity of eEF-2K and drive kinase activation. Further, the responsiveness of eEF-2K to regulatory stimuli in cells appears to be lost in C-LiNK, presumably due to its permanently "on" state.

PubMed: 40885389
DOI: 10.1016/j.jbc.2025.110650

Experimental method

X-RAY DIFFRACTION (2.27 Å)